TY - CONF A1 - Wosniok, Aleksander T1 - Optical fibers for sensing applications: Towards ionizing radiation monitoring N2 - Overview about existing fiber optic sensing techniques including ionizing radiation monitoring. T2 - WP7 Meeting EU project PREDIS CY - Online meeting DA - 05.02.2021 KW - Fiber optic sensor KW - Radiation-induced attenuation KW - Radiation sensing fibers KW - Distributed sensing PY - 2021 AN - OPUS4-52090 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wosniok, Aleksander A1 - Krebber, Katerina T1 - Distributed fiber optic radiation sensors N2 - In this work, we present our results achieved in several research activities for development of distributed fiber optic radiation sensors using glass and polymer optical fibers. The findings show that both the measurement of the radiation-induced attenuation (RIA) along the entire sensing fiber and the accompanying change in the refractive index of the fiber core can be used for distributed radiation monitoring. T2 - safeND CY - Online meeting DA - 10.11.2021 KW - Distributed fiber optic radiation sensors KW - Radiation-induced attenuation KW - Optical fiber sensor KW - Incoherent optical frequency domain reflectometry PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-537531 DO - https://doi.org/10.5194/sand-1-15-2021 VL - 1 SP - 15 EP - 16 AN - OPUS4-53753 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wosniok, Aleksander T1 - Fibre optic sensors for monitoring tasks in a radiation environment N2 - The topic of the presentation are distributed fiber optic measurement techniques that can be used for long-term monitoring of strain, temperature and radiation distribution in the radiation environment. The fiber optic sensors applied to the surface of waste packages provide detection and localization of cracks. T2 - Workshop WP7.3 EU project PREDIS CY - Online meeting DA - 15.11.2021 KW - Distributed sensing KW - Fiber optic sensor KW - Radiation sensing fibers KW - Brillouin distributed fiber sensor KW - Distributed acoustic sensing PY - 2021 AN - OPUS4-53751 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wosniok, Aleksander T1 - Distributed fiber optic radiation sensors N2 - In this work, we present our results achieved in several research activities for development of fiber optic dosimeters. The findings show that both the measurement of the radiation-induced attenuation (RIA) along the entire sensing fiber and the accom panying change in the refractive index of the fiber core can be used for distributed radiation monitoring in the kGy and MGy range, respectively. Depending on the fiber type and material the RIA shows varying response to dose rates, environmental temperatures and the wavelength of the laser source used. T2 - safeND CY - Online meeting DA - 10.11.2021 KW - Distributed sensing KW - Fiber optic radiation sensor KW - Radiation sensing fibers KW - Radiation-induced attenuation PY - 2021 AN - OPUS4-53752 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Prabhakara, Prathik T1 - Simulation and construction of a focussing borehole probe for ultrasonic investigations at sealing structures for radioactive waste repositories N2 - A novel ultrasonic borehole probe is developed for the quality assurance of sealing structures in radioactive waste repositories using existing research boreholes. The aim is to analyse the sealing structures made of salt concrete concerning potential cracks, delamination, and embedded objects. A first prototype of the probe uses 12 individual dry point contact (DPC) shear horizontal wave transducers separated by equidistant transmitter/receiver arrays, each consisting of six individual transducers. It is operated with a commercial handheld ultrasonic testing device used in civil engineering. In order to increase the generated sound pressure of the borehole probe, the number of transducers will be increased to 32 for the novel probe. In addition, a time-controlled excitation of the individual probes is used to steer a focused sound beam to a certain angle and focus on a certain distance based on calculated time delays. Hence, the sensitive test volume is more limited, and the signal-to-noise ratio of the received signals improved. This paper presents the validation of the newly developed phased array borehole probe by beam simulation and experimentally on a half-cylindrical test specimen to investigate the directional characteristics. In combination with geophysical reconstruction method, an optimised radiation characteristic of the probe, an improved signal quality and thus an increased reliability of the results in imaging is expected. This is of great importance to construct safe sealing structures needed for radioactive or toxic waste disposal. T2 - NDT UT-Online 21 CY - Online meeting DA - 01.11.2021 KW - Borehole probe KW - Engineered Barrier System (EBS) KW - SealWasteSafe KW - Phased array technique KW - Monitoring PY - 2021 AN - OPUS4-54500 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hicke, Konstantin T1 - Monitoring von Strukturverhalten mittels integrierter verteilter faseroptischer Sensorik - Verteilte akustische Sensorik (DAS) N2 - Die verteilte faseroptische akustische Sensorik (DAS) wird vorgestellt, hinsichtlich ihrer Leistungsfähigkeit beschrieben und verschiedenste Anwendungsfelder, z.B. für das Zustandsmonitoring oder für seismische Messungen, beispielhaft gezeigt. Zudem werden mögliche Anwendungsfelder von DAS für den Kontext Kerntechnische Entsorgung (KTE) und Rückbau aufgezeigt. T2 - Online-Workshop „Dauerhafte Verschlussbauwerke für Endlager“ CY - Online meeting DA - 14.02.2022 KW - Verteilte faseroptische Sensorik KW - Verteilte akustische Sensorik KW - DAS KW - KTE KW - Monitoring Endlager PY - 2022 AN - OPUS4-54348 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Baensch, Franziska T1 - Charakterisierung von Salzbeton und alkali-aktivierten Material basierend auf der Schallemissionsanalyse N2 - Nach einer kurzen Einführung in die Schallemissionsprüfung und -Analyse wird ein Versuchsstand vorgestellt, der im Rahmen des Themenfeldprojektes Seal Waste Safe installiert wurde. Schwerpunkt des Vortrages sind die Schallemissionsmessungen an einem 150 l Demonstrator aus Salzbeton und einem weiteren aus alkali-aktiviertem Material. Neben der konventionellen Schallemissionsanaylse mit Aktivitäts- und Intensitätsparametern der Zeitsignale, werden auch frequenzbasierte Parameter zur Analyse andiskutiert. N2 - After a brief introduction to acoustic emission testing and analysis, an experimental test setup is presented, which was part of the Seal Waste Safe project (internal BAM project 2019-2022). Herein, the acoustic emission measurements of a 150 l demonstrator made of salt concrete and another one made of alkali-activated material are focused. In addition to the conventional acoustic emission analysis regarding the activity and intensity parameters of the detected time signals, also frequency-based parameters were discussed for analysis. T2 - Dauerhafte Verschlussbauwerke für Endlager CY - Online meeting DA - 14.2.2022 KW - Acoustic Emission KW - Schallemission KW - Salzbeton KW - Alkali aktiviertes Material KW - Geopolymer PY - 2022 AN - OPUS4-54937 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stamm, Michael A1 - Krankenhagen, Rainer T1 - Weather-dependent passive thermography of unheated wind turbine blades N2 - Up to now, the inspection of wind turbines with industrial climbers has been considered ”state of the art”. However, ever-larger wind turbines and advancing digitization make modern and automated inspection methods indispensable. Passive thermography can serve as such a digital and atomized method while it is well known for its applications in the inspection of buildings or electrical circuits. However, its application relies on thermal gradients in the inspected object such that a temperature contrast exists between damaged and sound areas. This also holds for unheated structures like rotor blades of wind turbines which show no intrinsic temperature gradient and can hardly be heated. Under certain weather conditions with sufficient solar loading and diurnal temperature variations, passive thermography is suitable for the in-service inspection of rotor blades. However, for a reliable use of passive thermography on ”thermal passive” components, the incorporation of these environmental conditions in the planning and evaluation of thermal inspections is crucial. Additionally, the complex inner structure of wind turbine blades in comparison to other objects and buildings require a specific method referencing the individual rotor blades to each other. This allows the distinction between the thermal response of design-specific structural features and damages or irregularities between the three blades. We show thermal signatures of damage in rotor blades and contrast them with structural characteristics by comparing the three blades. In addition to measurements in industrial environments, laboratory measurements are shown and compared to simulations. The long-term goal is to simulate the influence of different weather parameters and thus gain a better understanding of measurements in the field. The results shown here can be seen as one step towards industrial application. T2 - SPIE Defense + Commercial Sensing CY - Orlando, Florida, USA DA - 03.04.2022 KW - Passive thermography KW - Wind energy KW - FEM simulations PY - 2022 DO - https://doi.org/10.1117/12.2618740 VL - 12109 SP - 1 EP - 8 PB - Society of Photo-Optical Instrumentation Engineers (SPIE) AN - OPUS4-54943 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stamm, Michael T1 - Weather-dependent passive thermography of unheated wind turbine blades N2 - Up to now, the inspection of wind turbines with industrial climbers has been considered ”state of the art”. However, ever-larger wind turbines and advancing digitization make modern and automated inspection methods indispensable. Passive thermography can serve as such a digital and atomized method while it is well known for its applications in the inspection of buildings or electrical circuits. However, its application relies on thermal gradients in the inspected object such that a temperature contrast exists between damaged and sound areas. This also holds for unheated structures like rotor blades of wind turbines which show no intrinsic temperature gradient and can hardly be heated. Under certain weather conditions with sufficient solar loading and diurnal temperature variations, passive thermography is suitable for the in-service inspection of rotor blades. However, for a reliable use of passive thermography on ”thermal passive” components, the incorporation of these environmental conditions in the planning and evaluation of thermal inspections is crucial. Additionally, the complex inner structure of wind turbine blades in comparison to other objects and buildings require a specific method referencing the individual rotor blades to each other. This allows the distinction between the thermal response of design-specific structural features and damages or irregularities between the three blades. We show thermal signatures of damage in rotor blades and contrast them with structural characteristics by comparing the three blades. In addition to measurements in industrial environments, laboratory measurements are shown and compared to simulations. The long-term goal is to simulate the influence of different weather parameters and thus gain a better understanding of measurements in the field. The results shown here can be seen as one step towards industrial application. T2 - Defense + Commercial Sensing 2022 CY - Orlando, Florida, USA DA - 3.4.2022 KW - Passive thermography KW - Wind energy KW - FEM simulations PY - 2022 UR - https://spie.org/defense-commercial-sensing/presentation/Weather-dependent-passive-thermography-of-unheated-wind-turbine-blades/12109-19?SSO=1 AN - OPUS4-54944 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hicke, Konstantin T1 - Distributed fiber optic sensing @BAM N2 - Research and developement activities of BAM regarding Distributed Fiber Optic Sensing are portrayed using exemplary previous and current projects. Shown results pertain to distributed acoustic sensing (DAS), distributed temperagture sensing (DTS) and distributed strain sensing (DSS). T2 - Seismic seminar FU Berlin (group Prof. Shapiro) CY - Online meeting DA - 15.09.2022 KW - Distributed fiber optic sensing KW - Distributed acoustic sensing KW - Distributed temperature sensing KW - Distributed strain sensing KW - Infrastructure monitoring PY - 2022 AN - OPUS4-55721 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stamm, Michael T1 - Towards automated passive thermography of wind turbine blades N2 - Up to now, the inspection of wind turbines by industrial climbers has been considered "state of the art". However, many aspects like ever-larger wind turbines, minimizing the risk for man and machine and the advancing digitalization make modern and automated inspection methods indispensable. A particular interest here is contactless and remote methods that can be used with drones instead of climbing robots. The work presented here contributes to the long-term goal of making autonomous and advanced inspections of wind turbine rotor blades using drones ready for industrial use. Besides visual inspection, only a few inspection methods are capable of non-contact inspection on an industrial scale. Passive thermography can serve as such a contactless and digital inspection method and is well known for its applications in the inspection of buildings or electrical circuits. It can even sense both near-surface and subsurface defects. The sensitivity to subsurface defects makes one advantage of thermography over visual inspections. As a digital inspection method, it is generally also more objective and offers more comparability. For example, defects and their extent can be easily monitored and compared over time. However, its industrial application relies on thermal gradients in the inspected object such that a temperature contrast exists between damaged and sound areas. This also applies to large unheated structures such as wind turbine rotor blades, which do not have an intrinsic temperature gradient and at the same time cannot be easily heated externally. Under certain weather conditions, a change of the environmental temperature or the solar loading conditions can provide the necessary thermal gradients to make passive thermography viable for the in-service inspection of rotor blades. For a reliable use of passive thermography on "thermal passive" components, the incorporation of these environmental conditions in the planning and evaluation of thermal inspections is crucial. Compared to many other objects and buildings, wind turbine blades have varying and often unknown complex internal structures depending on the model. A special method is therefore required, that can be used independently of the internal structure of the blades and that relates the individual thermograms of the three rotor blades to each other. This allows the distinction between the thermal response of design-specific structural features and damages or irregularities between the three blades. In this work we present thermal signatures of rotating in-service rotor blades taken under industrial relevant conditions. These thermograms show surface and subsurface damages and irregularities which we contrast with structural design features by referencing the three blades to each other. In addition, we examine the strong influence of different weather conditions on the inspection results. A direct comparison of measured results with inspection reports from industrial climbers serves as a benchmark. T2 - EERA DeepWind conference CY - Trondheim, Norway DA - 19.01.2022 KW - Thermography KW - Wind energy KW - Passve IR KW - Rotor blades KW - Maintenance PY - 2022 AN - OPUS4-55818 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stamm, Michael T1 - Towards the in-service blade inspection by ground-based passive thermography N2 - Until today, the optical inspection of rotor blades by industrial climbers is considered state of the art. However, both more and larger rotor blades and the increasing digitalization of maintenance work make modern inspection methods increasingly necessary. In this context, passive thermography can serve as a useful digital technique for in-service inspection of wind turbine blades. Unlike active thermography, this inspection method does not require an active heat source but takes advantage of heating by the sun and diurnal temperature fluctuations. This allows inspections from the ground during operation and does not require shutting down the wind turbine. However, an inspection with passive thermography is highly weather dependent. Thus, the already weak thermal signatures formed due to internal structures and possible internal damage are only strong enough under certain weather conditions. To obtain meaningful inspection results despite the relatively small thermal differences between intact and defective components, three aspects are crucial: 1. Measurements should be taken at the time of optimum weather conditions. It must be kept in mind that different internal damage will be revealed by thermal signatures under different weather conditions. 2. The thermal signature of the rotor blades, including possible damages, must be simulated with FEM simulations. In this way, the influence of different weather conditions can be predicted but also understood in the aftermath. 3. The temperature differences between identically designed and assembled rotor blades must be considered to analyze variations between blades. This work will address all these aspects and show, based on field measurements under industrial conditions (exemplarily shown in figure 1), laboratory measurements and FEM simulations, which steps must be taken to establish passive thermography as an industrial inspection method. T2 - EERA SP7 Rotor Blade workshop CY - Roskilde, Denmark DA - 23.06.2022 KW - Thermography KW - Wind energy KW - Maintenance KW - Rotor blades KW - Passive IRT PY - 2022 AN - OPUS4-55819 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stamm, Michael T1 - In situ Charakterisierung von Reparaturen in GFK Schalenstrukturen mittels Lockin Thermografie und Felddehnungsmessungen N2 - Die tiefgreifende Reparatur von Faserverbundwerkstoffen stellt durch deren inneren Aufbau eine besondere Herausforderung dar, die unter anderem bei der Instandhaltung von Rotorblättern von Windkraftanlagen zum Tragen kommt. Um die Reparaturen von Rotorblattschalen zu untersuchen und zu optimieren, wurden an der BAM Sandwich-Schalenprüfkörper aus Glasfaserkunststoff (GFK) entwickelt. Nachdem in diese Schalenprüfkörper Modell-Reparaturen eingebracht wurden, werden zyklische mechanische Ermüdungsversuche bis zum Bruch durchgeführt. Vorrangiges Ziel ist es, den Einfluss verschiedener Reparaturvariablen auf die Ermüdungslebensdauer der Struktur zu verstehen, sowie die stabilste Reparaturmethode zu bestimmen. Während der zyklischen Lastversuche wurden regelmäßig in-situ Messungen mit einer Thermografie Kamera und einem optischen Felddehnungsmesssystem durchgeführt. Durch beide Messmethoden lassen sich Eigenschaften der Probekörper zeitlich und räumlich aufgelöst darstellen. Während die Felddehnungsmessungen Aufschluss über die Verformung an der Oberfläche geben, erfasst die thermische Inspektion Temperaturänderungen an der Oberfläche. Besonders die thermografischen Messwerte bilden hier das oberflächennahe Volumen ab, in dem sich Temperaturänderungen an der Oberfläche abzeichnen. Die Messergebnisse beider Systeme stellen also verschiede aber korrelierte Parameter dar. Denn die zyklische Belastung (Bewegung) ruft eine periodische Temperaturänderung im Bauteil hervor. Dieser so genannte Thermoeleastische Effekt kann durch eine Lockin-Analyse der Temperaturtransienten (Temperaturverläufe) nachgewiesen werden. Die räumliche Darstellung der thermischen Effekte lässt Rückschlüsse auf die tatsächliche Lastverteilung im Probekörpervolumen zu. Darüber hinaus führen nichtelastische Verformungen zu einer zusätzlichen Wärmefreisetzung, die durch geeignete Auswerteverfahren ebenfalls nachgewiesen werden können. Entsprechende Hot-Spots in der räumlichen Verteilung erlauben eine frühzeitige Erkennung besonders belasteter Bereiche lange vor dem eigentlichen Bauteil-Versagen. Das gestattet die Lokalisierung des Initial-Schadens, was mit der numerischen Spannungsanalyse korreliert werden kann und die Entwicklung und Bewertung verschiedener Reparaturstrategien. T2 - DGZfP Jahrestagung 2022 CY - Kassel, Germany DA - 23.05.2022 KW - Lockin Thermografie KW - GFK KW - NDT KW - ZfP PY - 2022 AN - OPUS4-55823 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lay, Vera T1 - Das Themenfeldprojekt SealWasteSafe im Überblick N2 - Das Projekt SealWasteSafe verbessert Werkstofftechnik, Prüfverfahren und Überwachungsmethoden für sichere Verschlussbauwerke in Endlagern. Dieser Überblick fasst die laufenden Arbeiten in folgenden Bereichen zusammen: 1) Materialentwicklung und Dauerhaftigkeit; 2) Überwachung; 3) Inspektion. T2 - Online-Workshop „Dauerhafte Verschlussbauwerke für Endlager“ CY - Online meeting DA - 14.02.2022 KW - SealWasteSafe KW - Salzbeton KW - Verschlussbauwerke KW - Monitoring KW - Inspektion KW - Ultraschall PY - 2022 AN - OPUS4-55089 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Effner, Ute T1 - Ultraschall-Messungen an in-situ-Abdichtbauwerken mit neu entwickelten Messtechniken N2 - Neue Ultraschall-Messsysteme (LAUS, Bohrlochsonde) haben ihre Funktionstüchtigkeit unter Beweis gestellt. Ergebnisse aus den Messungen konnten verifiziert werden. Standard-Mess- und –Auswerteverfahren müssen für Spritzbeton weiterentwickelt und angepasst werden. Mit sämtlichen Messmethoden konnten großflächige Risse detektiert werden. Messungen mit der Bohrlochsonde und LAUS sind zur Qualitätssicherung geeignet. T2 - Workshop zum TFP-SealWasteSafe CY - Online meeting DA - 14.02.2022 KW - Abdichtbauwerk / Verschlussbauwerk KW - Zerstörungsfreie Prüfung KW - Ultraschall-Echoverfahren PY - 2022 AN - OPUS4-55104 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hicke, Konstantin T1 - Distributed fiber optic radiation sensors for nuclear applications N2 - Advantages and underlying principles of distributed fiber optic radiation sensing are discussed. Differences with regard to dose measurement range and resolution between glass optical fiber based sensing and polymer optical fiber based sensing are outlined. T2 - DGZfP SMIRT26 Laborbesuch (BAM) CY - Berlin, Germany DA - 10.07.2022 KW - Distributed fiber optic sensing KW - Fiber optic radiation monitoring KW - Distributed fiber optic radiation sensing PY - 2022 AN - OPUS4-55264 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lay, Vera T1 - Geophysikalische Methoden für die Zerstörungsfreie Prüfung im Bauwesen N2 - Im Rahmen des Seminars "Angewandte Forschungsthemen (SAFT)" am Institut für Geowissenschaften der Christian-Albrechts-Universität zu Kiel werden verschiedene geophysikalische Methoden vorgestellt, die bei der zerstörungsfreien Prüfung im Bauwesen zum Einsatz kommen. Neben einem Überblick der Arbeiten an der BAM im Allgemeinen und dem Fachbereich im Besonderen geht es vor allem um den Einsatz von Ultraschallmethoden. Drei wesentliche Schwerpunkte werden dabei beleuchtet: 1) (Geophysikalische) Antworten auf Herausforderungen bei Ultraschall-Anwendungen 2) Material research and multi-sensory monitoring for concrete sealing structures in rock salt unterground repositories (Projekt SealWasteSafe) und 3) Untersuchung von Spritzbeton-Probekörpern unter Tage mit Ultraschall zur Qualitätssicherung von Verschlussbauwerken. Insgesamt werden diverse Möglichkeiten für die Geophysik für Forschung und Studierende im Bereich der zerstörungsfreien Prüfung im Bauwesen aufgezeigt. T2 - Seminar Angewandte Forschungsthemen CY - Kiel, Germany DA - 14.06.2023 KW - SealWasteSafe KW - Ultraschall KW - Verschlussbauwerke KW - Abbildungsverfahren PY - 2023 AN - OPUS4-57828 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Friedrich, Christian T1 - Eignungsprüfungen geophysikalischer Sensoren zur Rissdetektion an Demonstrationsbauwerken N2 - Bei der Betonage von Abdichtbauwerken können Temperaturen bis 110 °C und hohe Drücke bis 5 MPa erreicht werden. Mittels Technikumsversuchen wurde nachgewiesen, dass Mikroakustik- und Ultraschallsensoren zum Einbau in Demonstrationsbauwerke geeignet sind. Die Untersuchungen wurden bei der BAM (Bundesanstalt für Materialforschung und -prüfung) in Berlin durchgeführt. Es ist vorgesehen, die Sensoren in Morsleben am Demonstrationsbauwerk im Anhydrit einzusetzen. T2 - 84. Jahrestagung der Deutschen Geophysikalischen Gesellschaft CY - Jena, Germany DA - 10.03.2024 KW - Ultraschall KW - Eignungsprüfung KW - Risse KW - Abdichtbauwerk KW - Anhydrit PY - 2024 AN - OPUS4-59772 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Chaudhuri, Somsubhro T1 - EvalTherm - Weather-dependent passive thermography and thermal simulation of in-service wind turbine blades N2 - To cope with the increase in the manufacturing and operation of wind turbines, wind farm operators need inspection tools that are able to provide reliable information while keeping the downtime low. Current inspection techniques require to stop the wind turbine. This work presents the current progress in the project EvalTherm, in which passive thermography is evaluated as a possible non-destructive inspection tool for operational wind turbine blades (WTBs). A methodology to obtain thermal images of rotating WTBs has been established in this project. However, the quality of the results is heavily dependent on various aspects such as weather conditions, information on the inspected WTB, damage history, etc. In this work, a section of a used WTB is simulated using finite-element modelling (FEM) as well as experimentally tested for evaluating the accuracy of the model. Such a model will provide insight into the potential thermal response of a certain structure (with specific material properties) in given weather (boundary) conditions. The model is able to provide satisfactory predictions of the thermal response of the structure, as well as indicate what thermal contrast(s) result from artificial defects introduced in the structure. T2 - WindEurope Annual Event 2023 CY - Copenhagen, Denmark DA - 25.04.2023 KW - FEM KW - Thermografie KW - Wind turbine rotor blades KW - Windenergie anlage rotorblätter PY - 2023 AN - OPUS4-58274 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sablowski, J. A1 - Lugovtsova, Yevgeniya A1 - Bulling, Jannis A1 - Kupsch, C. T1 - Experimental Study of Ultrasonic Guided Waves in a Bipolar Plate of a Fuel Cell N2 - Water management in proton-exchange membrane fuel cells (PEMFCs) is critical for efficient operation. However, in-situ measurements of the water distribution in an operating PEMFC are challenging. In this study, we investigate key aspects of ultrasonic guided wave (UGW) propagation through the bipolar plate of a PEMFC using 3D scanning laser Doppler vibrometry (3D LDV). Our results provide insights for the design and optimization of UGW-based sensor systems for water detection in PEMFCs. T2 - 2023 IEEE International Ultrasonics Symposium (IUS) CY - Montreal, QC, Canada DA - 03.09.2023 KW - Ultrasonic guided waves KW - Laser Doppler vibrometry KW - Fuel cells KW - Water management PY - 2023 DO - https://doi.org/10.1109/IUS51837.2023.10307327 SP - 1 EP - 4 PB - IEEE AN - OPUS4-59540 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ghasem Zadeh Khorasani, Media T1 - Federated SHM: a Novel Collaborative ML Approach to Overcome Data Scarcity and Data Privacy Concerns in StructuralHealth Monitoring N2 - The deployment of machine learning (ML) and deep learning (DL) in structural health monitoring (SHM) faces multiple challenges. Foremost among these is the insufficient availability of extensive high-quality data sets essential for robust training. Within SHM, high-quality data is defined by its accuracy, relevance, and fidelity in representing real-world structural scenarios (pristine as well as damaged). Although methods like data augmentation and creating synthetic data can add to datasets, they frequently sacrifice the authenticity and true representation of the data. Sharing real-world data encapsulating true structural and anomalous scenarios offers promise. However, entities are often reluctant to share raw data, given the potential extraction of sensitive information, leading to trust issues among collaborating entities. Our study introduces a novel methodology leveraging Federated Learning (FL) to navigate these challenges. Within the FL framework, models are trained in a decentralized manner across different entities, preserving data privacy. In our research, we simulated several scenarios and compared them to traditional local training methods. Employing guided wave (GW) datasets, we distributed the data among different parties (clients) using IID (independent, identically distributed or in other words, statistically identical) mini batches of dataset, as well as non-IID configurations. This approach mirrors real-world data distribution among varied entities, such as hydrogen refueling stations. In our methodology, the initial round involves individualized training for each client using their unique datasets . Subsequently, the model parameters are sent to the FL server, where they are averaged to construct a global model. In the second round, this global model is disseminated back to the clients to aid in predictive tasks. This iterative process continues for several rounds to reach convergence. Our findings distinctly highlight the advantages of FL over localized training, evidenced by a marked improvement in prediction accuracy . This research underscores the potential of FL in GW-based SHM, offering a remedy to similar challenges tied to data scarcity in other SHM approaches and paving the way for a new era of collaborative, data-centric monitoring systems. T2 - QI Digital Forum CY - Berlin, Germany DA - 10.10.2023 KW - Machine learning KW - Federated learning KW - Structural health monitoring KW - Artificial intelligence KW - Hydrogen safety KW - Data privacy PY - 2023 AN - OPUS4-59415 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Charmi, Amir A1 - Mustapha, Samir A1 - Yilmaz, Bengisu A1 - Heimann, Jan A1 - Prager, Jens T1 - A Machine Learning Based-Guided Wave Approach for Damage Detection and Assessment in Composite Overwrapped Pressure Vessels N2 - The applications of composite overwrapped pressure vessels (COPVs) in extreme conditions, such as storing hydrogen gases at very high pressure, impose new requirements related to the system's integrity and safety. The development of a structural health monitoring (SHM) system that allows for continuous monitoring of the COPVs provides rich information about the structural integrity of the component. Furthermore, the collected data can be used for different purposes such as increasing the periodic inspection intervals, providing a remaining lifetime prognosis, and also ensuring optimal operating conditions. Ultimately this information can be complementary to the development of the envisioned digital twin of the monitored COPVs. Guided waves (GWs) are preferred to be used in continuous SHM given their ability to travel in complex structures for long distances. However, obtained GW signals are complex and require advanced processing techniques. Machine learning (ML) is increasingly utilized as the main part of the processing pipeline to automatically detect anomalies in the system's integrity. Hence, in this study, we are scrutinizing the potential of using ML to provide continuous monitoring of COPVs based on ultrasonic GW data. Data is collected from a network of sensors consisting of fifteen Piezoelectric (PZT) wafers that were surface mounted on the COPV. Two ML algorithms are used in the automated evaluation procedure (i) a long short-term memory (LSTM) autoencoder for anomaly detection (defects/impact), and (ii) a convolutional neural network (CNN) model for feature extraction and classification of the artificial damage sizes and locations. Additional data augmentation steps are introduced such as modification and addition of random noise to original signals to enhance the model's robustness to uncertainties. Overall, it was shown that the ML algorithms used were able to detect and classify the simulated damage with high accuracy. T2 - 13th European Conference on Non-Destructive Testing (ECNDT) 2023 CY - Lisbon, Portugal DA - 03.07.2023 KW - Machine learning KW - Structural health monitoring KW - COPV KW - Guided waves KW - Damage localization PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-590789 DO - https://doi.org/10.58286/28079 SN - 2941-4989 VL - 1 IS - 1 SP - 1 EP - 6 PB - NDT.net CY - Mayen AN - OPUS4-59078 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mustapha, S. A1 - Yilmaz, Bengisu A1 - Heimann, Jan A1 - Brence, Blaz A1 - Prager, Jens T1 - Guided Waves Propagation in Composite Overwrapped Pressure Vessel N2 - The application of composite overwrapped pressure vessels (COPV) to store hydrogen and other compressed gases, especially when operating at high pressures, imposed the need for an innovative and reliable approach to ensure the safe operation of the system. Continuous structural health monitoring (SHM) based on ultrasonic guided waves (GWs) is a promising approach due to the ability of the wave to propagate for long distances and go around complex structures, moreover the high sensitivity to various failure modes such as delamination, matrix cracking and debonding. In this study, we scrutinize the behavior of (GWs) within the COPV using a network of PZT elements that are used for excitation and sensing. A laser doppler vibrometer (LDV) was also used to scan the surface of the vessel in various directions. L(0,1) and L(0,2) were observed in the captured signal. The L(0, 2) appeared to be a dominant mode in the COPV and was capable of propagating along the entire length and maintaining a good signal-to-noise ratio. The L(0,2) mode maintained the same phase velocity when it is captured at various excitation angles (0, 45, and 90 degrees). The reduced effect of the orthotropy of the materials on the propagating waves is an important result as it will reduce the complexity in data processing when performing damage identification. T2 - 13th. European Conference on Non-Destructive Testing (ECNDT) CY - Lisbon, Portugal DA - 03.07.2023 KW - Composite Overwrapped Pressure Vessels KW - Guided Waves KW - Laser Doppler Vibrometer KW - Structural Health Monitoring KW - Sensors Placement PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-591081 DO - https://doi.org/10.58286/28068 SN - 2941-4989 VL - 1 IS - 1 SP - 1 EP - 6 PB - NDT.net CY - Mayen AN - OPUS4-59108 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yilmaz, Bengisu A1 - Heimann, Jan A1 - Mustapha, S. A1 - Charmi, Amir A1 - Prager, Jens T1 - Guided wave ultrasonic feature determination in Type IV composite overwrapped pressure vessels towards the digital twin N2 - The digitalization of quality control processes and the underlying data infrastructures for safety relevant components, such as hydrogen pressure vessels, plays a significant role in the transition towards Industry 4.0. In the current safety regulations for hydrogen pressure vessels, there is no established concept for structural health monitoring. The development of a reliable structural health monitoring methodology for monitoring the structural integrity of pressure vessels enables a fast-forward transition from personnel- and costintensive recurring inspections, a.k.a. periodic maintenance, to predictive maintenance. In the work presented; we investigated the application of ultrasonic guided wave propagation to monitor and assess the condition of Type IV composite overwrapped pressure vessel (COPV). A sensor network of fifteen piezo-electric wafers is placed on the carbon fibre reinforced composite cylinder. Five different artificial damage configurations are created by gluing two different weight blocks on three different locations. The database containing measured guided wave data sets is enriched by two different boundary conditions. We utilized an open-source software, openBIS labnotebook, to store and analyse experimental datasets. The guided wave ultrasonic signals were investigated and analysed by using commonly used ultrasonic features (e.g., amplitude, frequency, time of flight) as well as non-traditional time-series features (kurtosis, skewness, variance). The features were used to calculate damage index and the detection performance for the results has been evaluated. The results suggest that both traditional and non-traditional features assume significant importance in artificial damage detection. The future works will additionally involve the impacts of operational conditions, such as periodic pressure variations temperature loadings as well as material degradations. T2 - 13th European Conference on Non-Destructive Testing (ECNDT) CY - Lisbon, Portugal DA - 03.07.2023 KW - Industry 4.0 KW - Composite overwrapped pressure vessels KW - Structural health monitoring KW - Ultrasonic guided waves KW - Predictive maintenance PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-591094 DO - https://doi.org/10.58286/28072 SN - 2941-4989 VL - 1 IS - 1 SP - 1 EP - 6 PB - NDT.net CY - Mayen AN - OPUS4-59109 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heimann, Jan T1 - Guided Waves Propagation in Composite Overwrapped Pressure Vessel N2 - The application of composite overwrapped pressure vessels (COPV) to store hydrogen and other compressed gases, especially when operating at high pressures, imposed the need for an innovative and reliable approach to ensure the safe operation of the system. Continuous structural health monitoring (SHM) based on ultrasonic guided waves (GWs) is a promising approach due to the ability of the wave to propagate for long distances and go around complex structures, moreover the high sensitivity to various failure modes such as delamination, matrix cracking and debonding. In this study, we scrutinize the behavior of (GWs) within the COPV using a network of PZT elements that are used for excitation and sensing. A laser doppler vibrometer (LDV) was also used to scan the surface of the vessel in various directions. L(0,1) and L(0,2) were observed in the captured signal. The L(0,2) appeared to be a dominant mode in the COPV and was capable of propagating along the entire length and maintaining a good signal-to-noise ratio. The L(0,2) mode maintained the same phase velocity when it is captured at various excitation angles (0, 45, and 90 degrees). The reduced effect of the orthotropy of the materials on the propagating waves is an important result as it will reduce the complexity in data processing when performing damage identification. T2 - European Conference on Non-Destructive Testing (ECNDT) CY - Lisbon, Portugal DA - 03.07.2023 KW - Structural Health Monitoring KW - Guided Waves KW - Composite Overwrapped Pressure Vessel KW - Laser Doppler Vibrometer KW - Sensor Placement PY - 2023 AN - OPUS4-58873 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Charmi, Amir T1 - Closing the gap between simulation and experiment using autoencoders N2 - Structural Health Monitoring (SHM) mittels geführter Ultraschallwellen ermöglicht eine kontinuierliche Überwachung komplexer Bauteile und liefert umfangreiche Informationen über deren strukturelle Integrität. Die aufgezeichneten Signale sind jedoch komplex und werden daher zunehmend mittels KI verarbeitet, um Anomalien in der Systemintegrität automatisch zu erkennen. Eine Herausforderung dabei ist jedoch das Trainieren solcher KI-Modelle, da dafür große Mengen an Trainingsdaten inklusive diverser Schadensfälle benötigt werden, um eine hohe Genauigkeit und Zuverlässigkeit zu gewährleisten. Experimentelle Generierung dieser Daten ist wegen des enormen Zeit- und Kostenaufwands nicht möglich. Eine Alternative hierfür bieten die numerischen Simulationen, da dadurch Trainingsdaten für beliebige Anzahl an Schadenskonfigurationen erzeugt werden können. Das Hauptproblem dabei ist jedoch die Abweichung zwischen den experimentellen und simulierten Daten (durch z.B. Abweichungen bei der Geometrie, Randbedingungen oder Materialparameter). Um diese Abweichungen zu reduzieren bzw. zu eliminieren, wird ein KI-Modell mit einer Autoencoder-Decoder Architektur vorgestellt, die mittels eines Experiments kalibriert werden kann und anschließend in der Lage ist, die Genauigkeit der Simulationsergebnisse nachträglich zu erhöhen. T2 - 28. DEGA-Workshop „Physikalische Akustik“ - Maschinelles Lernen in der physikalischen Akustik CY - Bad Honnef, Germany DA - 19.10.2023 KW - KI KW - SHM KW - Simulation KW - Geführte Ultraschallwellen PY - 2023 AN - OPUS4-58686 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Charmi, Amir T1 - A Machine Learning Based-Guided Wave Approach for Damage Detection and Assessment in Composite Overwrapped Pressure Vessels N2 - The applications of composite overwrapped pressure vessels (COPVs) in extreme conditions, such as storing hydrogen gases at very high pressure, impose new requirements related to the system's integrity and safety. The development of a structural health monitoring (SHM) system that allows for continuous monitoring of the COPVs provides rich information about the structural integrity of the component. Furthermore, the collected data can be used for different purposes such as increasing the periodic inspection intervals, providing a remaining lifetime prognosis, and also ensuring optimal operating conditions. Ultimately this information can be complementary to the development of the envisioned digital twin of the monitored COPVs. Guided waves (GWs) are preferred to be used in continuous SHM given their ability to travel in complex structures for long distances. However, obtained GW signals are complex and require advanced processing techniques. Machine learning (ML) is increasingly utilized as the main part of the processing pipeline to automatically detect anomalies in the system's integrity. Hence, in this study, we are scrutinizing the potential of using ML to provide continuous monitoring of COPVs based on ultrasonic GW data. Data is collected from a network of sensors consisting of fifteen Piezoelectric (PZT) wafers that were surface mounted on the COPV. Two ML algorithms are used in the automated evaluation procedure (i) a long short-term memory (LSTM) autoencoder for anomaly detection (defects/impact), and (ii) a convolutional neural network (CNN) model for feature extraction and classification of the artificial damage sizes and locations. Additional data augmentation steps are introduced such as modification and addition of random noise to original signals to enhance the model's robustness to uncertainties. Overall, it was shown that the ML algorithms used were able to detect and classify the simulated damage with high accuracy. T2 - European Conference on Non-Destructive Testing (ECNDT) CY - Lisbon, Portugal DA - 03.07.2023 KW - Guided waves KW - Structural Health Monitoring KW - Machine learning KW - Damage localization KW - COPV PY - 2023 AN - OPUS4-58687 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Melzer, Michael A1 - Nattuveettil, Keerthana T1 - Digital Calibration Certificates: Transforming Efficiency and Safety in Hydrogen Refuelling Station N2 - Digital Certificates have emerged as a pivotal element in automation and digitalisation. This presentation highlights the added value of a digitalised metrology, its impact on the workflows on the calibration service providing and receiving side as well as their significance in enhancing the quality infrastructure. An overview of digital calibration certificates (DCC) for temperature sensors, including their structure and role in establishing trust in hydrogen refuelling stations (HRS), will be discussed. Additionally, it explores the impact of DCC on optimising efficiency in the hydrogen refuelling process. Exploring the paradigm shift brought about by Industry 4.0, where machines possess the ability to autonomously interpret digital certificate data, leads to streamlined safety checks and reduced human intervention. We will discuss how automated verification of machine-readable certificates contributes to maintaining and elevating safety standards over human-readable certificates. Furthermore, we will take a deep dive into the application of DCCs in HRS, showcasing how they enhance operational efficiency, accuracy, and maintenance by enabling real-time monitoring and adjustment of process data. By exploring the interdependent relationship between digital certificates, machine-readable environments, and HRS optimisation, this presentation will provide valuable insights into harnessing cutting-edge technologies to create a safer, more efficient, and technologically empowered hydrogen refuelling process. T2 - H2Safety@BAM : Hydrogen Colloquium CY - Online meeting DA - 06.09.2023 KW - Digital Calibration Certificate KW - Digitalization KW - Digital Traceability KW - QI-Digital KW - Hydrogen Infrastructure PY - 2023 UR - https://www.bam.de/Content/DE/Standardartikel/Themen/Energie/Wasserstoff/wasserstoff.html AN - OPUS4-58353 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Chaudhuri, Somsubhro T1 - Weather-dependent passive thermography and thermal simulation of in-service wind turbine blades N2 - The thermographic methods NDT division of BAM is aiming to develop a wind turbine blade (WTB) inspection tool using infrared thermographic scanning of operational wind turbines in the project EvalTherm. T2 - WindEurope Annual Event 2023 CY - Copenhagen, Denmark DA - 25.04.2023 KW - FEM KW - Thermografie KW - Wind turbine rotor blades KW - Windenergie anlage rotorblätte PY - 2023 AN - OPUS4-58275 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chaudhuri, Somsubhro A1 - Stamm, Michael A1 - Krankenhagen, Rainer T1 - Weather-dependent passive thermography and thermal simulation of in-service wind turbine blades N2 - . To cope with the increase in the manufacturing and operation of wind turbines, wind farm operators need inspection tools that are able to provide reliable information while keeping the downtime low. Current inspection techniques require to stop the wind turbine. This work presents the current progress in the project EvalTherm, in which passive thermography is evaluated as a possible non-destructive inspection tool for operational wind turbine blades (WTBs). A methodology to obtain thermal images of rotating WTBs has been established in this project. However, the quality of the results is heavily dependent on various aspects such as weather conditions, information on the inspected WTB, damage history, etc. In this work, a section of a used WTB is simulated using finite-element modelling (FEM) as well as experimentally tested for evaluating the accuracy of the model. Such a model will provide insight into the potential thermal response of a certain structure (with specific material properties) in given weather (boundary) conditions. The model is able to provide satisfactory predictions of the thermal response of the structure, as well as indicate what thermal contrast(s) result from artificial defects introduced in the structure. T2 - WindEurope Annual Event 2023 CY - Copenhagen, Denmark DA - 25.04.2023 KW - FEM KW - Thermografie KW - Wind turbine rotor blades KW - Windenergie Anlage Rotorblätter PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-582777 DO - https://doi.org/10.1088/1742-6596/2507/1/012025 VL - 2507 SP - 1 EP - 12 PB - IOP Publishing Ltd. AN - OPUS4-58277 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Chaudhuri, Somsubhro T1 - EvalTherm - Detectability of internal defects in wind turbine rotor blades using passive infrared thermography N2 - A steady increase of wind energy infrastructure brings along a challenge of maintaining and operating wind turbines (WT) with its multiple components. Inspection of wind turbine rotor blades (WTB) is an important part of maintaining the overall health and safety of a WT. It involves visually or mechanically examining the blades for signs of damage or wear that could affect their performance and structural integrity of the entire WT. A WTB is a complex structure due to its ever-increasing scale (going beyond 100 m for a 16 MW WT) as well as multi-material construction. Passive infrared thermography offers an alternative to contact- or proximity-based inspection techniques currently in use such as visual inspection performed by technical personnel (using a lift or a drone) and involves looking for signs of damage on the surface of the blades, and ultrasonic testing to detect internal defects. In contrast to active thermography, passive thermography uses the sun as source of heat, instead of conventional heat lamps, flash, or laser. An inspection technique to (semi-autonomously) inspect the WTBs of an operating WT from the ground has been developed. Given the optimum thermal contrast (weather conditions for field measurements), external as well as internal features of the WTB can be visualised with appropriate post-processing. The work presented here is part of an ongoing multi-partner project titled “EvalTherm”: the evaluation of passive thermography as a non-destructive inspection tool of WTBs in operation. In this work, artificial defects representative of realistic defects in glass fibre reinforced plastic (GFRP) WTBs are introduced in out-of-service WTB pieces. These are scanned using X-ray computed tomography to obtain a three-dimensional reconstruction to be used as input for finite-element based thermal simulation using COMSOL Multiphysics. The simulation data is compared with infrared thermal inspection of the same WTB section, in order to compare the effect of thermal contrast caused in certain weather conditions. In addition, the influence of defect characteristics such as defect size, morphology, and location on detectability is investigated. Validated simulation models are used to predict thermal signatures of defects along with the optimal thermal contrast. Such simulation models in combination with weather forecast data can assist operators of wind turbine infrastructure to plan passive thermography inspection without the need of dangerous inspection procedures and associated shutdown of energy production. T2 - Wind Energy Science Conference (WESC) 2023 CY - Glasgow, Scotland DA - 23.05.2023 KW - FEM KW - Thermografie KW - Wind turbine rotor blades KW - Windenergie anlage rotorblätter KW - Thermography PY - 2023 AN - OPUS4-58283 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mehri Sofiani, F A1 - Chaudhuri, Somsubhro A1 - Elahi, S.A. A1 - Hectors, K. A1 - De Waele, W. T1 - Quantitative Analysis of the Correlation between Geometric Parameters of Pits and Stress Concentration Factors for a Plate Subject to Uniaxial Tensile Stress N2 - The offshore environment is inherently corrosive. Consequently, pits may nucleate on exposed steel surfaces. Corrosion pits can be a source of crack initiation when the structure is subject to fatigue loading. The criticality of a corrosion pit with respect to the structural integrity depends on its shape and size and can be quantified using a stress concentration factor (𝐾𝑡). In this work, a parametric 3D finite element model is developed to perform stress analysis of a pitted plate subjected to uniaxial tensile stress. The model is used for an extensive parameter study in which 𝐾𝑡 is determined for various pit configurations. It is demonstrated that each one of the geometrical parameters holds a substantial influence on the location of the Most Critical Region (MCR). It is shown that 𝐾𝑡 increases as the pit gets narrower. Pits with an elliptical mouth yield higher 𝐾𝑡 values when the angle between the load direction and the pit mouth major axis increases. Moreover, 𝐾𝑡 increases with the increase in the localized thickness loss which is more pronounced for relatively wider pits. Finally, a regression model is presented for estimating 𝐾𝑡 based on the geometric parameters of a pit. KW - FEM KW - Corrosion KW - SCF KW - Pitting corrosion PY - 2023 DO - https://doi.org/10.1016/j.tafmec.2023.104081 SN - 0167-8442 VL - 127 SP - 1 EP - 27 PB - Elsevier Ltd. AN - OPUS4-58284 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stamm, Michael T1 - Semi-automated detection of rain erosion damages on turbine blades with passive thermography and AI image processing N2 - The European Green Deal and the global fight against climate change call for more and larger wind turbines in Europe and around the world. To meet the increasing demand for maintenance and inspection, partly autonomous methods of remote inspection are increasingly being developed in addition to industrial climbers performing the inspection. Rotor blades are exposed to extreme weather conditions throughout their lifetime of 20 years, and the leading edge erodes over time. These erosion damages change the aerodynamic features of blades and can cause structural damages. The estimated annual energy production (AEP) losses caused by erosion damages are between 0.5% and 2% per year. The classification of the severity of a rain erosion damage and the quantification of the resulting AEP losses for cost efficient repair and maintenance efforts and improved power production of wind turbines are subject of scientific research. For the inspection of wind turbine rotor blades, passive thermography is an option that has been used to detect both internal damage [3, 4] as well as erosion on the surface [5, 6]. The advantage is that, given suitable boundary conditions, not only the rain erosion damage itself but also temperature differences caused by the resulting turbulences can be observed on the surface of the blade. Turbulences reduce the efficiency of the rotor blades and result in AEP losses. Optimised thermography inspections can contribute to detect and to evaluate rain erosion damages. The thermal inspection lasts 10 minutes per turbine and is performed while the turbine is in full operation, avoiding downtime and lost opportunities for the turbine owner which are usually caused by conventional blade inspections. The timely inspection procedure is complemented by an automatic data evaluation and results in a considerable number of inspected wind turbines in a certain period of time. A fully convolutional network (FCN) is implemented for the automated evaluation of thermal images. In the presented study, more than 1000 thermographic images of blades were annotated, augmented and used to train and test the FCN. The aim is the precise marking of thermal signatures caused by erosion damage at the leading edge. The area size of the detected temperature difference caused by turbulences was used to identify and categorise damages. Certain strategies were adopted to group small individual indications as one large damage, in order to develop simplification rules based on realistic thermal imaging resolution. T2 - Wind Energy Science Conference (WESC) 2023 CY - Glasgow, Scotland DA - 23.05.2023 KW - Non-destructive testing KW - Thermography KW - Wind turbine blade PY - 2023 AN - OPUS4-58498 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stamm, Michael T1 - In situ characterisation of GFRP shell structures of wind turbine rotor blades under test using lock-in thermography N2 - The work shown demonstrates the possibility of measuring the load distribution of complex components such as rotor blades in cyclic tests using thermography. This is confirmed in the experiments presented by comparison with DIC measurements. The advantage of thermography is that it does not require any treatment of the test specimens in the setup shown and the measurement procedure can in principle be scaled to large components. In addition, compared to other imaging methods, the actual loads and not the deformation are measured. With a suitable data evaluation by means of Lockin analysis, small loads can be verified in a formative manner. Using the example of model repairs in shell test specimens made of sandwich glass fibre composite material, it is shown that inhomogeneous load distribution due to internal structures can be detected using thermography. T2 - WindEurope Annual Event 2023 CY - Copenhagen, Denmark DA - 25.04.2023 KW - Thermography KW - TSA PY - 2023 AN - OPUS4-58500 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stamm, Michael T1 - Infrared Thermography of wind turbine rotor blades: 3 use cases N2 - Thermography is a widely accepted non-invasive measurement method and is generally used in various areas of the life cycle of infrastructure and machinery. This includes design, production and maintenance. Thermography is particularly suitable for remote inspection of large areas that are difficult to reach. In this presentation, applications of thermography in the field of wind energy will be shown, touching on three explicit examples from rotor blade inspection. Experimental testing and validation: Thermography can measure and visualise the stress distribution on the surface during cyclic tests of rotor blades and rotor blade sections. The so-called thermoelastic stress analysis makes use of special evaluation algorithms (Lockin analysis) of the measurement data and the cyclic loading of components. An advantage of the measurement methods compared to other measurement methods such as strain gauges or digital image correlation is that it does not require any extra treatment or sensoring of the components. In the work shown here, repair methods are optimised and evaluated in cyclic tests on shell test specimens. Operation and maintenance: Rotor blades can be inspected from the ground during operation using passive thermography. Here, the integration of weather forecasts and conditions as input for simulations is crucial and will be demonstrated with some examples from the field. The goal of the ongoing research is to obtain detailed insights into the internal structure of the inspected rotor blades with individual measurements. A specially developed automated measuring system is able to measure a wind turbine (one-sided) within 5 minutes without impacting its operation. Environmental impact: In cases where less strict time and economic constraints apply than in the maintenance of rotor blades in operation, thermography can also be used to realise other inspection processes that take more time. Examples of this are quality control or the characterisation of rotor blades during dismantling. In the latter case, for example, it can be crucial to know which components such as foam, balsa, belt and spar are present in which parts of the blade when dismantling the rotor blades. Long-term measurements (~1-2 h) under suitable weather conditions can provide good insights into the inner structure of the rotor blades, both during disassembly and during quality control before installation. For this purpose, the sun is used as a heat source, which induces a thermal response of the rotor blades. The thermal behaviour of the rotor blades then allows conclusions to be drawn about the internal structure. T2 - EERA DeepWind conference 2023 CY - Trondheim, Norway DA - 18.01.2023 KW - Thermography KW - Wind turbine blade KW - Inspection PY - 2023 AN - OPUS4-58501 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stamm, Michael A1 - Krankenhagen, Rainer T1 - EvalTherm - Weather-dependent passive thermography of unheated wind turbine blades N2 - Evaluation of passive Thermography for the inspection of wind turbine blades. Comparison of passive thermography from the ground with drone-supported images and active thermography. Better understand the influence of weather conditions through field measurements. Development of an inspection planning tool that incorporates weather forecasts. Use FEM simulations to predict thermal contrasts of different damages under different environmental conditions. T2 - Kolloquium CY - Saarbrücken, Germany DA - 28.09.2022 KW - Thermography KW - Wind turbine rotor blades KW - FEM PY - 2022 AN - OPUS4-56913 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lay, Vera T1 - Innovations in cemented waste handling and pre-disposal storage (WP7 project PREDIS) N2 - During the webinar "Dismantling and waste management: a playground for innovation" the innovative aspects of the PREDIS work package "innovations in cemented waste handling and pre-disposal storage" are presented. The webinar is jointly organised by Women in Nuclear Decommissioning (WINDI) and Women in Nuclear Innovation (WINI). The shown innovations include quality assurance (mainly NDE) and monitoring technologies with associated sensor systems, digital twin technology, and appropriate data handling including a decision framework. An overview of the on-going research in the field of pre-disposal waste management in the project Predis (WP7) is summarised. T2 - Webinar "Dismantling and waste management: a great playground for innovation" CY - Online meeting DA - 13.10.2022 KW - Predis KW - Waste management KW - Concrete PY - 2022 AN - OPUS4-56926 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lu, Xin T1 - Introduction to group 8.6 N2 - A brief introduction of group 8.6 and the research work on the application of fiber sensing. T2 - DIU Besuch CY - Berlin, Germany DA - 05.05.2023 KW - Structural health monitoring KW - Distributed fiber sensing KW - Distributed acoustic sensing KW - Practical application PY - 2023 AN - OPUS4-57430 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Chaudhuri, Somsubhro A1 - Stamm, Michael T1 - Infrared thermography of turbulence patterns of operational wind turbine rotor blades supported with high-resolution photography: KI-VISIR Dataset N2 - With increasing wind energy capacity and installation of wind turbines, new inspection techniques are being explored to examine wind turbine rotor blades, especially during operation. A common result of surface damage phenomena (such as leading-edge erosion) is the premature transition of laminar to turbulent flow on the surface of rotor blades. In the KI-VISIR (Künstliche Intelligenz Visuell und Infrarot Thermografie – Artificial Intelligence-Visual and Infrared Thermography) project, infrared thermography is used as an inspection tool to capture so-called thermal turbulence patterns (TTP) that result from such surface contamination or damage. To compliment the thermographic inspections, high-resolution photography is performed to visualise, in detail, the sites where these turbulence patterns initiate. A convolutional neural network (CNN) was developed and used to detect and localise the turbulence patterns. A unique dataset combining the thermograms and visual images of operational wind turbine rotor blades has been provided, along with the simplified annotations for the turbulence patterns. Additional tools are available to allow users to use the data requiring only basic Python programming skills. KW - Reference Data KW - Infrared Thermography KW - Wind energy KW - Dataset PY - 2024 DO - https://doi.org/10.5281/zenodo.13771899 PB - Zenodo CY - Geneva AN - OPUS4-61102 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Charmi, Amir T1 - Application of deep learning for structural health monitoring of a composite overwrapped pressure vessel undergoing cyclic loading N2 - Structural health monitoring (SHM) using ultrasonic-guided waves (UGWs) enables continuous monitoring of components with complex geometries and provides extensive information about their structural integrity and their overall condition. Composite overwrapped pressure vessels (COPVs) used for storing hydrogen gases at very high pressures are an example of a critical infrastructure that could benefit significantly from SHM. This can be used to increase the periodic inspection intervals, ensure safe operating conditions by early detection of anomalies, and ultimately estimate the remaining lifetime of COPVs. Therefore, in the digital quality infrastructure initiative (QI-Digital) in Germany, an SHM system is being developed for COPVs used in a hydrogen refueling station. In this study, the results of a lifetime fatigue test on a Type IV COPV subjected to many thousands of load cycles under different temperatures and pressures are presented to demonstrate the strengths and challenges associated with such an SHM system. During the cyclic testing up to the final material failure of the COPV, a sensor network of fifteen surface-mounted piezoelectric (PZT) wafers was used to collect the UGW data. However, the pressure variations, the aging process of the COPV, the environmental parameters, and possible damages simultaneously have an impact on the recorded signals. This issue and the lack of labeled data make signal processing and analysis even more demanding. Thus, in this study, semi-supervised, and unsupervised deep learning approaches are utilized to separate the influence of different variables on the UGW data with the final aim of detecting and localizing the damage before critical failure. T2 - 11th European Workshop on Structural Health Monitoring CY - Potsdam, Germany DA - 10.06.2024 KW - Anomaly detection KW - Damage localization KW - Deep learning KW - Structural health monitoring KW - Ultrasonic-guided waves PY - 2024 AN - OPUS4-60745 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - El Moutaouakil, H. A1 - Fuchs, C. A1 - Savli, E. A1 - Heimann, Jan A1 - Prager, Jens A1 - Moll, J. A1 - Tschöke, K. A1 - Márquez Reyes, O. A1 - Schackmann, O. A1 - Memmolo, V. A1 - Schneider, T. T1 - Acquiring a Machine Learning Data Set for Structural Health Monitoring of Hydrogen Pressure Vessels at Operating Conditions using Guided Ultrasonic Waves N2 - Hydrogen is an energy source of increasing importance. As hydrogen is very reactive to air and needs to be stored under high pressure, it is crucial to provide safe transportation and storage. Therefore, structural health monitoring, based on guided ultrasonic waves and machine learning methods, is used for Composite Overwrapped Pressure Vessels (COPVs) containing hydrogen. To acquire data that allows robust detection of COPV defects, there are two main process parameters to consider. These are the pressurization of the vessel and the temperature conditions at the vessel. This paper will focus on the derivation of a design of experiment (DoE) from the needs of various validation scenarios (e.g. concerning pressure, temperature or excitation frequency). Practical limitations must be considered as well. We designed experiments with multiple reversible damages at different positions. A network of 25 transducers, structured as five rings with five sensors in one line, is installed on a vessel. Guided ultrasonic waves are used via the pitch-catch procedure, which means that the transducers act pairwise as transmitter and receiver in order to measure all transmitterreceiver combinations. This leads to 600 signal paths, recorded by a Verasonics Vantage 64 LF data acquisition system. Finally, the influences of temperature and pressure within the acquired data set are going to be visualized. T2 - 11th European Workshop on Structural Health Monitoring CY - Potsdam, Germany DA - 10.06.2024 KW - Composite Overwrapped Pressure Vessel KW - Hydrogen KW - Guided Ultrasonic Waves KW - Data Acquisition KW - Pressurization KW - Machine Learning PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607472 DO - https://doi.org/10.58286/29754 SN - 1435-4934 SP - 1 EP - 8 AN - OPUS4-60747 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - PREDIS The pre-disposal management of radioactive waste N2 - This presentation summarizes the opbjectives and the progress of the EURATOM project PREDIS (pre-disposal management of radioactive waste) and its workpackage 7 in particular. Focus is on the development of wireless sensors for monitoring radioactive waste packages, measuring radiation, temperature, pressure and humidity. T2 - DigiDecom 2022 CY - Halden, Norway DA - 18.10.2022 KW - Radioactive waste KW - Monitoring KW - Wireless KW - RFID PY - 2022 AN - OPUS4-56321 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chaudhuri, Somsubhro A1 - Stamm, Michael A1 - Lapšanská, Ivana A1 - Lançon, Thibault A1 - Osterbrink, Lars A1 - Driebe, Thomas A1 - Hein, Daniel A1 - Harendt, René T1 - Infrared Thermography of Turbulence Patterns of Operational Wind Turbine Rotor Blades Supported With High‐Resolution Photography: KI‐VISIR Dataset N2 - With increasing wind energy capacity and installation of wind turbines, new inspection techniques are being explored to examine wind turbine rotor blades, especially during operation. A common result of surface damage phenomena (such as leading edge erosion) is the premature transition of laminar to turbulent flow on the surface of rotor blades. In the KI-VISIR (Künstliche Intelligenz Visuell und Infrarot Thermografie—Artificial Intelligence-Visual and Infrared Thermography) project, infrared thermography is used as an inspection tool to capture so-called thermal turbulence patterns (TTPs) that result from such surface contamination or damage. To complement the thermographic inspections, high-resolution photography is performed to visualise, in detail, the sites where these turbulence patterns initiate. A convolutional neural network (CNN) was developed and used to detect and localise turbulence patterns. A unique dataset combining the thermograms and visual images of operational wind turbine rotor blades has been provided, along with the simplified annotations for the turbulence patterns. Additional tools are available to allow users to use the data requiring only basic Python programming skills. KW - Thermography KW - Thermografie KW - Wind energy KW - Leading edge erosion KW - KI PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-615772 DO - https://doi.org/10.1002/we.2958 IS - e2958 SP - 1 EP - 9 PB - Wiley AN - OPUS4-61577 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hicke, Konstantin T1 - Fibre Optic Sensors (Division 8.6) N2 - Fiber optic sensing technology being researched and developed at BAM and its numerous applications/ use cases is presented briefly after a short introductory part on the fundamentals of (distributed) fiber optic sensing. T2 - BAM - RCNDE (UK) Webinar CY - Online meeting DA - 13.11.2024 KW - Distributed fiber optic sensing KW - Structural health monitoring KW - Condition monitoring KW - DAS KW - Embedded fiber optic sensors PY - 2024 AN - OPUS4-61643 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kowalski, Kurt A1 - Hulshoff, S.J. A1 - Ströer, P. A1 - Withag, J. A1 - Genot, A. A1 - Morgans, A.S. A1 - Bake, Friedrich A1 - Venner, K. A1 - Sanders, M.P.J. A1 - Hirschberg, Lionel T1 - Entropy-patch choked-nozzle interaction: quasi-steady-modeling-regime limits probed N2 - Indirect combustion noise due to the interaction of flow inhomogeneities with a choked combustion-chamber exit is an important cause of combustion instability in solid rocket motors. Moreover, it is believed to be an issue in electrical-power generation turbines and aero-engines. If these flow inhomogeneities are essentially characterized by the fluid having a locally appreciablydifferent thermodynamic state, the acoustic response engendered by its interaction with the combustion-chamber exit is commonly referred to as entropy noise. In this paper, dedicated numerical-simulation results of entropy-patch choked-nozzle interactions are presented. Two types of entropy patches were considered: rectangular slugs and circular spots. Moreover, analytical-model-based analysis, of said simulation results, is presented. Based on said analysis, the authors posit the existence of three modeling regimes: the quasi-steady-modeling regime, the blended-physical-effects regime, and the inertial-modeling regime. T2 - 30th AIAA/CEAS Aeroacoustics Conference (2024) CY - Rome, Italy DA - 04.06.2024 KW - Entropy-Nozzle Interaction KW - Indirect Combustion Noise KW - Entropy Noise PY - 2024 SN - 978-1-62410-720-7 DO - https://doi.org/10.2514/6.2024-3113 SP - 1 EP - 23 AN - OPUS4-60174 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lu, Xin A1 - Hicke, Konstantin A1 - Krebber, Katerina T1 - Distributed fiber optic sensing for monitoring of underground facilities N2 - Distributed fiber optic sensing (DFOS) technique is a promising and robust non-destructive testing tool that can seamlessly acquire environmental conditions over large scales. Therefore, it has found extensive applications in structural health monitoring. Its appeal for monitoring underground facilities lies in the intrinsic properties of the optical fiber, such as immunity to magnetic interference, small size, chemical inertia, etc. This paper provides a concise overview of DFOS applications in underground facility monitoring. Following a brief introduction to the workingbnprinciple of the DFOS technique, various examples are provided to demonstrate how distributed fiber sensors contribute to monitoring underground facilities. The paper presents unpublished field test results with an emphasis in the energy sector, including monitoring gas storage facilities, geothermal reservoir exploration, and ground movement detection. Furthermore, the paper identifies several directions for enhancing the DFOS system. T2 - SPIE Photonics Europe CY - Strasbourg, France DA - 07.04.2024 KW - Structure health monitoring KW - Geothermal borehole KW - Distributed fiber optic sensing KW - Ground movement KW - Leakage detection PY - 2024 DO - https://doi.org/10.1117/12.3023571 SN - 0277-786X VL - 13001 SP - 1 EP - 10 PB - SPIE AN - OPUS4-60384 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Barretto, T. A1 - Gentes, S. A1 - Braun, J. A1 - Averin, Anton A1 - Lecompagnon, Julien A1 - Stroncik, N. T1 - Automated non-destructive internal corrosion detection on radioactive drums (ZIKA) N2 - The aim of the ZIKA research project, funded by the BMBF funding program FORKA (FKZ:15S9446 A-C), is the automated detection of internal corrosion of radioactive drums using non-destructive testing (NDT). The newly gained findings will be combined with research results from the previous project EMOS (FKZ:15S9420), which dealt with the external damage of drums. Using NDT, internal corrosion and possible internal sources of damage can be identified before they become a safety-relevant issue. However, if internally sourced damages can be seen externally, the integrity of the damaged drum is no longer guaranteed, which has significant consequences. Therefore, early detection before integrity failure is of particular importance for interim storage facilities with low- and medium-level radioactive waste drums. T2 - Kerntechnik 2024 CY - Leipzig, Germany DA - 11.06.2024 KW - Corrosion detection KW - Non-destructive testing KW - Automated inspection system PY - 2024 SP - 1 EP - 5 AN - OPUS4-60322 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Saeed, Hasan A1 - Chaudhuri, Somsubhro A1 - De Waele, Wim T1 - Experimental evaluation of the short and long fatigue crack growth rate of S355 structural steel offshore monopile weldments in air and synthetic seawater N2 - Welded steel structures used in the offshore wind industry are exposed to harsh marine environments, which can result in corrosion-induced fatigue damage. Of particular concern is the heat affected zone (HAZ) of welded joints, a region known for its altered microstructure and mechanical properties, which can significantly influence the initiation and propagation of fatigue cracks. This study investigates the short and long fatigue crack growth rates, and the effect of seawater exposure, for the HAZ in S355 steel weldments. Single-edge notch bend (SENB) specimens are used, with a shallow notch in the HAZ. A series of specimens is immersed in synthetic seawater that is continuously circulated at a controlled temperature to assess the synergistic effects of corrosion and fatigue. The experimental method integrates a novel application of front face strain compliance for monitoring short cracks, alongside an extended back-face strain compliance approach for monitoring long crack propagation. It is concluded that the short fatigue crack growth rate of the HAZ is 2.7 to 3.5 times higher in seawater as compared to air. As the crack propagates and enters into the long crack regime, the ratio decreases to 2.2 times at the transition point of the two-stage crack growth curve and further decreases to 1.5 times when the notch advances towards fracture. The findings indicate that the fatigue crack growth rates documented in standards tend to be on the conservative side. This study significantly enriches the fatigue crack growth data available in literature, which will contribute to a more accurate lifetime assessment offshore wind turbine structures. KW - Fatigue crack growth rate KW - Short crack KW - Offshore monopile foundation KW - Corrosion fatigue PY - 2024 DO - https://doi.org/10.1016/j.apor.2024.104063 VL - 149 SP - 1 EP - 17 PB - Elsevier Ltd. AN - OPUS4-60691 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mehri Sofiani, F. A1 - Tacq, J. A1 - Elahi, S.A. A1 - Chaudhuri, Somsubhro A1 - De Waele, W. T1 - A hybrid probabilistic-deterministic framework for prediction of characteristic size of corrosion pits in low-carbon steel following long-term seawater exposure N2 - A hybrid deterministic-probabilistic framework is presented that combines in-situ measurements and numerical analysis to predict the characteristic size of corrosion pits over extended periods of exposure to seawater. A probabilistic model, informed by corrosion current density and temperature data, applies a sampling method to a range of overpotential values to reflect the surface deterioration in terms of pitting. The model is calibrated and validated with pit size data obtained from corroded coupons. Results reveal a positively skewed truncated lognormal distribution of pit depths which implies a higher prevalence of smaller pit depths, corroborated both experimentally and numerically. KW - Pitting corrosion KW - Offshore structures KW - Probabilistic analysis KW - Potentiodynamic polarisation PY - 2024 DO - https://doi.org/10.1016/j.corsci.2024.112039 VL - 232 SP - 1 EP - 15 PB - Elsevier Ltd. AN - OPUS4-60693 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Chaudhuri, Somsubhro T1 - Passive infrared thermography as an inspection tool for operational wind turbine rotor blades N2 - The growing wind energy infrastructure presents a significant challenge in the maintenance and operation of wind turbines (WT) and their intricate components. An important aspect of WT maintenance is the inspection of wind turbine rotor blades (WTB) to ensure the overall health and safety of the turbine. This inspection process involves both visual and mechanical examinations of the blades to identify any indicators of damage or wear that could compromise their performance and, consequently, the structural integrity of the entire WT system. The complexity of WTBs is compounded by their ever-expanding dimensions, exceeding 100 meters in length for 16 MW WT systems, and their multi-material composition. Within this context, passive infrared thermography emerges as a potential alternative to conventional contact- or proximity-based inspection methods. Unlike active thermography, passive thermography uses solar radiation and ambient temperature variation for thermal contrast, eliminating the need for traditional heat lamps, flash, or laser-based techniques. A novel inspection method has been developed to semi-autonomously assess wind turbine blades (WTBs) while the wind turbine (WT) is operational, from ground level. This approach leverages optimal thermal contrast, which depends on prevailing weather conditions during field measurements, enabling the visualization of both external and internal features of the WTBs through post-processing techniques. In this study, thermal data obtained through passive thermography is compared with contemporaneous visual imagery to definitively classify observed features in thermal images as either surface or sub-surface features. This analysis, coupled with corresponding weather conditions, provides valuable insights into the capabilities and limitations of the inspection technique. Additionally, finite-element-based (FE) thermal simulations of a WTB section are employed to parametrically assess the influence of weather conditions, beyond those observed during field measurements, based on a validated model. In addition, the thermal images also consist of thermal signatures of leading-edge turbulence due to possible leading-edge erosion in WTBs. These are primarily vortices, and their shape and size depend on the morphology of the damage as well as the rotational speed of the WTBs. The inspections are accompanied by automatic data evaluation of the thermal signatures. To improve the precision of erosion damage identification, a fully convolutional network (FCN) is employed, trained, and tested using over 1000 annotated thermographic blade images. Additionally, the study introduces strategies for grouping smaller damage indications and simplification rules based on realistic thermal imaging resolutions. As leading-edge erosion could potentially lead to annual energy production (AEP) losses, this technique could prove to be a powerful tool in establishing the presence of damage and the resulting AEP loss. T2 - 20th World Conference on Non-Destructive Testing CY - Incheon, South Korea DA - 27.05.2024 KW - Non-destructive testing KW - Thermografie KW - Wind turbine rotor blades KW - Windenergie Anlage Rotorblätter KW - Thermography PY - 2024 AN - OPUS4-60695 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Eisermann, R. A1 - Esterl, F. A1 - Schuchardt, M. A1 - Breithaupt, Mathias A1 - Plath, R. T1 - Distributed acoustic/vibration sensing: Towards advanced transformer condition monitoring N2 - A novel method for transformer vibration monitoring using intensity-based distributed acoustic/vibration sensing (DAS/DVS) is presented. Fibre optic sensors were fully integrated into an oil-filled medium voltage distribution transformer. Opencircuit in-situ measurements were carried out using a single and three-phase supply with an electrical power of up to 30 kVA. Spectral analysis of the mechanical vibrations were performed by measuring the frequency response of the transformer using plain fibre- and transducer-based DVS approaches. The results were compared with the spectra of a microphone mounted on the outside of the transformer housing and the electrical measurements on the high voltage side. Using the fibre optic DVS based monitoring we were able to detect changes in operating power and frequency. Further it could be shown, that it is possible to identify anomalous behaviour such as electrical/mechanical noise sources using the determined vibration spectra. T2 - 2024 IEEE International Conference on High Voltage Engineering and Applications (ICHVE) CY - Berlin, Germany DA - 18.08.2024 KW - Distributed acoustic sensing KW - DAS KW - Transformer monitoring PY - 2024 DO - https://doi.org/10.1109/ICHVE61955.2024.10676084 SP - 1 EP - 4 PB - IEEE CY - New York City, New York, USA AN - OPUS4-61798 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Krankenhagen, Rainer A1 - Chaudhuri, Somsubhro A1 - Stamm, Michael A1 - Lapšanská, Ivana A1 - Aderhold, J. A1 - Schlüter, F. T1 - EvalTherm – Evaluierung der passiven Thermografie für die Zustandsbewertung von Rotorblättern an Windenergieanlagen N2 - Der Bericht gibt einen Überblick über im Rahmen des Projektes durchgeführte Forschungsarbeiten sowie ausgewählte Ergebnisse. Er wurde zusammen mit dem FhI für Holzforschung (WKI) erstellt. KW - Rotorblattinspektion KW - Passive Thermografie KW - Feldmessungen KW - Windturbine PY - 2025 N1 - Schlussbericht des Projektes N1 - Laufzeit: 1.9.2020 – 31.8.2024 N1 - Das Verbundprojekt wurde im Rahmen des 7. Energieforschungsprogramms "Innovationen für die Energiewende" gefördert N1 - Das Vorhaben wurde mit Mitteln des Bundesministeriums für Wirtschaft und Klima unter dem Förderkennzeichen 03EE3035A/B gefördert SP - 1 EP - 67 PB - Technische Informationsbibliothek (TIB) CY - Hannover AN - OPUS4-62647 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Chaudhuri, Somsubhro A1 - Junker, Birgit T1 - Infrared thermography as an inspection tool for wind turbine rotor blades N2 - With the rapid expansion of wind turbine construction, rotor blades have increasingly been identified as a primary cause of turbine downtime and failure. This has led to a growing demand for inspection technologies through which energy production losses can be minimised—particularly in comparison to conventional methods such as rope-access inspections—and through which sub-surface blade conditions can be assessed to detect damage or failure in advance. Infrared thermography has been considered as a promising non-contact, full-field inspection method that can be applied to rotor blades in both operational and idle states. In this presentation, delivered at BladesEurope 2025, the physical mechanisms that give rise to thermal contrast during thermographic inspection were explained, as this contrast enables the detection and visualisation of structural features. Results obtained from a collaborative project between BAM and Statkraft Norway were presented, followed by the validation of a finite element simulation through experiments conducted in a climate chamber.” T2 - BladesEurope Forum 2025 CY - Edinburgh, Scotland DA - 29.04.2025 KW - Thermography KW - Wind energy KW - Inspection KW - Windenergie anlage rotorblätte KW - Damage detection PY - 2025 AN - OPUS4-63060 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stamm, Michael A1 - Sridaran Venkat, Ramanan T1 - Harnessing the power of thermal imagery and visual inspection- a mean for reliable damage detection of wind turbine rotor blades N2 - Generation of green electricity as part of the energy transition is leading to a growing market in the wind energy sector all over the world. Maintenance and inspection are key to the reliability, safety and efficiency of wind turbines, the regular maintenance of rotor blades focuses on damage such as erosion on the leading edge of the profile, delamination and thermal cracks due to lightning strikes. To date, visual inspection by technicians (climbers) has been the state of the art and it is time consuming besides posing safety risk for themselves. Recently, drone-based inspections using visual cameras have become more common, enabling fast, reliable and cost-effective inspections. However, no internal damage to the rotor blades can be detected during such an inspection. Thermography is a recognised method for detecting damage beneath the surface of an object, which has been promoted and further developed at BAM for years. To enhance the accuracy and reliability of wind turbine blade inspection, the fusion o T2 - 11th European Workshop on Structural Health Monitoring CY - Potsdam, Germany DA - 10.06.2024 KW - Wind rotor blade inspection KW - Thermography KW - Data fusion KW - Drone inspection KW - Multi-sensors PY - 2024 AN - OPUS4-62515 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stamm, Michael T1 - AI-Assisted thermographic and visual classification of leading-edge erosion of wind turbine blades N2 - The wind industry is crucial for carbon neutrality, with turbines featuring blades over 100 meters long. Regular inspections, often manual and visual, struggle to capture subsurface damage or airflow dynamics. Leading-edge erosion, caused by rain and hail, significantly reduces turbine efficiency. The Federal Institute for Materials Research and Testing (BAM) in Berlin is working with industry partners to classify leading-edge damage and estimate yield loss using ground-based thermographic images. These images visualize airflow disruptions caused by erosion. AI models, trained on 1500 thermographic images, can detect and classify this damage. BAM aims to create a reference dataset by 2024, using data from 30 wind turbines. This dataset will include simultaneous thermographic and high-resolution visual images. The project also explores predicting stall and calculating performance loss due to erosion. A secure data platform facilitates data exchange and federated learning, enhancing AI systems with diverse data. KW - NDT KW - Thermography KW - Wind Turbine Blades KW - AI KW - KI-VISIR PY - 2024 UR - https://source.asnt.org/226h005/ SN - 0025-5327 VL - 82 IS - 6 SP - 14 EP - 15 AN - OPUS4-62452 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Strangfeld, Christoph A1 - Müller-Vahl, H. F. A1 - Nayeri, C. N. A1 - Paschereit, C. O. A1 - Greenblatt, D. T1 - Airfoil synchronous surging and pitching N2 - Combined surging and pitching of an airfoil at the identical frequency (i.e. synchronously), at four different phase differences, was investigated theoretically and experimentally. The most general unsteady theoretical formulation was adopted to calculate the lift coefficient, and then extended to explicitly compute the unsteady bound vortex sheet. This was used for comparison with experiments and facilitated the computation of both Joukowsky and impulsive-pressure lift contributions. Experiments were performed using a symmetric 18 % thick airfoil in an unsteady wind tunnel at an average Reynolds number of 3.0*10^5 , with a free-stream oscillation amplitude of 51 %, an angle-of-attack range of 2° +- 2° and a reduced frequency of 0.097. In general, excellent correspondence was observed between theory and experiment, representing the first direct experimental validation of the general theory. It was shown, both theoretically and experimentally, that the lift coefficient was not accurately represented by independent superposition of surging and pitching effects, due to variations in the instantaneous effective reduced frequency not accounted for during pure pitching. Deviations from theory, observed at angle-of-attack phase leads of 90° and 180°, were attributed to bursting of separation bubbles during the early stages of the acceleration phase. The largest deviations occurred when the impulsive-pressure lift contribution was small relative to the Joukowsky contribution, because the latter was most affected by bubble bursting. Bubble bursting resulted in large form-drag oscillations that occurred at identical phase angles within the oscillation cycle, irrespective of the phase difference between surging and pitching, as well as in the absence of pitching. KW - Unsteady aerodynamics KW - Dynamic stall KW - Separation bubble KW - Bubble bursting PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-630068 DO - https://doi.org/10.1017/jfm.2025.220 SN - 1469-7645 VL - 1009 SP - 1 EP - 33 PB - Cambridge University Press (CUP) AN - OPUS4-63006 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Brunner, Nanine T1 - Digital Certificates: Enabling Automation in Quality Assurance and Metrological Traceability N2 - This presentation describes how the Digital Calibration Certificate (DCC) for temperature was implemented in the accredited calibration laboratory at BAM. It includes an overview of the integration of the digital calibration symbol (digital seal) to ensure authenticity, integrity, and traceability of the certificate. The DCC is provided in a structured XML format, enabling machine-readability and seamless data integration into digital processes. A demonstrator developed within the QI-Digital project is presented to showcase the practical advantages of the DCC over traditional paper or PDF-based certificates — including automation, data security, and improved usability in digital quality infrastructure systems. T2 - Sensor and Measurement Science International (SMSI) CY - Nuremberg, Germany DA - 05.05.2025 KW - DCC KW - QI Digital KW - Demonstrator KW - SMSI in Nürnberg 2025 PY - 2025 AN - OPUS4-63100 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nerger, Deborah T1 - Impact damage characterization at RC plates with planar tomography and FEM N2 - Prediction of dynamic effects of reinforced concrete structures under impact loading is a technical challenge. This is a consequence of the great variability of the physical properties resulting from the wide adaptability of reinforced concrete and a consequence of the wide range of impact loading. Experiments and numerical investigations are normally used on a small scale to address the problem. In this paper, impact tests on reinforced conrete plates with the lateral dimensions of 1.5 m x 1.5 m and a thickness of 30 cm are presented. In bending reinforcement, besides the velocity two properties are varied, the diameter and the spatial distribution of the rebars. Experiments are performed at the Otto-Mohr-Laboratory of the Institute of Concrete Structures of the Technische Universit¨at Dresden. Due to the accelerated fall of the impactor the velocity ranges between 20 and 70 m/s. In addition to the measured quantities such as bearing forces, accelerations are also measured at 4 different positions on and under the plate, as well as the deflection at several positions. The measured data are used for the analysis of the damage form and the numerical examinations with the program Ansys Autodyn and the material model after Drucker-Prager. Numerical investigations support the tests, with detailed analysis of individual effects. These numerical computations and the planar tomographic investigations were carried out at BAM in Berlin. With the help of planar tomographic evaluation, the damaged structure is made visible and compared with the numerical results. Influences of the bending reinforcement are explained on the basis of damage evaluation in the local area and on selected measured values. In addition to the test evaluation, the tomographic and numerical methods are presented. T2 - XI International Conference on Structural Dynamics (EURODYN 2020) CY - Online meeting DA - 23.11.2020 KW - Post-impact evaluation KW - Damage characterization KW - Planar tomography KW - Drucker-Prager KW - Ansys Autodyn PY - 2020 AN - OPUS4-51768 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hicke, Konstantin T1 - KI, Machine Learning und faseroptische Sensorik N2 - Die Verwendung von Methoden des Maschinellen Lernens (ML) und der Künstlichen Intelligenz (KI) im Fachbereich 8.6 Faseroptische Sensorik wird dargestellt. Die vielfältigen Möglichkeiten, Machine Learning auf Basis Künstlicher Neuronaler Netze (ANN) für eine schnelle und effiziente Datenverarbeitung eizusetzen werden demonstriert. Hierfür werden Beispiele für die Anwendungszwecke Messgrößenberechnung, Entrauschen, Interpolation, Bildverarbeitung und Messdatenauswertung aufgezeigt. T2 - Foresight Prozess AM, AP 4, Workshop „In Situ Sensorik“ CY - Online-Meeting DA - 09.11.2020 KW - Verteilte faseroptische Sensorik KW - KI KW - Künstliche Intelligenz KW - Machine Learning KW - Künstliche Neuronale Netze PY - 2020 AN - OPUS4-51545 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Thiele, Marc T1 - Detection and monitoring of the fatigue crack growth on welds – Application-oriented use of NDT methods N2 - Early detection of fatigue cracks and accurate measurements of the crack growth play an important role in the maintenance and repair strategies of steel structures exposed to cyclic loads during their service life. Observation of welded connections is especially of high relevance due to their higher susceptibility to fatigue damage. The aim of this contribution was to monitor fatigue crack growth in thick welded specimens during fatigue tests as holistically as possible, by implementing multiple NDT methods simultaneously in order to record the crack initiation and propagation until the final fracture. In addition to well-known methods such as strain gauges, thermography, and ultrasound, the crack luminescence method developed at the Bundesanstalt für Materialforschung und -prüfung (BAM), which makes cracks on the surface particularly visible, was also used. For data acquisition, a first data fusion concept was developed and applied in order to synchronize the data of the different methods and to evaluate them to a large extent automatically. The resulting database can ultimately also be used to access, view, and analyze the experimental data for various NDT methods. During the conducted fatigue tests, the simultaneous measurements of the same cracking process enabled a comprehensive comparison of the methods, highlighting their individual strengths and limitations. More importantly, they showed how a synergetic combination of different NDT methods can be beneficial for implementation in large-scale fatigue testing but also in monitoring and inspection programs of in-service structures - such as the support structures of offshore wind turbines. T2 - Fatigue Design 2023 CY - Senlis, France DA - 29.11.2023 KW - Crack growth KW - Fatigue KW - NDT KW - Welded PY - 2023 AN - OPUS4-62374 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heimann, Jan T1 - How structural health monitoring can be embedded in a digital quality infrastructure: an example. N2 - The digital Quality Infrastructure (QI) initiative “QI-Digital” in Germany is focusing on implementing new technologies and approaches to ensure that the task of quality assurance is more efficient and ready for the digital and green transformation of the economy. The implementation of quality control key elements, such as Smart Standards, Digital Certificates and QI-cloud solutions shall contribute to solving the socio-economic, ecological, and technological challenges of our time. Hydrogen is a key energy carrier and has the potential to play a significant role in the energy transition, especially in mobility. An essential factor for the broad acceptance of hydrogen-based mobility is the availability of refueling stations that operate reliably and safely. Using the example of a Hydrogen Refueling Station (HRS) built within the QI-Digital initiative, the Federal Institute for Material Research and Testing (BAM) aims to establish a real laboratory where modern measurement techniques and new digital methods are implemented to enhance operational safety, availability, and economic efficiency and render the technology more attractive for the industry. In this work, we present an approach to establish a Structural Health Monitoring (SHM) system on a high-pressure buffer inside HRS and show how it could be embedded into a digital QI. The high-pressure buffers are essential components of the plant which are currently inspected periodically without regard to their operating history. Focusing on the transition to a continuous and digitally supported monitoring of the component’s integrity during operation the novel inspection scheme will be linked to a completely digitalized component-related documentation and tested using digital certificates. This allows the operational safety and, if necessary, the remaining useful lifetime to be assessed on an ongoing basis and to be a valuable contribution to increasing sustainability. T2 - 11th European Workshop on Structural Health Monitoring CY - Potsdam, Germany DA - 10.06.2024 KW - Digital transformation KW - Industry 4.0 KW - Quality control KW - Quality infrastructure KW - Reliability KW - Structural health monitoring PY - 2024 AN - OPUS4-61484 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Karapanagiotis, Christos A1 - Krebber, Katerina T1 - Machine Learning Approaches in Brillouin Distributed Fiber Optic Sensors N2 - This paper presents reported machine learning approaches in the field of Brillouin distributed fiber optic sensors (DFOSs). The increasing popularity of Brillouin DFOSs stems from their capability to continuously monitor temperature and strain along kilometer-long optical fibers, rendering them attractive for industrial applications, such as the structural health monitoring of large civil infrastructures and pipelines. In recent years, machine learning has been integrated into the Brillouin DFOS signal processing, resulting in fast and enhanced temperature, strain, and humidity measurements without increasing the system’s cost. Machine learning has also contributed to enhanced spatial resolution in Brillouin optical time domain analysis (BOTDA) systems and shorter measurement times in Brillouin optical frequency domain analysis (BOFDA) systems. This paper provides an overview of the applied machine learning methodologies in Brillouin DFOSs, as well as future perspectives in this area. KW - Distributed fiber optic sensors KW - BOTDA KW - BOFDA KW - Machine learning KW - Strain and temperature measurements KW - Artificial neural networks PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-580145 DO - https://doi.org/10.3390/s23136187 VL - 23 IS - 13 SP - 1 EP - 26 PB - MDPI AN - OPUS4-58014 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heimann, Jan A1 - Charmi, Amir A1 - Karapanagiotis, Christos A1 - Hashemi, Seyedreza A1 - Prager, Jens T1 - How structural health monitoring can be embedded in a digital quality infrastructure: an example. N2 - The digital Quality Infrastructure (QI) initiative “QI-Digital” in Germany is focusing on implementing new technologies and approaches to ensure that the task of quality assurance is more efficient and ready for the digital and green transformation of the economy. The implementation of quality control key elements, such as Smart Standards, Digital Certificates and QI-cloud solutions shall contribute to solving the socio-economic, ecological, and technological challenges of our time. Hydrogen is a key energy carrier and has the potential to play a significant role in the energy transition, especially in mobility. An essential factor for the broad acceptance of hydrogen-based mobility is the availability of refueling stations that operate reliably and safely. Using the example of a Hydrogen Refueling Station (HRS) built within the QI-Digital initiative, the Federal Institute for Material Research and Testing (BAM) aims to establish a real laboratory where modern measurement techniques and new digital methods are implemented to enhance operational safety, availability, and economic efficiency and render the technology more attractive for the industry. In this work, we present an approach to establish a Structural Health Monitoring (SHM) system on a high-pressure buffer inside HRS and show how it could be embedded into a digital QI. The high-pressure buffers are essential components of the plant which are currently inspected periodically without regard to their operating history. Focusing on the transition to a continuous and digitally supported monitoring of the component’s integrity during operation the novel inspection scheme will be linked to a completely digitalized component-related documentation and tested using digital certificates. This allows the operational safety and, if necessary, the remaining useful lifetime to be assessed on an ongoing basis and to be a valuable contribution to increasing sustainability. T2 - 11th European Workshop on Structural Health Monitoring CY - Potsdam, Germany DA - 10.06.2024 KW - Structural health monitoring KW - Quality infrastructure KW - Digital transformation KW - Reliability KW - Quality control KW - Industry 4.0 PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607109 DO - https://doi.org/10.58286/29769 SN - 1435-4934 SP - 1 EP - 7 PB - NDT.net AN - OPUS4-60710 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Greenblatt, D. A1 - Müller-Vahl, H. A1 - Strangfeld, Christoph T1 - Laminar separation bubble bursting in a surging stream N2 - The effect of high-amplitude harmonic surging on airfoil laminar separation bubbles, at small angles of attack, was investigated experimentally in a dedicated surging-flow wind tunnel. A generalized pressure coefficient was developed that accounts for local static pressure variations due to surging. This critical generalization facilitated direct comparisons between surging and quasisteady pressure coefficients, and thus unsteady effects could be distinguished from Reynolds number effects. A momentum-integral boundary layer analysis was implemented to determine movement of the bubble separation point, and movement of the transition point was extracted from experimental surface pressure coefficients. The most significant finding was that bubble bursting occurs, counterintuitively, during early imposition of the favorable temporal pressure gradient, because the favorable pressure gradient rapidly drives the bubble aft, rendering it unable to reattach. This surge-induced dynamic stall mechanism resulted in large lift and form-drag coefficient oscillations. Furthermore, failure to implement the generalized pressure coefficient definition resulted in temporal form-drag coefficient errors of up to 400 counts. KW - Aerodynamics KW - Boundary layer receptivity, stability & separation KW - Boundary layers PY - 2023 DO - https://doi.org/10.1103/PhysRevFluids.8.L012102 SN - 2469-990X VL - 8 IS - 1 SP - 1 EP - 11 PB - American Physical Society AN - OPUS4-56860 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ratkovac, Mirjana A1 - Gerards-Wünsche, Paul A1 - Thiele, Marc A1 - Brackrock, Daniel A1 - Stamm, Michael T1 - Detection and monitoring of the fatigue crack growth on welds – Application-oriented use of NDT methods N2 - Early detection of fatigue cracks and accurate measurements of the crack growth play an important role in the maintenance and repair strategies of steel structures exposed to cyclic loads during their service life. Observation of welded connections is especially of high relevance due to their higher susceptibility to fatigue damage. The aim of this contribution was to monitor fatigue crack growth in thick welded specimens during fatigue tests as holistically as possible, by implementing multiple NDT methods simultaneously in order to record the crack initiation and propagation until the final fracture. In addition to well-known methods such as strain gauges, thermography, and ultrasound, the crack luminescence method developed at the Bundesanstalt für Materialforschung und -prüfung (BAM), which makes cracks on the surface particularly visible, was also used. For data acquisition, a first data fusion concept was developed and applied in order to synchronize the data of the different methods and to evaluate them to a large extent automatically. The resulting database can ultimately also be used to access, view, and analyze the experimental data for various NDT methods. During the conducted fatigue tests, the simultaneous measurements of the same cracking process enabled a comprehensive comparison of the methods, highlighting their individual strengths and limitations. More importantly, they showed how a synergetic combination of different NDT methods can be beneficial for implementation in large-scale fatigue testing but also in monitoring and inspection programs of in-service structures - such as the support structures of offshore wind turbines. T2 - Fatigue Design 2023 (FatDes 2023) CY - Senlis, France DA - 29.11.2023 KW - Fatigue KW - Welded KW - NDT KW - Crack growth PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-600238 DO - https://doi.org/10.1016/j.prostr.2024.03.062 VL - 57 SP - 560 EP - 568 PB - Elsevier B.V. AN - OPUS4-60023 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Held, Mathias A1 - Bulling, Jannis A1 - Lugovtsova, Yevgeniya A1 - Prager, Jens T1 - Determination of isotropic elastic constants from dispersion images based on ultrasonic guided waves by using neural networks N2 - This article presents a method to use the dispersive behavior of ultrasonic guided waves and neural networks to determine the isotropic elastic constants of plate-like structures through dispersion images. Therefore, two different architectures are compared: one using convolutions and transfer learning based on the EfficientNetB7 and a Vision Transformer-like approach. To accomplish this, simulated and measured dispersion images are generated, where the first is applied to design, train, and validate and the second to test the neural networks. During the training of the neural networks, distinct data augmentation layers are employed to introduce artifacts appearing in measurement data into the simulated data. The neural networks can extrapolate from simulated to measured data using these layers. The trained neural networks are assessed using dispersion images from seven known material samples. Multiple variations of the measured dispersion images are tested to guarantee the prediction stability. The study demonstrates that neural networks can learn to predict the isotropic elastic constants from measured dispersion images using only simulated dispersion images for training and validation without needing an initial guess or manual feature extraction, independent of the measurement setup. Furthermore, the suitability of the different architectures for generating information from dispersion images in general is discussed. KW - Ultrasonic guided waves KW - Dispersion KW - Elastic constants KW - Neural networks KW - Image processing KW - Vision transformer PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607090 DO - https://doi.org/10.1016/j.ultras.2024.107403 SN - 0041-624X VL - 143 SP - 1 EP - 48 PB - Elsevier B.V. AN - OPUS4-60709 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wu, Cheng-Chieh A1 - Weisbrich, S. A1 - Burger, M. A1 - Neitzel, F. ED - Zemčík, R. T1 - A four-point bending test apparatus for measurement- and model-based structural analysis N2 - By means of a small-scale truss bridge, the ability of the Measurement- and Model-based Structural Analysis to detect and localise damage was examined in. Although there was no noteworthy difficulty in detecting damage, it turned out that damage localisation responds sensitively to systematic influences, i.e. non-modelled properties of the mechanical model. Therefore, another experiment is being conducted to re-examine the Measurement- and Model-based Structural Analysis. For this purpose, the bending test is carried out as it has been already theoretically respectively numerically discussed in. In this attempt, the systematic influences such as residual stress are kept as low as possible. T2 - 36th Danubia Adria Symposium on Advances in Experimental Mechanics CY - Pilsen, Czech Republic DA - 24.09.2019 KW - Damage detection KW - Adjustment calculation KW - Finite element method KW - Integrated analysis PY - 2020 UR - http://www.sciencedirect.com/science/article/pii/S2214785320326432 DO - https://doi.org/10.1016/j.matpr.2020.04.028 SN - 2214-7853 VL - 32 IS - 2 SP - 156 EP - 161 PB - Elsevier Ltd. AN - OPUS4-51551 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Averin, Anton T1 - Automated thermographic inspection of radioactive waste drums N2 - In Germany, more than 130,000 cubic meters of low- and medium-level radioactive waste, comprising approximately 90% of the nation’s total radioactive waste, are stored in 200-liter drums. These waste drums, housed in interim storage facilities, are subject to human visual inspections for outer corrosion, while the final disposal site, the Konrad mine, is scheduled for completion in 2030. Manual inspections introduce the risk of human error, making the process less reliable and less safe. The proposed study aims to automate these inspections by implementing remote and non-destructive testing (NDT) methods. The part of project specifically focuses on the application of infrared thermography to detect inner defects in the metallic drums, which could not have been detected so far using visual inspection alone. However, several challenges affect the accuracy of thermographic inspections, such as the presence of surface contaminants (scratches, dirt, stickers), multiple paint layers with low thermal conductivity, and barrel curvature, which disrupt heat distribution and obscure defect signals. This study explores the effectiveness of various thermographic heat sources—flash lamps and laser—as well as techniques including conventional pulse thermography (PT), lock-in thermography. It explores various thermal data processing methods as principal component thermography (PCT), pulse-phase thermography (PPT) and thermal signal reconstruction (TSR). Additionally, machine learning models were estimated to process thermographic images, effectively filtering artifacts (e.g. surface contaminants). The findings suggest that combining advanced thermography techniques with machine learning improves defect detection, ensuring more reliable and automated inspection processes for radioactive waste storage. T2 - SPIE Defense+Commercial Sensing- Thermosense: Thermal Infrared Applications XLVII CY - Orlando, FL, USA DA - 13.04.2025 KW - Infrared thermography KW - Automated inspection KW - Pulse-phase thermography KW - Principal component thermography KW - Thermal Data Processing KW - Laser thermography KW - Defect detection KW - Machine Learning PY - 2025 AN - OPUS4-63119 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Karapanagiotis, Christos ED - Krebber, Katerina T1 - Machine learning for strain, temperature and humidity discrimination in Brillouin optical frequency domain analysis N2 - We propose to our knowledge for the first time an ensemble of probabilistic machine learning models for strain, temperature and humidity discrimination in Brillouin optical frequency domain analysis (BOFDA) applying a two-fiber configuration. T2 - 28th International Conference on Optical Fiber Sensors CY - Hamamatsu, Japan DA - 20.11.2023 KW - Multiparameter sensing KW - Machine learning KW - Fiber optic sensors KW - Structural health monitoring PY - 2023 SP - 1 EP - 4 PB - Optica Publishing Group AN - OPUS4-59397 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Müller-Vahl, H. F. A1 - Strangfeld, Christoph A1 - Nayeri, C. N. A1 - Paschereit, C. O. A1 - Greenblatt, D. T1 - Dynamic Stall Under Combined Pitching and Surging N2 - Dynamic stall often occurs under conditions of simultaneous unsteady pitching and surging (e.g., rotorcraft and wind turbines), butmanymodels employ a dimensionless time base that implicitly assumes that surging is superimposed, in a quasi-steady manner, on dynamic pitching. An unsteady wind tunnel was used to examine this assumption, where a technique was developed to quantify the unsteady effects of surging on a pitching NACA 0018 airfoil. The technique involved performing multiple harmonic pitching experiments under nominally steady freestream conditions that bracketed a corresponding 50% surging amplitude (1.25 ⋅ 105 ≤ Re ≤ 3.75 ⋅ 105). By interpolating these data, unsteady-pitching/quasi-steady-surging data sets were constructed and compared with de facto synchronous pitch and surging experiments, thereby isolating the unsteady effects of surging on a pitching airfoil. Both large and small poststall maximum angles of attack (αs + 5° and αs + 15°) were considered at multiple pitch-surge phase differences. During deep dynamic stall (αs � 15°), with large-scale separation, surging was seen to have a secondary effect on the unsteady aerodynamics. However, at small poststall maximum angles of attack (αs + 5°), either light or deep dynamic stall behavior was observed depending upon the pitch-surge phase difference. This was attributed to Reynolds number history effects, exemplified by boundary-layer transition, and thus it can be referred to as “transitional” dynamic stall. KW - Dynamic stall KW - Angle of attack oscillations KW - Free stream velocity osciallations PY - 2020 DO - https://doi.org/10.2514/1.J059153 VL - 58 IS - 12 SP - 5134 EP - 5145 PB - American Institute of Aeronautics and Astronautics AN - OPUS4-51037 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nerger, Deborah A1 - Moosavi, Robabeh A1 - Bracklow, F. A1 - Hering, M. A1 - Kühn, T. A1 - Curbach, M. A1 - Hille, Falk A1 - Rogge, Andreas T1 - Planar tomography and numerical analysis for damage characterization of impact loaded RC plates N2 - The damage analysis of reinforced concrete (RC) is of high interest for reasons of effective maintenance and structural safe-ty of buildings. The damage structures of RC plates loaded by an impact were investigated, applying X-ray planar tomogra-phy and finite element method (FEM). Planar tomography allows getting three-dimensional information of the RC elements and the damage including crack, spalling and scabbing. The FEM model validated on the tomography data justifies the appli-cation for further predictions of the damage description. In this study, we investigated concrete plates of three different thick-ness subjected to impacts at different low- and medium-velocity, whereby the used impactor had a flat tip, which resulted in small penetrations on the front side and scabbing on the rear side. In order to quantify the damage, the damage volume and its distribution through the plate were computed and the correlations between degree of damage and impact velocity were found out. KW - Impact KW - Damage characterization KW - Planar tomography KW - Numeric simulation KW - Reinforced concrete structure PY - 2020 DO - https://doi.org/10.1002/cend.202000017 VL - 8 SP - 1 EP - 19 PB - Wiley AN - OPUS4-51117 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nerger, Deborah A1 - Hille, Falk A1 - Moosavi, Robabeh A1 - Grunwald, Marcel A1 - Redmer, Bernhard A1 - Kühn, T. A1 - Hering, M. A1 - Bracklow, F. T1 - Post-impact evaluation at RC plates with planar tomography and FEM N2 - Due to the wide range of applications, the easy production and the large field of use, reinforced concrete (RC) is a widespread building material. This variety of applications is reflected in a wide range of physical material properties. Not only therefor it still is a technical challenge to provide all necessary test conditions for experimentally reproducing dynamic effects under impact loading of RC structures. In this paper we present investigations on the thicknesses of RC plates under low and medium high velocity impact loading by a flat-tipped impactor. The planar tomography setup at BAM is used to visualize the impact damage and to characterize the damage features such as cracks, scabbing and spalling. Further, the comparison of tomography results with those of an applied numeric simulation analysis is used to verify the numeric models for future damage prognosis under impact loading. Using the results of both, the tomographic as well as the FE analysis, different damage features were investigated and compared regarding their validity. Crack damage plays a leading part and the significance of summarized crack values as well as their distribution is analyzed. The total damage value but also the determined damage distribution both provide an input for describing damage as a function of the impactor velocity and plate thickness. KW - Reinforced concrete structure KW - Post-impact evaluation KW - Damage characterization KW - Ansys Autodyn KW - Drucker-Prager KW - Planar tomography PY - 2020 DO - https://doi.org/10.1016/j.matpr.2020.05.671 SP - 1 EP - 10 PB - Elsevier AN - OPUS4-51115 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kruschwitz, Sabine A1 - Munsch, Sarah Mandy T1 - Potential automatisierter NMR-Messungen zur Ermittlung von Hydratationseigenschaften - ein Vergleich mit Vicat- und Wärmeflusskalorimetrie-Ergebnissen N2 - Es werden Ergebnisse von 1H-NMR-Relaxometrie-Messungen an Salzbeton und einem alkali-aktivierten Material, die im Rahmen des Themenfeldprojektes Seal Waste Safe durchgeführt werden, vorgestellt. Dabei wird die zeitliche Entwicklung von ausgewählten Merkmalen der ermittelten T2-Relaxationszeitenverteilungen während der Hydratation betrachtet. Als Referenz zur Identifikation von charakteristischen Hydratationsereignissen dienen der Vicat-Nadeleindringversuch und Wärmeflusskalorimetrie. T2 - Online-Workshop „Dauerhafte Verschlussbauwerke für Endlager“ CY - Online meeting DA - 14.02.2022 KW - NMR-Relaxometrie KW - Alkali-aktiviertes Material KW - Salzbeton KW - Seal Waste Safe PY - 2022 AN - OPUS4-54945 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schröder, Nina T1 - Local strain behaviour by digital image correlation of cross weld tensile specimens of high strength steel with two different Ti microalloying routes N2 - Microalloying elements such as Nb and Ti play a decisive function in achieving the desired mechanical strength of quenched and tempered, high-strength fine-grain structural steels with a nominal yield strength ≥ 690 MPa. The current specifications for the chemical composition only provide manufacturers with upper limits. However, even minor deviations in the alloy concept can have a significant impact on the mechanical properties. Consequently, accurate prediction of weldability and the integrity of welded joints becomes difficult or even impossible due to differences in composition and the resulting microstructures. Undesirable consequences include a possible softening of the heat-affected zone (HAZ) or, conversely, hardening effects. In view of these challenges, various microalloying strategies with different Ti and Nb contents are being systematically investigated for the first time using specially developed laboratory casting alloys. Each alloying route is based on the common S690QL, maintaining both the chemical composition and the heat treatment parameters. To analyse the weldability, three-layer welds were performed using gas metal arc welding (GMAW) and critical microstructures, such as areas of the heat-affected zone (HAZ) that exhibit significant softening or hardening, were identified. The effect of the softened HAZ region on failure was evaluated using transverse tensile specimens. Digital image correlation (DIC) is used to image changes in local strains in different HAZ regions in situ. Using a specially developed mirror system, the local strains of the microstructure zones on the top and bottom of the weld are recorded simultaneously. This makes it possible to analyse how the weld seam geometry (e.g., V-seam) influences the strain gradients. In addition, the analysis of the local deformation helps to understand the effects of the softened HAZ on the global strain, the fracture constriction, the fracture position, and the overall fracture behavior T2 - The 77th IIW Annual Assembly and International Conference on Welding and Joining CY - Rhodos, Greece DA - 07.07.2024 KW - HSLA KW - Digital Image Correlation KW - Microalloy KW - GMAW KW - HAZ KW - Cross-weld tensile test PY - 2024 AN - OPUS4-60794 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Karapanagiotis, Christos A1 - Schukar, Marcus A1 - Krebber, Katerina T1 - Verteilte faseroptische Sensoren zur Zustandsüberwachung von Verbundwerkstoff-Druckbehältern T1 - Distributed fiber optic sensors for structural health monitoring of composite pressure vessels N2 - In diesem Beitrag geben wir einen umfassenden Überblick über unsere Forschung auf dem Gebiet der verteilten faseroptischen Sensorik für die strukturelle Zustandsüberwachung von Wasserstoffdruckbehältern aus Verbundwerkstoffen. Insbesondere zeigen wir, wie die Integration von faseroptischen Sensoren in Druckbehälter aus Verbundwerkstoffen die Sicherheit erhöht und gleichzeitig die Wartungskosten senkt. Die geringe Größe von Lichtwellenleitern ermöglicht ihre Integration in Verbundwerkstoffstrukturen während des Herstellungsprozesses, wodurch eine kontinuierliche Überwachung sowie eine präzise Erkennung und Lokalisierung von Strukturschäden während des Betriebs der Druckbehälter ermöglicht wird. Wir erörtern auch das Potenzial modernster Signalverarbeitungsmethoden und des maschinellen Lernens für die Weiterentwicklung der vorausschauenden Instandhaltung. Die von uns vorgestellten Anwendungen von faseroptischen Sensoren zeigen, dass sie einen wichtigen Beitrag zur Energiewende hin zu erneuerbaren Energien leisten können. KW - Verteilte faseroptische Sensoren KW - Verbundwerkstoffe KW - Wasserstoff-Druckbehälter KW - Strukturüberwachung KW - Maschinelles Lernen PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-596290 DO - https://doi.org/10.1515/teme-2023-0170 SN - 0171-8096 SP - 1 EP - 12 AN - OPUS4-59629 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Karapanagiotis, Christos T1 - Towards predictive maintenance of hydrogen pressure vessels based on multi-sensor data fusion and digital twin modeling N2 - Hydrogen pressure vessels are among the most essential components for reliable hydrogen technology. Under current regulations, a mostly conservative strategy is employed, restricting the usage time of hydrogen pressure vessels without providing information on the real remaining lifetime. During the service life, pressure vessels are inspected periodically. However, no established method that can provide continuous monitoring or information on the remaining safe service life of the vessel. In this paper, we propose a sensor network for Structural Health Monitoring (SHM) of hydrogen pressure vessels where data from all sensors are collected and centrally evaluated. Specifically, we integrate three different SHM sensing technologies namely Guided Wave ultrasonics (GW), Acoustic Emission testing (AT), and distributed Fiber Optic Sensing (FOS). This integrated approach offers significantly more information and could therefore enable a transition from costly and time-consuming periodic inspections to more efficient and modern predictive maintenance strategies, including Artificial Intelligence (AI)-based evaluation. This does not only have a positive effect on the operational costs but enhances safety through early identification of critical conditions in the overall system in real-time. We demonstrate an experimental set-up of a lifetime test where a Type IV Composite Overwrapped Pressure Vessel (COPV) is investigated under cyclic loading instrumented with AT, FOS, and GW methods. We acquired data from the sensor network until the pressure vessel failed due to material degradation. The data collected using the three different SHM sensor technologies is planned to be evaluated individually, using data fusion, and AI. In the future, we aim to integrate the measurement setup into a hydrogen refueling station with the data stream implemented into a digital signal processing chain and a digital twin. T2 - 11th European Workshop on Structural Health Monitoring CY - Potsdam, Germany DA - 10.06.2024 KW - Hydrogen KW - Ultrasonic guided waves KW - Fiber optic sensors KW - Acoustic emission KW - Machine learning KW - Pressure vessels KW - Structural health monitoring PY - 2024 AN - OPUS4-60277 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Karapanagiotis, Christos T1 - Structural health monitoring of hydrogen pressure vessels using distributed fiber optic sensing N2 - We report on distributed fiber optic sensing-based monitoring of hydrogen composite overwrapped pressure vessels (COPV) to simultaneously increase the operational lifespan and mitigate maintenance costs. Our approach represents, to the best of our knowledge, the first application of distributed fiber optic sensing for COPV Type IV monitoring, where the sensing fibers are attached to the surface, rather than integrated into the composite material. Specifically, we attach an optical fiber of 50 m to the pressure vessel's surface, covering both the cylindrical and dome sections. We note that our fiber optic sensing technique relies on swept wavelength interferometry providing strain information along the entire length of the optical fiber with high spatial resolution even at the millimeter scale. When the vessel is pressurized, the sensing optical fiber shows a linear strain response to pressure at every position along the fiber. After thousands of load cycles, the vessel finally fails with the optical fiber detecting and precisely localizing the damage in the vessel’s blind dome area. Furthermore, we discuss the potential of state-of-the-art signal processing methods and machine learning for advancing predictive maintenance. This could reduce the number of regular inspections, mitigate premature maintenance costs, and simultaneously increase the vessel’s remaining safe service life. We believe that the structural health monitoring of hydrogen pressure vessels with fiber optic sensors can enhance trust in hydrogen technology contributing to the energy transition in the future. T2 - 11th European Workshop on Structural Health Monitoring CY - Potsdam, Germany DA - 10.06.2024 KW - Hydrogen KW - Composites KW - Pressure vessels KW - Fiber optic sensors KW - Machine learning KW - Structural health monitoring PY - 2024 AN - OPUS4-60275 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wosniok, Aleksander T1 - Distributed fiber optic strain sensing for structural health monitoring of 70 MPa hydrogen vessels N2 - We report on the development and testing of 70 MPa hydrogen pressure vessels with integrated fiber optic sensing fibers for automotive use. The paper deals with the condition monitoring of such composite pressure vessels (CPVs) using the optical backscatter reflectometry (OBR) applied for a distributed fiber optic strain sensing along fully integrated polyimide-coated single-mode glass optical fiber (SM-GOF). The sensing fibers were embedded into the vessel structure by wrapping them over the polymer liner during the manufacturing process of the carbon fiber reinforced polymer (CFRP). Detecting local strain events by the integrated fiber optic sensors can be an opportunity for monitoring the material degradation of CPVs under static and cyclic loading. T2 - 11th European Workshop on Structural Health Monitoring CY - Potsdam, Germany DA - 10.06.2024 KW - Fiber optic sensor KW - Distributed strain sensing KW - Composite pressure vessel KW - Structural health monitoring KW - Fiber-reinforced plastics PY - 2024 AN - OPUS4-60307 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heimann, Jan A1 - Yilmaz, Bengisu A1 - Charmi, Amir A1 - Duffner, Eric A1 - Schukar, Marcus A1 - Prager, Jens T1 - Structural Health Monitoring (SHM) for continuous monitoring of hydrogen pressure vessels N2 - While hydrogen is one of the most promising energy carriers, the safety of hydrogen storage technology remains one of the most important factors for technological and societal approval. While the engineering safety factors of the pressure vessels are kept high, the periodic inspection and the limited lifetime are making the application very costly considering manpower, time, money, and material waste. The development of an integrated structural health monitoring system can allow an easy transition from the current situation to cost-effective predictive maintenance. Hence, we propose to integrate three different SHM systems into hydrogen pressure vessels, namely guided wave ultrasonics, acoustic emission, and fibre optic sensing, to continuously monitor the condition and integrity. In this work, we evaluated the condition of a Type IV composite overwrapped pressure vessel using ultrasonic guided wave propagation. We mounted fifteen piezo-electric wafers on the composite cylinder by shaping three rings containing five sensors each. We acquired data from the sensor network following different boundary conditions with artificial damages on the selected locations. The data were evaluated with guided wave tomography techniques using ultrasonic features (amplitude, frequency, etc.) as well as artificial intelligence (AI). The results suggest that both traditional guided wave fusion techniques and AI-based characterization methods can detect artificial damages. In future work, it is planned to integrate acoustic emission and fibre optic sensing. Moreover, the measurement and the test results will be implemented into a digital twin to derive trends and make predictions on the damage propagation as well as the remaining useful lifetime. This work has received funding from German Ministry of Economic Affairs and Climate Actions within the QI-Digital initiative (www.qi-digital.de). T2 - SCHALL 23 CY - Wetzlar, Germany DA - 21.03.2023 KW - Structural Health Monitoring KW - Ultrasonic Guided Waves KW - Composite Overwrapped Pressure Vessel KW - Hydrogen PY - 2023 AN - OPUS4-58026 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Karapanagiotis, Christos A1 - Schukar, Marcus A1 - Breithaupt, Mathias A1 - Krebber, Katerina T1 - Monitoring of composite pressure vessels using surface applied distributed fiber optic sensors N2 - In this paper, we report on surface-applied distributed fibre optic sensors for monitoring composite pressure vessels designed for hydrogen storage. Previous reports have revealed that integrating optical fibres within vessel composite structures effectively enables the monitoring of structural behavior throughout their lifetime. However, integrating optical fibres during the manufacturing process is complex and time-consuming. Therefore, we aim to simplify this process by attaching the optical fibres to the vessel’s surface. This method is significantly more timeefficient than the integration process and can be applied to any vessel. Our results demonstrate that surface-applied fibre optic sensors can detect and precisely localise damage. Additionally, signs of damage can be recognised even before the damage occurs. Predictive maintenance using fibre optic sensors could reduce premature maintenance costs and periodic inspections while increasing safety and extending the vessel’s useful service life. The role of machine learning in predictive maintenance is also discussed. T2 - 20th Sensors & their Applications Conference CY - Limerick, Ireland DA - 11.08.2024 KW - Hydrogen KW - Fiber optic sensors KW - Composites KW - Machine learning KW - Structural health monitoring PY - 2024 SP - 1 EP - 4 AN - OPUS4-60911 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Karapanagiotis, Christos T1 - Monitoring hydrogen composite pressure vessels using surface applied distributed fiber optic sensors N2 - We report on surface-applied distributed fibre optic sensors for monitoring composite pressure vessels designed for hydrogen storage. Previous reports have revealed that integrating optical fibres within vessel composite structures effectively enables the monitoring of structural behavior throughout their lifetime. However, integrating optical fibres during the manufacturing process is complex and time-consuming. Therefore, we aim to simplify this process by attaching the optical fibres to the vessel’s surface. This method is significantly more timeefficient than the integration process and can be applied to any vessel. Our results demonstrate that surface-applied fibre optic sensors can detect and precisely localise damage. Additionally, signs of damage can be recognised even before the damage occurs. Predictive maintenance using fibre optic sensors could reduce premature maintenance costs and periodic inspections while increasing safety and extending the vessel’s useful service life. The role of machine learning in predictive maintenance is also discussed. T2 - 20th Sensors & their Applications Conference CY - Limerick, Ireland DA - 11.08.2024 KW - Hydrogen KW - Fiber optic sensors KW - Composites KW - Machine learning KW - Structural health monitoring PY - 2024 AN - OPUS4-60831 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wosniok, Aleksander T1 - WP6 Different Components and System Prototyping N2 - We report on the development and testing of 70 MPa hydrogen pressure vessels with integrated fibre optic sensors for automotive use as a part of the European SH2APED project. The most research results were achieved in the framework of the Work Package 6. T2 - General Assembly Project SH2APED CY - Brussels, Belgium DA - 25.09.2024 KW - Composite pressure vessel KW - Fibre optic sensor KW - Distributed strain sensing KW - Structural health monitoring KW - Optical backscatter reflectometry PY - 2024 AN - OPUS4-61212 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wosniok, Aleksander T1 - Distributed fibre optic strain sensing for structural health monitoring of composite pressure vessels N2 - We report on the development and testing of 70 MPa hydrogen pressure vessels with integrated fibre optic sensors for automotive use. The research results were achieved in the framework of the European project SH2APED. T2 - Stakeholders' Workshop SH2APED CY - Brussels, Belgium DA - 26.09.2024 KW - Composite pressure vessel KW - Fibre optic sensor KW - Distributed strain sensing KW - Structural health monitoring KW - Fibre-reinforced plastics PY - 2024 AN - OPUS4-61211 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Königsbauer, Korbinian T1 - Distributed fiber optic sensing as a new approach for comprehensive multi-parameter monitoring of underground hydrogen storage facilities N2 - Hydrogen plays a significant role in the green energy transition and energy independence. Underground hydrogen storage facilities are of great importance for the hydrogen network, as they can store and regulate large quantities of gas. Due to the high explosion risk associated with hydrogen, these facilities need to be closely monitored to avoid any hazardous consequences, such as leaks or explosions. However, it is extremely challenging to perform a comprehensive, seamless and continuous monitoring of the facilities in practice. Distributed fiber optic sensors (DFOSs) are well-suited to address these challenges. The DFG project MUDFOS aims to develop a hybrid DFOS system capable of simultaneously and accurately measuring five key parameters (hydrogen concentration, temperature, strain, humidity, and vibration) that are critical for hydrogen infrastructure over long sensing distances based on Raman-, Rayleigh- and Brillouin-scattering effects. T2 - Kolloquium H2Safety@BAM CY - Online meeting DA - 16.07.2025 KW - Distributed Fiber Optic Sensing KW - Monitoring of Hydrogen Storage Facilities KW - Multi-Parameter Monitoring KW - Raman-, Rayleigh- and Brillouin-Scattering PY - 2025 AN - OPUS4-63748 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bernardy, Christopher A1 - Konert, Florian A1 - Popiela, Bartosz A1 - Sarif, Raduan T1 - H2Safety@BAM: Competence Center for safe hydrogen technologies N2 - Presentation of the competence center H2Safety@BAM at the European PhD Hydrogen Conference 2024 in Ghent, Belgium. T2 - European PhD Hydrogen Conference 2024 (EPHyC2024) CY - Ghent, Belgium DA - 20.03.2024 KW - H2safety KW - Hydrogen KW - Safety KW - Competence center PY - 2024 AN - OPUS4-59756 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hatz, N. T1 - Automatisierte zerstörungsfreie Innenkorrosionserkennung an radioaktiven Fassgebinden N2 - Im Rahmen der Fördermaßnahme „FORKA – Forschung für den Rückbau kerntechnischer Anlagen“ entwickeln das Karlsruher Institut für Technologie (KIT) zusammen mit den Projektpartnern der Bundesanstalt für Materialforschung (BAM), der Kraftanlagen Heidelberg GmbH (KAH) und der Landessammelstelle Berlin (ZRA) ein automatisiertes und auf zerstörungsfreien Prüfverfahren basierendes Fassinspektionssystem im Projekt ZIKA. Dieses System ermöglicht es, den aktuellen Zustand einzelner Fassgebinde auf genau dieselbe reproduzierbare Weise zu bestimmen und zu dokumentieren. Es trägt bei gleichzeitiger Erhöhung der Arbeitssicherheit zu einer Optimierung der wiederkehrenden Prüfungen durch Vereinheitlichungen und Reproduzierbarkeit bei. Zusätzlich kann durch eine Innenkorrosionserkennung frühzeitig Schäden erkannt werden, die bei einer regulären Inspektion nicht feststellbar wären. In Rahmen des Vorgängerprojekts EMOS wurde bereits eine Demonstrationsanlage zur Fassinspektion in einen geschlossenen Container gebaut, die über ein Bedienpanel gesteuert wird und es ermöglicht, das Äußere des Fasses zu inspizieren. Ziel von ZIKA ist es, die Erkenntnisse aus EMOS zu nutzen und eine Innenkorrosionserkennung zu integrieren, sowie das Gesamtsystem zu verkleinern. Zur Innenkorrosionserkennung werden an Testkörpern verschiedene zerstörungsfreie Prüfverfahren evaluiert und auf deren Eignung bewertet. Zu den Prüfverfahren gehören Thermografie, verschiedene Ultraschallprüftechniken, magnetische Streuflussmessung und Wirbelstromprüfung. T2 - KONTEC 2025 - Internationales Symposium Konditionierung radioaktiver Betriebs- und Stilllegungsabfälle & Stilllegung kerntechnischer Anlagen CY - Dresden, Germany DA - 17.09.2025 KW - Thermografie KW - Laserthermografie KW - ZfP KW - Machine learning PY - 2025 AN - OPUS4-64127 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lay, Vera A1 - Baensch, Franziska A1 - Johann, Sergej A1 - Sturm, Patrick A1 - Mielentz, Frank A1 - Prabhakara, Prathik A1 - Hofmann, Detlef A1 - Niederleithinger, Ernst A1 - Kühne, Hans-Carsten T1 - SealWasteSafe: materials technology, monitoring techniques, and quality assurance for safe sealing structures in underground repositories N2 - Within the project SealWasteSafe, we advance construction materials and monitoring concepts of sealing structures applied for underground disposal of nuclear or toxic waste. As these engineered barriers have high demands concerning integrity, an innovative alkali-activated material (AAM) is improved and tested on various laboratory scales. This AAM has low reaction kinetics related to a preferential slow release of the heat of reaction in comparison to alternative salt concretes based on Portland cement or magnesium oxychloride cements. Hence, crack formation due to thermally induced strain is reduced. After successful laboratory scale analysis (Sturm et al., 2021), the AAM is characterised on a larger scale by manufacturing test specimens (100–300 L). Conventional salt concrete (DBE, 2004) and the newly developed AAM are compared using two specimen geometries, i.e. cylindrical and cuboid. A comprehensive multisensor monitoring scheme is developed to compare the setting process of AAM and salt concrete for these manufactured specimens. The analysed parameters include temperature and humidity of the material, acoustic emissions, and strain variations. Passive sensor systems based on radiofrequency identification technology (RFID) embedded in the concrete, enable wireless access to temperature and humidity measurements and are compared to conventional cabled systems. Additionally, fibre-optic sensors (FOS) are embedded to record strain, but also have potential to record temperature and moisture conditions. Part of this project aims at demonstrating the high reliability of sensors and also their resistance to highly alkaline environments and to water intrusion along cables or at sensor locations. Further technical improvements were implemented so that first results clearly show the scalability of the setting process from previous small-scale AAM experiments and particularly the high potential of the newly developed approaches. Furthermore, ultrasonic methods are used for quality assurance to detect obstacles, potential cracks and delamination. On the one hand, both active and passive ultrasonic measurements complement the results obtained from the multisensor monitoring scheme for the produced specimens. On the other hand, the unique large aperture ultrasonic system (LAUS) provides great depth penetration (up to nearly 10 m) and can thus be applied at in situ sealing structures built as a test site in Morsleben by the Federal Company for Radioactive Waste Disposal (Bundesgesellschaft für Endlagerung, BGE) as shown by Effner et al. (2021). An optimised field lay-out identified from forward modelling studies and advanced imaging techniques applied to the measured data will further improve the obtained results. To characterise the inside of the test engineered barrier and achieve a proof-of-concept, an ultrasonic borehole probe is developed to enable phased arrays that can further improve the detection of potential cracks. Modelling results and first analysis of semispherical specimens confirmed the reliability of the directional response caused by the phased arrays of the newly constructed ultrasonic borehole probe. Overall, the project SealWasteSafe improves the construction material, multisensor monitoring concepts and ultrasonics for quality assurance. This will help to develop safe sealing structures for nuclear waste disposal. The outcomes are particularly valuable for salt as a host rock but partly also transferrable to alternative conditions. T2 - Safe ND Interdisciplinary research symposium on the safety of nuclear disposal practices CY - Berlin, Germany DA - 10.11.2021 KW - Borehole probe KW - SealWasteSafe KW - Engineered barrier KW - Materials technology KW - Monitoring KW - AAM KW - Ultrasound PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-539172 DO - https://doi.org/10.5194/sand-1-127-2021 VL - 1 SP - 127 EP - 128 PB - Copernicus AN - OPUS4-53917 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Chaudhuri, Somsubhro T1 - Infrared thermography as an inspection tool for wind turbine rotor blades N2 - This presentation explores the use of infrared thermography as an inspection tool for wind turbine rotor blades. It highlights the implementation of ground-based thermographic techniques, demonstrates what can be achieved through such inspections, and presents a case study conducted in partnership with Statkraft. Particular attention is given to the discussion of thermal contrast and how it can be obtained for effective defect detection. To assess the potential and limitations of thermography, results from controlled climate chamber experiments and complementary simulations are also presented. T2 - IQPC Wind Week 2025 CY - Bremen, Germany DA - 26.08.2025 KW - Thermography KW - Thermografie KW - Wind turbine rotor blades KW - Windenergie anlage rotorblätte KW - Damage detection PY - 2025 AN - OPUS4-64056 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Prabhakara, Prathik A1 - Mielentz, Frank A1 - Stolpe, Heiko A1 - Behrens, Matthias A1 - Lay, Vera A1 - Niederleithinger, Ernst T1 - Ultrasonic Investigation for the Quality Assurance of Sealing Structures in Radioactive Waste Repositories N2 - The structural integrity of sealing structures in underground repositories for radioactive waste is a major concern regarding safe disposal. Non-destructive testing plays a very important role in the safety of this sealing structures. Ultrasonic pulse echo technology has been established in the construction industry as a non-destructive testing method for locating potential defects and material characterization of concrete structures. A borehole probe is an ultrasonic pulse-echo device used to investigate the internal structures of salt concrete. A prototype borehole probe is successfully demonstrated with the existing research borehole in the test site using a commercially available flaw detector. A novel phased array borehole probe that allows the beam to be focused based on the delay law was constructed and tested. The directivity measurements on the semi-cylindrical concrete sample agree well with the simulation results for the different focusing angles. In combination with geophysical reconstruction methods, the optimized radiation pattern of the probe is expected to improve the signal quality and thus increase the reliability of the imaging results. In addition, a unique large aperture ultrasound system (LAUS) is expected to provide enhanced images of possible cracks and embedded objects in in-situ structures. LAUS will be optimized to reliably detect objects at depths greater than 9 m and, at the same time, provide good resolution. Modeling studies show the potential to increase the distance between the transducer arrays further, and the same configuration has been successfully tested on a thick concrete wall. Overall, the paper shows that quality assurance using ultrasonic testing is crucial for constructing safe sealing structures to dispose of radioactive or toxic waste. T2 - NDE 2022 CY - Gandhinagar, India DA - 24.12.2022 KW - Ultrasonic Testing KW - Engineered barrier KW - Phased array technique KW - Non-destructive testing civil engineering KW - Quality assurance PY - 2022 AN - OPUS4-56802 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mielentz, Frank A1 - Stolpe, Heiko A1 - Effner, Ute A1 - Behrens, Matthias A1 - Bernstein, Thomas A1 - Niederleithinger, Ernst T1 - Entwicklung einer Bohrlochsonde für Ultraschalluntersuchungen an Abschlussbauwerken in Endlagern N2 - Für die Qualitätssicherung von Abschlusswerken für Endlager wird eine Ultraschall-Bohrlochsonde entwickelt. Mithilfe dieser Sonde, die aus einer Vielzahl von einzelnen koppelmittelfreien Ultraschall-Punktkontaktprüfköpfen besteht, soll die Rissfreiheit der Versuchsbauwerke überprüft werden. Ein erster Prototyp der Sonde wurde mit einem kommerziellen Ultraschallgerät betrieben und bestand aus 12 Transversalwellen-Punktkontaktprüfköpfen von denen jeweils sechs als Sender und sechs als Empfänger parallelgeschaltet waren. Um den erzeugten Schalldruck der Bohrlochsonde zu steigern, wurde bei der Neuentwicklung die Prüfkopfanzahl erhöht und zusätzlich die laufzeitgesteuerte Anregung der einzelnen Prüfköpfe vorgesehen. Für die Anregung der Prüfköpfe mit programmierten Zeitverzögerungen wurde ein neuartiger mehrkanaliger Sender für bipolare Rechtecksignale entwickelt. Durch die Entwicklung der Bohrlochsonde soll eine dynamische Anpassung der Prüfkopf-Apertur sowie eine Fokussierung des Schallfeldes in Abhängigkeit der zu untersuchenden Tiefe erfolgen. Mithilfe entsprechender Anregungsfunktionen kann das Schallfeld der Bohrlochsonde unterschiedlich geformt werden, z. B. ist auch ein Schwenken des fokussierten Schallbündels möglich. Dadurch wird das erfasste Prüfvolumen begrenzt und auf diese Weise das Signal-Störverhältnis der Empfangssignale verbessert. In Kombination mit SAFT-Rekonstruktionsrechnungen wird durch eine optimierte Abstrahlcharakteristik der Sonde mit einem hohen Schalldruck unter verschiedenen Winkeln eine verbesserte Signalqualität und damit eine erhöhte Aussagesicherheit der Ergebnisse in der Objektabbildung erwartet. T2 - DGZfP-Jahrestagung 2021 CY - Online meeting DA - 10.05.2021 KW - Abdichtbauwerk KW - Bohrlochsonde KW - Ultraschall-Echoverfahren KW - Verschlussbauwerk KW - Zerstörungsfreie Prüfung KW - Ultraschall-Messtechnik PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-526746 UR - https://jahrestagung.dgzfp.de/portals/jt2021/bb176/inhalt/poster.htm SN - 978-3-947971-18-3 VL - 176 SP - 1 EP - 7 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) CY - Berlin AN - OPUS4-52674 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Büttner, C. A1 - Niederleithinger, Ernst A1 - Buske, S. A1 - Friedrich, C. T1 - Ultrasonic Echo Localization Using Seismic Migration Techniques in Engineered Barriers for NuclearWaste Storage N2 - In the framework of non-destructive-testing advanced seismic imaging techniques have been applied to ultrasonic echo data in order to examine the integrity of an engineered test-barrier designed to be used for sealing an underground nuclear waste disposal site. Synthetic data as well as real multi-receiver ultrasonic data acquired at the test site were processed and imaged using Kirchhoff prestack depth migration reverse time migration (RTM). In general, both methods provide a good Image quality as demonstrated by various case studies, however deeper parts within the test barrier containing inclined reflectors were reconstructed more accurately by RTM. In particular, the image quality of a specific target reflector at a depth of 8 m in the test-barrier has been significantly improved compared to previous investigations using synthetic aperture Focusing technique, which justifies the considerable computing time of this method. KW - Radioactive waste disposal KW - Engineered barrier KW - Ultrasound KW - Imaging KW - Crack detection PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-537956 DO - https://doi.org/10.1007/s10921-021-00824-3 SN - 0195-9298 VL - 40 IS - 4 SP - 1 EP - 10 PB - Springer AN - OPUS4-53795 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Prabhakara, Prathik A1 - Lay, Vera A1 - Mielentz, Frank A1 - Niederleithinger, Ernst A1 - Behrens, Matthias T1 - Enhancing the Performance of a Large Aperture Ultrasound System (LAUS): A Combined Approach of Simulation and Measurement for Transmitter–Receiver Optimization N2 - The Large Aperture Ultrasound System (LAUS) developed at BAM is known for its ability to penetrate thick objects, especially concrete structures commonly used in nuclear waste storage and other applications in civil engineering. Although the current system effectively penetrates up to ~9 m, further optimization is imperative to enhance the safety and integrity of disposal structures for radioactive or toxic waste. This study focuses on enhancing the system’s efficiency by optimizing the transducer spacing, ensuring that resolution is not compromised. An array of twelve horizontal shear wave transducers was used to find a balance between penetration depth and resolution. Systematic adjustments of the spacing between transmitter and receiver units were undertaken based on target depth ranges of known reflectors at depth ranges from 5 m to 10 m. The trade-offs between resolution and artifact generation were meticulously assessed. This comprehensive study employs a dual approach using both simulations and measurements to investigate the performance of transducer units spaced at 10 cm, 20 cm, 30 cm, and 40 cm. We found that for depths up to 5 m, a spacing of 10 cm for LAUS transducer units provided the best resolution as confirmed by both simulations and measurements. This optimal distance is particularly effective in achieving clear reflections and a satisfactory signal-to-noise ratio (SNR) in imaging scenarios with materials such as thick concrete structures. However, when targeting depths greater than 10 m, we recommend increasing the distance between the transducers to 20 cm. This increased spacing improves the SNR in comparison to other spacings, as seen in the simulation of a 10 m deep backwall. Our results emphasize the critical role of transducer spacing in achieving the desired SNR and resolution, especially in the context of depth imaging requirements for LAUS applications. In addition to the transducer spacing, different distances between individual sets of measurement positions were tested. Overall, keeping the minimal possible distance between measurement position offsets provides the best imaging results at greater depths. The proposed optimizations for the LAUS in this study are primarily relevant to applications on massive nuclear structures for nuclear waste management. This research highlights the need for better LAUS efficiency in applications such as sealing structures, laying the foundation for future technological advances in this field. KW - Engineered barrier system KW - Phased array technique KW - Ultrasonic testing KW - Non-destructive testing in civil engineering KW - Seismic migration PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-592426 DO - https://doi.org/10.3390/s24010100 VL - 24 IS - 1 SP - 1 EP - 23 PB - MDPI CY - Basel, Switzerland AN - OPUS4-59242 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lay, Vera A1 - Effner, Ute A1 - Niederleithinger, Ernst A1 - Arendt, J. A1 - Hofmann, M. A1 - Kudla, W. T1 - Ultrasonic quality assurance at magnesia shotcrete sealing structures N2 - Engineered barriers are a key element to enable safe nuclear waste disposal. One method currently under research for their construction is magnesia concrete applied in a shotcrete procedure. In this study, the ultrasonic echo method is evaluated as a means for quality assurance. Imaging of internal structures (backwall, boreholes) and defects, such as delamination, has successfully been achieved in the shotcrete. Additionally, detailed information about the potential cause of selected reflectors are obtained by phase analysis. In several test blocks of various sizes, no consistent concrete section boundaries have been found by ultrasonic imaging, which was verified by subsequent drilling and complementary tests. An experiment with artificial defects imitating cracks, air-filled voids, and material with lower density has been challenging and shows the limitations of the current methods. Although significant defects, such as a large delamination, are reliably identified, several smaller defects are not identified. Generally, ultrasonic imaging provides a suitable base as a mean for quality assurance during and after the construction of sealing structures. However, further developments are required to enhance the reliability of the method and a full validation is still pending. Still, the method has potential to increase the safety of nuclear waste repositories. KW - Ultrasound KW - Imaging KW - Engineered barrier systems KW - Underground KW - Shotcrete PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-563170 DO - https://doi.org/10.3390/s22228717 SN - 1424-8220 VL - 22 IS - 22 SP - 1 EP - 16 PB - MDPI CY - Basel AN - OPUS4-56317 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lay, Vera A1 - Effner, Ute A1 - Niederleithinger, Ernst A1 - Arendt, J. A1 - Kudla, W. T1 - Ultrasonic quality assurance for underground salt shotcrete sealing structures in Teutschenthal mine, Germany N2 - Underground sealing structures are necessary to seal radioactive or toxic waste in underground repositories. A special version of MgO concrete is used in the mine in Teutschenthal and applied at a large-scale test with the aim to provide a low permeability barrier. The test structures (up to 10 m long) were created by shotcreting. Besides destructive tests, non-destructive ultrasonic measurements have been evaluated for quality assurance to monitor potential anomalies such as cracks, concrete inhomogeneities, and delamination. We show results of ultrasonic measurements with a multi-transducer system used at the front and from the side of the concrete structure. Images are obtained by synthetic aperture focusing techniques. The boundaries between concreting sections are not visible in the ultrasonic images systematically so that a successful concreting is assumed, which is confirmed by the low permeabilities observed. Several reflectors up to a depth of 1.2 m are identified and interpreted as potential damages in the concrete. Phase analysis of prominent reflectors reveal a negative impedance contrast thus indicating air filled voids, cracks or delamination. Boreholes through some of the identified reflectors are used to verify the results from ultrasonic measurements. Additionally, an experiment with incorporated artificial defects was undertaken to analyse the reliability of the applied methods. Overall, the conducted tests show the potential of ultrasonic measurements to detect critical anomalies. Despite challenges at small-scale structures (cm-order), large-scale anomalies can be identified. Consequently, implementing ultrasonic monitoring during and after the construction of concrete sealing structures has shown its potential as a tool for quality assurance, but needs further development and validation. T2 - NDT-CE 2022 CY - Zurich, Switzerland DA - 16.08.2022 KW - Ultrasound KW - Ultrasonic imaging KW - Magnesia shotcrete KW - Underground KW - Engineered barrier systems PY - 2022 UR - https://www.ndt.net/events/proceedings/topic.php?eventID=292&TopicID=27209 SP - 1 EP - 4 PB - NDT.net AN - OPUS4-55824 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kolditz, O. A1 - Jacques, D. A1 - Claret, F. A1 - Bertrand, J. A1 - Churakov, S. V. A1 - Debayle, C. A1 - Diaconu, D. A1 - Fuzik, K. A1 - Garcia, D. A1 - Graebling, N. A1 - Grambow, B. A1 - Holt, E. A1 - Idiart, A. A1 - Leira, P. A1 - Montoya, V. A1 - Niederleithinger, Ernst A1 - Olin, M. A1 - Pfingsten, W. A1 - Prasianakis, N. I. A1 - Rink, K. A1 - Sampier, J. A1 - Szöke, I. A1 - Szöke, R. A1 - Theodon, L. A1 - Wendling, J. T1 - Digitalisation for nuclear waste management: predisposal and disposal N2 - Data science (digitalisation and artificial intelligence) became more than an important facilitator for many domains in fundamental and applied sciences as well as industry and is disrupting the way of research already to a large extent. Originally, data sciences were viewed to be well-suited, especially, for data-intensive applications such as image processing, pattern recognition, etc. In the recent past, particularly, data-driven and physics-inspired machine learning methods have been developed to an extent that they accelerate numerical simulations and became directly usable for applications related to the nuclear waste management cycle. In addition to process-based approaches for creating surrogate models, other disciplines such as virtual reality methods and high-performance computing are leveraging the potential of data sciences more and more. The present challenge is utilising the best models, input data and monitoring information to integrate multi-chemical-physical, coupled processes, multi-scale and probabilistic simulations in Digital Twins (DTw) able to mirror or predict the performance of its corresponding physical twins. Therefore, the main target of the Topical Collection is exploring how the development of DTw can benefit the development of safe, efficient solutions for the pre-disposal and disposal of radioactive waste. A particular challenge for DTw in radioactive waste management is the combination of concepts from geological modelling and underground construction which will be addressed by linking structural and multi-physics/chemistry process models to building or tunnel information models. As for technical systems, engineered structures a variety of DTw approaches already exist, the development of DTw concepts for geological systems poses a particular challenge when taking the complexities (structures and processes) and uncertainties at extremely varying time and spatial scales of subsurface environments into account. KW - Data science KW - Digitalization KW - Nuclear waste KW - Disposal KW - Predisposal PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-569387 DO - https://doi.org/10.1007/s12665-022-10675-4 SN - 1866-6280 VL - 82 IS - 1 SP - 1 EP - 11 PB - Springer AN - OPUS4-56938 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Prabhakara, Prathik A1 - Mielentz, Frank A1 - Stolpe, Heiko A1 - Behrens, Matthias A1 - Lay, Vera A1 - Niederleithinger, Ernst T1 - Validation of novel ultrasonic phased array borehole probe by using simulation and measurement N2 - Low-frequency ultrasonic testing is a well-established non-destructive testing (NDT) method in civil engineering for material characterization and the localization of cracks, reinforcing bars and delamination. A novel ultrasonic borehole probe is developed for in situ quality assurance of sealing structures in radioactive waste repositories using existing research boreholes. The aim is to examine the sealing structures made of salt concrete for any possible cracks and delamination and to localize built-in components. A prototype has been developed using 12 individual horizontal dry point contact (DPC) shear wave transducers separated by equidistant transmitter/receiver arrays. The probe is equipped with a commercially available portable ultrasonic flaw detector used in the NDT civil engineering industry. To increase the sound pressure generated, the number of transducers in the novel probe is increased to 32 transducers. In addition, the timed excitation of each transducer directs a focused beam of sound to a specific angle and distance based on the previously calculated delay time. This narrows the sensitivity of test volume and improves the signal-to-noise ratio of the received signals. In this paper, the newly designed phased array borehole probe is validated by beam computation in the CIVA software and experimental investigations on a half-cylindrical test specimen to investigate the directional characteristics. In combination with geophysical reconstruction methods, it is expected that an optimised radiation pattern of the probe will improve the signal quality and thus increase the reliability of the imaging results. This is an important consideration for the construction of safe sealing structures for the safe disposal of radioactive or toxic waste. KW - Ultrasound KW - Phased array KW - Concrete KW - Borehole PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-565722 DO - https://doi.org/10.3390/s22249823 SN - 1424-8220 VL - 22 IS - 24 SP - 1 EP - 16 PB - MDPI CY - Basel AN - OPUS4-56572 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Holt, E. A1 - Oksa, M. A1 - Nieminen, M. A1 - Abdelouas, A. A1 - Banford, A. A1 - Fournier, M. A1 - Mennecart, T. A1 - Niederleithinger, Ernst T1 - Predisposal conditioning, treatment, and performance assessment of radioactive waste streams N2 - Before the final disposal of radioactive wastes, various processes can be implemented to optimise the waste form. This can include different chemical and physical treatments, such as thermal treatment for waste reduction, waste conditioning for homogenisation and waste immobilisation for stabilisation prior to packaging and interim storage. Ensuring the durability and safety of the waste matrices and packages through performance and condition assessment is important for waste owners, waste management organisations, regulators and wider stakeholder communities. Technical achievements and lessons learned from the THERAMIN and PREDIS projects focused on low- and intermediate-level waste handling is shared here. The recently completed project on Thermal Treatment for Radioactive Waste Minimization and Hazard Reduction (THERAMIN) made advances in demonstrating the feasibility of different thermal treatment techniques to reduce volume and immobilise different streams of radioactive waste (LILW) prior to disposal. The Pre-Disposal Management of Radioactive Waste (PREDIS) project addresses innovations in the treatment of metallic materials, liquid organic waste and solid organic waste, which can result from nuclear power plant operation, decommissioning and other industrial processes. The project also addresses digitalisation solutions for improved safety and efficiency in handling and assessing cemented-waste packages in extended interim surface storage. KW - Radioactive waste KW - Predisposal KW - Treatment KW - Monitoring PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-567276 DO - https://doi.org/10.1051/epjn/2022036 SN - 2491-9292 VL - 8 SP - 1 EP - 6 PB - EDP Sciences CY - Les Ulis AN - OPUS4-56727 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lay, Vera A1 - Baensch, Franziska A1 - Skłodowska, Anna A1 - Fritsch, Tobias A1 - Stamm, Michael A1 - Prabhakara, Prathik A1 - Johann, Sergej A1 - Sturm, Patrick A1 - Kühne, Hans-Carsten A1 - Niederleithinger, Ernst T1 - Multi–sensory Monitoring and Non–destructive Testing of New Materials for Concrete Engineered Barrier Systems N2 - The crucial part of nuclear waste storage is the construction of sealing structures made of reliable, safe and well–understood materials. We present an extended analysis of long-term multi–sensory monitoring and non–destructive testing (NDT) inspection of two laboratory specimens aiming at potential materials for sealing structures for nuclear waste repositories. Specimens with a volume of 340 litres made from newly developed alkali–activated materials (AAM) and established salt concrete (SC) were analysed using embedded acoustic emission and wireless radio-frequency identification (RFID) sensors, ultrasonic echo imaging, active thermography, and X–ray computed tomography. The monitoring analysis showed lower heat of reaction and 50% less acoustic emission events in AAM compared to SC. However, due to the surface effects of the AAM material, the number of acoustic emission events increased significantly after approximately two months of monitoring. Subsequently performed NDT inspections reliably located embedded sensors and confirmed the absence of major cracks or impurities. The presented laboratory results show the feasibility and potential of comprehensive NDT monitoring and inspection to characterise cementitious and alternative materials as well as the need for multi–parameter long–term monitoring. Thus, our study demonstrates that tailored NDT investigations will help to develop safe sealing structures for nuclear waste repositories. KW - Radioactive waste KW - Barrier KW - Concrete KW - AAM KW - Non-destructive testing PY - 2024 DO - https://doi.org/10.3151/jact.22.516 SN - 1347-3913 VL - 22 IS - 9 SP - 516 EP - 529 PB - Japan Concrete Institute AN - OPUS4-61461 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Holt, Erika A1 - Oksa, Maria A1 - Banford, Anthony A1 - Carbol, Paul A1 - Abdelouas, Abdesselam A1 - Giboire, Isabelle A1 - Mennecart, Thierry A1 - Niederleithinger, Ernst T1 - Predisposal Radioactive Waste Management (PREDIS) Project Final Achievements and Impacts Overview N2 - The PREDIS project on Predisposal of Radioactive Waste has succeeded in developing and implementing new methods, processes and technologies for treatment of challenging low-level waste (LLW) and intermediate level waste (ILW) streams. Over the 4-year duration, this Euratom project of 47 partners from 17 Member States has worked in close collaboration with 25 End User industrial members to advance the technologies associated with predisposal issues. This has included characterisation followed by treatment, conditioning and processing of metallics, liquid organic and solid organic wastes as well as with digitalization technologies for assessing performance of concrete waste packages and pre-disposal storage. Long-term modelling and performance testing have been done to verify the safety and effectiveness of the new or enhanced solutions. Value Assessments were done for some of the new solutions to ensure implementors would have sufficient tools for making choices about the potential implementation. This included life-cycle assessment of quantitative sustainability indicators and life cycle-costing for economic indicators. This project addressed new guidance on Waste Acceptance Criteria and contributed with a revised Strategic Research Agenda to guide future predisposal activities, complimentary to the holistic waste management programme. Knowledge Management actions were also an integral part of the whole project to foster competence development and capturing knowledge. Actions included training, mobility, and guidance especially through online forums such as webinars and digital training. This paper provides a snapshot of some of the key outcomes and impacts from the project, from technical as well as strategic and knowledge perspectives. KW - Nuclear waste KW - Pre-disposal KW - Intermediate storage KW - Treatment KW - Monitoring PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-638480 DO - https://doi.org/10.1051/epjn/2025028 SN - 2491-9292 VL - 11 SP - 1 EP - 7 PB - EDP Sciences AN - OPUS4-63848 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Morichi, M. A1 - Fanchini, E. A1 - Bruggemann, C. A1 - Perot, B. A1 - Ricard, D. A1 - Niederleithinger, Ernst T1 - Developments and experiences of the CHANCE, MICADO and PREDIS projects in radioactive waste characterization N2 - Characterization is a very important step in dealing with materials and waste streams generated during the operational and decommissioning phases of nuclear installations, including nuclear power plants. Characterization allows differentiation between materials that can be released from regulatory control and those that require further treatment and conditioning to become a stable waste form suitable for future storage and final disposal according to its waste classification. Characterization is also needed in the pre-disposal stages of radioactive waste management to demonstrate compliance with the waste acceptance criteria of the facilities that will accept the different waste forms. This work will present the strategies developed and implemented by the three projects for in-depth and accurate waste characterization and investigation of the different radioactive waste packages considered. CHANCE, MICADO, and PREDIS will present their goals, the methods developed, the technologies used and the (preliminary) results contributing to the improvement of the safety and the data and information quality of the waste packages analyzed at the different stages of the waste management process. Special emphasis will also be given to complementary approaches highlighting the usability of the technologies, the accessibility of the data, and the problem-solving of the three projects within the European panorama. KW - Waste management KW - Radioactive waste KW - Waste chracterization PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-571872 DO - https://doi.org/10.1051/epjn/2022052 SN - 2491-9292 VL - 9 IS - 12 SP - 1 EP - 11 PB - EPJ Nuclear Sci. Technol. AN - OPUS4-57187 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -