TY - CONF A1 - Sridaran Venkat, Ramanan A1 - Stamm, Michael A1 - Wittmann, Jost A1 - Lauterbach, Helge A1 - Bleier, Michael 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-factor for the reliable, safe and efficient operation of wind turbines. 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. 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 are detectable during such an inspection. This deficiency is often compensated by thermography, a recognized method for detecting damages beneath the surface of an object. Thermography has been promoted and continuously developed at BAM for years. In the first part of this paper, the authors present the concept for a drone-based multisensory system that combines a thermal camera, a high-resolution visual camera and a 3D Laser scanner.The system provides a comprehensive view of the rotor blade samples internal and external conditions. In the second part of the paper, we present a lab-based demonstrator comprising an infrared camera and an RGB camera. We elaborate on the process for fusing the images comprising the calibration, image preprocessing and image registration. 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 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-625107 DO - https://doi.org/10.58286/29868 SN - 1435-4934 VL - 29 SP - 1 EP - 8 AN - OPUS4-62510 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stamm, Michael T1 - EvalTherm - Evaluation of passive Thermography for the inspection of wind turbine blades N2 - The EvalTherm project is presented. The concept of passive thermography on rotor blades as well as first results of field measurements are discussed. As this is an industry-related conference, the focus in this paper is on practical aspects that are of interest for industrial applications. T2 - AMI Wind Turbine Blade Manufacture conference 2021 CY - Cologne, Germany DA - 15.11.2021 KW - Windenergy KW - Thermography KW - Inspection KW - NDT PY - 2021 AN - OPUS4-53928 LA - eng 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - CONF A1 - Junker, Birgit A1 - Stamm, Michael T1 - No downtime thermographic rotor blade inspection N2 - In this presentation, the KI-VISIR Reference Dataset, created by the Bundesanstalt für Materialforschung und -prüfung (BAM) will be discussed. It includes thermographic and visual inspection data of 30 operational wind turbines. This dataset aims to support the maintenance and inspection of wind turbines, which are increasingly being built across Germany and Europe. The data is publicly available and helps in the development of digital methods for damage classification and inspection. T2 - AMI Wind Turbine Blades CY - Düsseldorf, Germany DA - 10.12.2024 KW - Thermography KW - Wind Turbine Blades KW - AI KW - KI-VISIR KW - NDT PY - 2024 AN - OPUS4-62498 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stamm, Michael T1 - Damage detection of wind turbine blades with thermographic inspection and AI-based classification N2 - In this presentation, the possibilities, limitations and challenges of thermographic rotor blade inspection will be discussed. Among other things, the data from the KI-VISIR reference data set will be discussed. This data was also used to train an AI-based image recognition system. T2 - WindEurope Technology Workshop 2024 CY - Dublin, Ireland DA - 10.06.2024 KW - Thermography KW - Wind Turbine Blades KW - AI KW - KI-VISIR KW - NDT PY - 2024 AN - OPUS4-62499 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 - 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 - CONF A1 - Lay, Vera A1 - Mielentz, Frank A1 - Prabhakara, Prathik A1 - Baensch, Franziska A1 - Johann, Sergej A1 - Hofmann, Detlef A1 - Sturm, Patrick A1 - Stamm, Michael A1 - Niederleithinger, Ernst T1 - Multi-sensory monitoring and ultrasound for quality assurance at underground sealing structures N2 - Within the safety concepts of underground disposal sites of nuclear waste, engineered barriers play an important role. As these sealing structures have high demands concerning integrity, we aim at advancing the available construction materials, monitoring, and inspection techniques within the project SealWasteSafe. A specifically developed alkali-activated material is compared to classical salt concrete. A comprehensive multi-sensory monitoring scheme is used at 150-340 l specimens to monitor setting and hardening of both materials. All sensors are demonstrated to resist the highly alkaline environments. Besides cabled and wireless temperature and humidity of the materials, strain variations using fibre optic sensors and acoustic emissions are recorded over periods of at least 28 days, partly for more than eight months. After hardening of the specimens, further nondestructive evaluations using ultrasonic echo and thermographic measurements are conducted. Preliminary results proof the suitability of the tested sensors and clearly highlight differences between the tested materials. Particularly, the newly developed alkali-activated material shows lower acoustic emission activity indicating less cracking activity. Additionally, unique ultrasonic methods will enable better images of potential internal objects and cracks at in-situ sealing structures. A largescale ultrasonic system is optimised to reliably detect objects at a depth exceeding 9 m while still obtaining a good resolution. Modelling studies show the potential of further increasing the distance between individual transducer arrays. Additionally, a new ultrasonic borehole probe using phased arrays allowing for beam focussing is constructed and tested. Laboratory measurements at a halfcylindrical concrete specimen coincide well with the previous modelling. In total, the presented safe materials, detailed monitoring approaches and ultrasonic quality assurance methods will help to obtain safe sealing structures within salt as a host rock. The concepts can partly be transferred to sealing structures in alternative host rocks and will also be valuable for non-nuclear waste repositories. T2 - NDE NucCon CY - Espoo, Finland DA - 25.01.2023 KW - SealWasteSafe KW - Engineered barriers KW - Monitoring KW - Embedded sensors KW - Ultrasonic imaging PY - 2023 SP - 2 EP - 10 AN - OPUS4-56928 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Chaudhuri, Somsubhro A1 - Krankenhagen, Rainer A1 - Lapšanská, Ivana A1 - Stamm, Michael T1 - WTB-IRT: Modelling and Measurement of Thermal Contrast in Wind Turbine Rotor Blades (WTBs) N2 - The rapid growth of wind energy infrastructure over the past two to three decades has led to an urgent need for advanced non-destructive testing (NDT) methods—both for newly installed wind turbine blades (WTBs) and for ageing components nearing the end of their service life. Among emerging techniques, passive infrared thermography (IRT) offers a promising solution by enabling contactless, time-efficient inspection based on naturally occurring thermal variations. The effectiveness of passive IRT depends on the presence of sufficient thermal contrast to distinguish surface features, subsurface structures, and defects. To better understand the possibility of obtaining such contrast in composite structures such as WTBs, a controlled study was carried out on a blade section exposed to programmed temperature transients in a climate chamber. Infrared measurements were recorded, and the thermal behaviour of the specimen was simulated using finite element models (FEM) in COMSOL Multiphysics 6.3. Although direct validation is limited by measurement uncertainties and transient effects, the comparison provides insight into the capabilities and limitations of FEM in replicating real-world thermal behaviour. This paper focuses specifically on the challenges related to the modelling approach. T2 - 18th International Workshop on Advanced Infrared Technology and Applications (AITA 2025) CY - Kobe, Japan DA - 15.09.2025 KW - Thermography KW - Wind energy KW - Wind turbine rotor blades KW - Windenergie Anlage Rotorblätter KW - FEA PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-642308 DO - https://doi.org/10.3390/proceedings2025129015 VL - 129 IS - 1 SP - 1 EP - 5 PB - MDPI CY - Basel AN - OPUS4-64230 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stamm, Michael T1 - The KI-VISIR Reference Dataset: A Compilation of Thermal and Visual Inspection Data for Quantifying Leading Edge Rain Erosion N2 - This presentation introduces thermography (thermal imaging) as a key method for non-destructive testing (NDT) of wind turbine rotor blades. By leveraging solar heating and aerodynamic effects, passive thermography detects internal defects, delaminations, and surface issues like leading edge erosion. We discuss field measurements, the role of AI/Machine Learning (LATODA) for automated defect classification, and its importance for improving O&M efficiency and lifetime extension in the wind energy sector. T2 - WindEurope Annual Event 2025 CY - Copenhagen, Denmark DA - 08.04.2025 KW - Thermography KW - Wind Turbine Blades KW - AI KW - NDT KW - KI-VISIR PY - 2025 AN - OPUS4-64721 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stamm, Michael T1 - Einführung thermografischer Methoden in die Ermüdungsprüfung unter Laborbedingungen sowie bei Ganzblatt-Rotorblattprüfungen N2 - Der Vortrag der Bundesanstalt für Materialforschung und -prüfung (BAM) stellt die Einführung und Anwendung thermografischer Methoden zur Ermüdungsprüfung und Ganzblatt-Rotorblattprüfung vor. Die BAM, tätig in Forschung, Prüfung und Beratung, trägt zur technischen Sicherheit bei und unterstützt die Energiewende. Die Abteilung 8.3 "Thermographic Methods" arbeitet an der Forschung, Entwicklung und Anwendung thermografischer Prüf- und Überwachungstechniken. Passive Thermografie ist eine bildgebende Messung der Oberflächentemperatur, die Informationen über das Innere von Bauteilen liefert. Durch Nutzung von Sonneneinstrahlung und Temperaturschwankungen können auch große Strukturen wie Rotorblätter geprüft werden. Thermische Inspektionen visualisieren Temperaturunterschiede, die durch Material-, Struktur-, Aerodynamik- und Oberflächeneigenschaften sowie Reibungswärme entstehen. Bei rotierenden Rotorblättern wird die Thermografie eingesetzt, um Strömungsphänomene (laminar/turbulent), Oberflächendefekte (z.B. Regen-Erosion) und innere Defekte zu erkennen. Ein Schlüsselprojekt ist die AI-gestützte Bildklassifizierung (LATODA) von über 1200 Roh-Infrarotbildern für die Mangeldetektion. Ziel ist die Entwicklung von zuverlässigen, automatisierten, robotergestützten Verfahren, um Schäden schnell zu erkennen und so Effizienzverluste (AEP-loss) zu vermeiden und die Lebensdauer von Windenergieanlagen zu verlängern. T2 - Mitgliederversammlung des BWE- Sachverständigenbeirates CY - Hannover, Germany DA - 5.9.2025 KW - Thermografie KW - Wind KW - Rotorblätter KW - Inspektion PY - 2025 AN - OPUS4-64719 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stamm, Michael T1 - Thermografische Ferninspektion von Windenergieanlagen im Betrieb –� Potenziale und Herausforderungen N2 - Rotorblätter zählen zu den kostenintensivsten Komponenten von Windenergieanlagen in Bezug auf Wartung und Ausfallzeiten. Mit der zunehmenden Blattlänge – aktuell bis zu 115 m – steigen auch die Anforderungen an effektive Inspektionsmethoden. Die Bundesanstalt für Materialforschung und -prüfung (BAM) entwickelt hierfür eine passive thermografische Ferninspektion vom Boden aus, die die klassische visuelle Prüfung durch Industriekletterer ergänzen oder perspektivisch ersetzen soll. Feldmessungen und Laborexperimente belegen das Potenzial dieser Technik, sowohl strömungsbedingte thermische Signaturen als auch strukturelle Anomalien innerhalb der Rotorblätter zu erfassen. Eine besondere Herausforderung liegt in der Trennung dieser überlagerten Effekte sowie in der eingeschränkten Kenntnis der inneren Blattstruktur aufgrund fehlender Designdaten. Um die Methode zur Marktreife zu führen, sind Fortschritte in der Bildverarbeitung, etwa durch eine patentierte Differenzbildung, erforderlich. Der Beitrag stellt die zugrunde liegende Messtechnik, Ergebnisse einer groß angelegten Feldstudie mit 30 Anlagen sowie die identifizierten physikalischen Einflussgrößen (Strömung, Struktur, Emissivität) vor und gibt einen Ausblick auf die nächsten Entwicklungsschritte. T2 - Thermo25 CY - Munich, Germany DA - 12.11.2025 KW - Thermography KW - Wind Turbine Blades KW - Wind KW - Rotorblätter PY - 2025 AN - OPUS4-64718 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chaudhuri, Somsubhro A1 - Krankenhagen, Rainer A1 - Lapšanská, Ivana A1 - Stamm, Michael T1 - Modeling Temperature Responses of a Wind Turbine Blade Section Under Climate Chamber Conditions – Part 1: Challenges for FEM Simulations N2 - The rapid expansion of wind energy infrastructure over the past 20–30 years has led up to a situation where advanced non‐destructive testing (NDT) technologies are the need‐of‐the‐hour, not only for new wind turbine blades (WTBs) that are being installed, but also for older infrastructure which is reaching their designed lifetime. NDT technologies that improve both the quality as well as reduce the time required for the inspection are sought after, and one such example is passive infrared thermography (IRT). For passive IRT to provide significant information/insight into the integrity of the WTB, there needs to exist certain thermal contrast to both visualize and distinguish between features in WTB. These features could be surface features, subsurface structure or defects. The temperature variations due to air temperature fluctuations and the sun assist (passively) to obtain the necessary thermal contrast. To better understand the thermal response of composite structures such as WTBs, a validation study was conducted using a WTB section subjected to controlled temperature transients within a climate chamber, without external irradiation. Infrared measurements were recorded using a thermographic camera, and the same specimen was modeled using finite element methods (FEM) in COMSOL Multiphysics. While a direct validation of the simulation is limited due to transient and unmeasured variables in the experimental data, qualitative comparison provides valuable insight into the applicability of FEM for predicting thermal behavior in passive IRT scenarios. This article represents the first part of a two‐part study, focusing on the FEM modeling approach and associated challenges. The second part will address the experimental investigation in more detail, with an emphasis on thermal contrast behavior under varied transient conditions. KW - Finite element modeling KW - Non- destructive testing KW - Passive infrared thermography KW - Thermal contrast KW - Wind turbine blades PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-655330 DO - https://doi.org/10.1002/we.70102 SN - 1095-4244 VL - 29 IS - 3 SP - 1 EP - 14 PB - Wiley AN - OPUS4-65533 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -