TY - CONF A1 - Hüllmann, Dino A1 - Neumann, Patrick P. A1 - Monroy, J. A1 - Lilienthal, A. J. T1 - A Realistic Remote Gas Sensor Model for Three-Dimensional Olfaction Simulations N2 - Remote gas sensors like those based on the Tunable Diode Laser Absorption Spectroscopy (TDLAS) enable mobile robots to scan huge areas for gas concentrations in reasonable time and are therefore well suited for tasks such as gas emission surveillance and environmental monitoring. A further advantage of remote sensors is that the gas distribution is not disturbed by the sensing platform itself if the measurements are carried out from a sufficient distance, which is particularly interesting when a rotary-wing platform is used. Since there is no possibility to obtain ground truth measurements of gas distributions, simulations are used to develop and evaluate suitable olfaction algorithms. For this purpose several models of in-situ gas sensors have been developed, but models of remote gas sensors are missing. In this paper we present two novel 3D ray-tracer-based TDLAS sensor models. While the first model simplifies the laser beam as a line, the second model takes the conical shape of the beam into account. Using a simulated gas plume, we compare the line model with the cone model in terms of accuracy and computational cost and show that the results generated by the cone model can differ significantly from those of the line model. T2 - 18th International Symposium on Olfaction and Electronic Nose (ISOEN) CY - Fukuoka, Japan DA - 26.05.2019 KW - Gas simulation KW - Remote gas sensor KW - TDLAS KW - Sensor model PY - 2019 AN - OPUS4-48245 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst A1 - Abraham, O. A1 - Larose, E. T1 - A review on ultrasonic monitoring of concrete: coda wave interferometry and beyond N2 - The propagation of ultrasonic waves in concrete is affected by its micro- and macro-structure, geometry and properties as well as external influences as stress, temperature or moisture. In addition, age and degradation have a strong influence. Therefore, Ultrasound has been used to monitor concrete samples and structures since decades. However, early applications using conventional techniques as time-of flight or changes in amplitudes have been limited to detect changes in a late stage close to serviceability or ultimate load states. Around 2000, several new, more sensitive techniques adopted from geophysics or other field of material sciences have been introduced to research in ultrasonic monitoring of concrete. The most discussed methodologies are coda wave interferometry, a technique which allows to detect very subtle changes from repeated ultrasonic measurements. Nonlinear acoustic techniques help to identify e. g. cracks even in an inhomogeneous background. Both techniques can be combined. This paper reviews methods and results achieved so far on the laboratory scale and with full scale models the directions for future research and application is given as well. T2 - QNDE 2019 CY - Portland, OR, USA DA - 14.07.2019 KW - Ultrasound KW - Coda wave interferometry KW - Concrete KW - Nonlinear KW - Monitoring PY - 2019 AN - OPUS4-48688 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waske, Anja T1 - A thermomagnetic generator for harvesting low-grade waste heat N2 - To date, there are only very few technologies available for the conversion of low temperature waste heat to electricity. In this talk, we first describe the principle of thermomagnetic generators. Then we focus on the impact of topology of the magnetic circuit within thermomagnetic generators. We demonstrate that the key operational parameters strongly depend on the genus, i.e. the number of holes within the magnetic circuit. T2 - Eingeladener Vortrag / Symposiumsorganisation und Vortrag CY - Uppsala, Sweden DA - 28.08.2019 KW - Energy harvesting KW - Magnetocaloric KW - Material Science KW - Non-Destructive testing PY - 2019 AN - OPUS4-50179 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waske, Anja A1 - Dzekan, D. A1 - Stork, A. A1 - Sellschopp, K. A1 - Berger, D. A1 - Nielsch, K. A1 - Fähler, S. T1 - A thermomagnetic generator with novel magnetic field topology N2 - To date, there are only very few technologies available for the conversion of low temperature waste heat to electricity. In this talk, we first describe the principle of thermomagnetic generators. Then we focus on the impact of topology of the magnetic circuit within thermomagnetic generators. We demonstrate that the key operational parameters strongly depend on the genus, i.e. the number of holes within the magnetic circuit. T2 - 2019 Joint MMM-Intermag Conference CY - Washington, DC, USA DA - 14.01.2019 KW - Energy harvesting KW - Magnetocaloric KW - Materials Science KW - Non-destructiv testing PY - 2019 AN - OPUS4-50152 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wasmer, Paul A1 - Bulling, Jannis A1 - Gravenkamp, Hauke A1 - Prager, Jens T1 - Acoustic-structure interaction in the scaled boundary finite element method for primsatic geometries N2 - Due to the short wavelength compared to the dimensions of the structure, the simulation of ultrasonic waves is still a challenging task. A numerical method well suited for this purpose is the semi-analytical Scaled Boundary Finite Element Method (SBFEM). When applying this method, only the boundary of a computational domain is discretized using finite elements, while the interior is described by an analytical ansatz. Hence, the number of degrees of freedom is reduced significantly compared to the classical Finite Element Method (FEM). In recent years, a particular formulation of the SBFEM for the simulation of ultrasonic guided waves was developed. The method constitutes an efficient algorithm for prismatic structures of arbitrary length, such as plates, pipes, or beams. Wave propagation phenomena in such structures can be modeled for isotropic and anisotropic inhomogeneous waveguides. Even though the method is an efficient tool for the simulation of guided waves in solid media, a reliable model for the simulation of acoustic wave propagation in fluids as well as acoustic-structure interaction in terms of SBFEM is still missing. In principle, the fluid can be described by a displacement-based formulation and thus be implemented in existing SBFEM algorithms for solid bodies. However, due to the discretization with classical finite elements, spurious modes occur, which cannot be separated from the physical modes straightforwardly. The spurious modes can be suppressed using a penalty parameter. Although very accurate results were achieved for some problems, this procedure has been proven unreliable for certain cases. For this reason, we propose a different approach in this contribution. We employ a pressure model to simulate the acoustic behavior of fluids. The implementation of the pressure model results in a higher effort due to the necessity of incorporating coupling terms, but it presents a stable alternative without spurious modes. The accuracy of the method is demonstrated in comparison with analytical solutions and results obtained using the FEM. T2 - GACM 2019 CY - Kassel, Germany DA - 28.08.2019 KW - Scaled Boundary Finite Element Method KW - Guided Waves KW - Acoustic-structure interaction PY - 2019 AN - OPUS4-48846 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krankenhagen, Rainer T1 - Active IR Thermography N2 - This is an overview about physics and principles of active thermography.The generation and detection of thermal contrasts is described. Two applications are explained more in detail: a large mural at a building wall heated by sun and crack detection supported by additional heating. T2 - NDT&E Advanced Training Workshop 2019 CY - Berlin, Germany DA - 12.06.2019 KW - NDT KW - Thermography KW - Civil engineering PY - 2019 AN - OPUS4-49790 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Magkos, Sotirios T1 - Advanced algorithms for image reconstruction in Computed Tomography N2 - This PhD project is part of the Marie Skłodowska-Curie International Training Network MUMMERING. The overarching goal of MUMMERING is the creation of a research tool that exploits the wealth of 3D imaging modalities applied in materials engineering. The focus of this work is advanced reconstruction algorithms. The primary objective is the development and implementation of the DIRECTT algorithm. Due to restrictions introduced by the sample or the imaging setup during a measurement, it is not always possible to acquire data that fulfil the Nyquist sampling criterion. The DIRECTT algorithm is intended to produce reconstructions of superior quality for such cases of limited data sets, compared to those of other available algorithms, such as algebraic iterative ones. Although DIRECTT has been developed primarily for the reconstruction of volumes from data acquired by an X-ray Computed Tomography scanner, it can also be applied to the different modalities, such as laminography. The talk describes the reconstruction principle of DIRECTT. Furthermore, reconstructions of measured data are presented and compared to reconstructions produced by other established algorithms. T2 - Doktorandenseminar CY - BAM Berlin, Germany DA - 16.12.2019 KW - Computed Tomography KW - Reconstruction KW - DIRECTT PY - 2019 AN - OPUS4-50066 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gaal, Mate A1 - Kotschate, Daniel A1 - Bente, Klaas T1 - Advances in air-coupled ultrasonic transducers for non-destructive testing N2 - Conventional ultrasonic testing involves the application of a fluid couplant for impedance matching. Increasing use of lightweight structures, composite materials and adhesive joints mostly in aerospace and automotive industry created an increasing interest in air-coupled ultrasonic testing methods, to protect sensitive surfaces and simplify maintenance. Commercially available air-coupled transducers consist of a piezocomposite material and matching layers to reduce the impedance mismatch between the transducer and air. This contribution is an overview of innovative approaches using new piezoelectric materials and other physical principles to transmit and receive an ultrasonic pulse in air. Capacitive and piezoelectric micromachined ultrasonic transducers (CMUTs and PMUTs) produce high pressure levels, but they exhibit a very narrow bandwidth. Optical laser-based methods for transmitting and receiving ultrasound promise a higher bandwidth, but do not achieve the same sensitivity as conventional air-coupled transducers. Ferroelectrets are charged cellular polymers exhibiting piezoelectric properties, having a very small acoustic impedance well matched to air. Ferroelectret transducers achieve about the same bandwidth as the most broadband conventional air-coupled transducers, having a higher sensitivity. Thermoacoustic transducers use heat to initiate an acoustic wave, acting as transmitters in ultrasonic range. Thermoacoustic transducers enable excitation of extremely broadband pulses while producing high pressure levels, which opens new possibilities for advanced signal processing. The newest member of the family of air-coupled ultrasonic transmitters is the plasma-based transducer, using both the thermoacoustic effect and the movements of the ions (so called ionic wind) to create acoustic waves. T2 - International Congress on Ultrasonics CY - Bruges, Belgium DA - 03.09.2019 KW - Air-coupled transducers KW - Non-destructive testing KW - Ferroelectret KW - Thermoacoustics KW - Plasma acoustics PY - 2019 AN - OPUS4-48963 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Evans, Alexander A1 - Mohr, Gunther A1 - Hilgenberg, Kai A1 - Straße, Anne A1 - Gumenyuk, Andrey A1 - Winterkorn, René A1 - Pittner, Andreas A1 - Sommer, Konstantin A1 - Bettge, Dirk A1 - Kranzmann, Axel A1 - Nolze, Gert A1 - Avila, Luis A1 - Rehmer, Birgit A1 - Charmi, Amir A1 - Falkenberg, Rainer A1 - Skrotzki, Birgit A1 - Werner, Tiago A1 - Madia, Mauro A1 - Zerbst, Uwe A1 - Ulbricht, Alexander A1 - Sprengel, Maximilian A1 - Kromm, Arne A1 - Thiede, Tobias A1 - Bruno, Giovanni T1 - Ageing in additively manufactured metallic components: from powder to mechanical failure” an overview of the project agil N2 - An overview of the BAM funed Focus Area Materials Project "AGIL" will be presented. AGIL focussed on the stdiy of the ageing characteristics of additively manufactured austenitic stainless steel with a "powder to mechanical failure" Approach. Recent Highlights are presented and a perspective for future studies. T2 - Workshop on Additive Manufacturing CY - BAM, Berlin, Germany DA - 13.05.2019 KW - Residual stress KW - Additive Manufacturing KW - Non-destructive testing KW - Microstructure characterisation KW - Tensile testing KW - Fatigue KW - Crystal Plasticity Modelling KW - Crack propagation PY - 2019 AN - OPUS4-49823 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Vössing, Konrad A1 - Gaal, Mate A1 - Niederleithinger, Ernst T1 - Air-coupled ferroelectret ultrasonic transducers for nondestructive testing of wood in through transmission and reflection mode N2 - The necessity and demand for nondestructive testing of wood-based materials which can automatically scan huge areas of wood is increasing. Air-coupled ultrasound (ACU) is used to detect defects and damage without altering the structure permanently. Using through transmission it is possible to detect even small holes and missing adhesive. If only one side of an object is accessible the reflection mode is preferred at the expense of a reduced resolution and penetration depth. Novel ferroelectret transducers with a high signal-to-noise ratio (SNR) enable a high-precision structure recognition. The transducers made of cellular polypropylene (PP) are quite suitable for ACU testing due to their extremely low Young’s modulus and low density which result in a favorable acoustic impedance for the transmission of ultrasonic waves between the transducer and air. Thus, defects such as delamination, rot, and cracks can be detected. Promising results were obtained under laboratory conditions with frequencies from 90 kHz to 200 kHz. The advantage of these ACU transducers is that they do not require contact to the sample, are accurate, and cost effective. Ultrasonic quality assurance for wood is an important attempt to increase the acceptance of wooden structures and towards sustainability in civil engineering in general. T2 - International Conference on Sustainable Materials, Systems and Structures CY - Rovinj, Croatia DA - 20.03.2019 KW - Air-coupled ultrasound KW - Cellular polypropylene KW - Wood KW - Nondestructive Testing KW - Defect detection PY - 2019 AN - OPUS4-47683 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gaal, Mate A1 - Bente, Klaas A1 - Hufschläger, Daniel T1 - Air-coupled ultrasonic sensors N2 - We present an overview of air-coupled ultrasonic transducers. T2 - Workshop BAM-IWF CY - Berlin, Germany DA - 25.11.2019 KW - Air-coupled transducers KW - Ferroelectret KW - Thermoacoustics KW - Plasma PY - 2019 AN - OPUS4-49806 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zscherpel, Uwe A1 - Ewert, Uwe T1 - Aktuelle Entwicklungen in der Standardisierung N2 - In den letzten zwei Jahren wurden 11 neue Standards/Standardrevisionen zur RT veröffentlicht (ohne Strahlenschutz) und 5 werden dafür gestrichen. Es wird über die neuen Anforderungen ausgewählter Normen bzw. Normrevisionen informiert und insbesondere auch über die veränderten Parameter, die bei Prüfpraxis und bei der Klassifizierung zu berücksichtigen sind. Das wichtigste Projekt ist die Revision der DIN EN ISO 17636-1, -2, RT von Schweißverbindungen, in ISO TC 44 SC 5 WG 1. Die Standards zur Schweißnahtprüfung in der Kerntechnik, DIN 25435, wurden ins Englische übertragen und bei ISO TC 85 SC 6 bearbeitet. Hauptaktivität bei ASTM ist gegenwärtig die Überarbeitung der CT-Standards und die Berücksichtigung der Anforderungen an das dimensionelle Messen. Der Guide ASTM E 1441 zur Bestimmung von MTF, Kontrast-Detail-Funktion (CDF) und Kontrast-Diskrimination-Diagramm (CDD) wird revidiert. E 2445 zur CR Long Term Stability wird ebenfalls revidiert. Die Revision soll auch in die ISO 16371-1 eingehen. Dazu ist ein Round Robin-Test geplant. Auch die Standards zur Durchstrahlungsprüfung auf Korrosion und Ablagerungen in Rohren mit Röntgen- und Gammastrahlen (EN 16407-1, -2, 2014) wurden revidiert. Diese Revision wurde als DIN EN ISO 20769-1, -2 2018 veröffentlicht und EN 16407 wird zurückgezogen. Die Revision der Standards EN 12543 und EN 12679 zur Messung der Brennfleckgröße und der Strahlergröße ist mit Verzögerung in Überarbeitung, um die digitalen Detektoren und Messmöglichkeiten mit Bildverarbeitungsprogrammen zu berücksichtigen. Ein Entwurf zur Messung der Brennfleckgröße von nano-Fokusröhren wird derzeit vom Europäischen Metrologie-Programm EMPIR gefördert. Zur radiographischen Gussteilprüfung wurde der Standard EN 12681 revidiert und 2018 veröffentlicht. Er wurde um Zulässigkeitsgrenzen erweitert und die digitale Radiographie wurde in Teil 2 berücksichtigt. T2 - 18. Seminar der DGZfP zu aktuellen Fragen der Durchstrahlungsprüfung und des Strahlenschutzes CY - Kassel, Germany DA - 28.03.2019 KW - Radiographische Prüfung KW - Standardisierung bei DIN, CEN und ISO KW - DGZfP-Richtlinien PY - 2019 AN - OPUS4-50529 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heckel, Thomas T1 - Akustische und elektromagnetische Prüfverfahren für verlegte Eisenbahnschienen N2 - In diesem Vortrag werden die aktuellen Techniken für die angewandte mechanisierte Schienenprüfung dargestellt und Perspektiven für die Zukunft der handgeführten und fahrzeuggeführten Prüftechnik aufgezeigt. Insbesondere wird hier die bildhafte Darstellung, der zusätzliche Nutzen von Arraysensoren sowie die Möglichkeiten der Simulation von Schienenfehlern vorgestellt. T2 - ZfP-Prüfertag 2019 im RB Südost CY - Halle, Germany DA - 13.11.2019 KW - Arraysensoren KW - Mechanisierte Schienenprüfung KW - Ultraschall KW - Wirbelstrom KW - Simulation PY - 2019 AN - OPUS4-49687 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lugovtsova, Yevgeniya A1 - Bulling, Jannis A1 - Prager, Jens T1 - Analyse der Ausbreitung geführter Wellen in einem Mehrschichtverbund zur Zustandsüberwachung von Composite-Druckbehältern N2 - Composite-Druckbehälter werden für Speicherung und Transport von Gasen unter hohem Druck verwendet. Durch die gewichtssparende Struktur, die aus einem dünnwandigem Metallgefäß und Faserverbundwerkstoff-Ummantelung besteht, sind solche Behälter insbesondere für die Luftfahrt- und Automobilindustrie interessant, z.B. als Wasserstoffspeicher. Die Druckprüfung ist ein konventioneller Test, um die Integrität von Metalldruckbehältern zu bewerten. Im Falle des Composite-Druckbehälters könnte eine solche Prüfung jedoch den Faserverbundwerkstoff überbeanspruchen und somit die verbleibende Lebensdauer der getesteten Komponente verringern. Infolgedessen ist es notwendig, Verfahren zur zerstörungsfreien Prüfung und möglicherweise zur Zustandsüberwachung von Composite-Druckbehältern zu entwickeln. Unser Ansatz verwendet geführte Ultraschallwellen und hat das Potenzial, kritische Schäden wie Risse im Metall und Faserbrüche und Matrixrisse in Faserverbundwerkstoff zu detektieren. In diesem Beitrag wurde die Scaled Boundary Finite Elemente Methode benutzt, um die multimodale, geführte Wellenausbreitung in einem Mehrschichtverbund, der aus Metall und Kohlenfaserverbund entsteht, zu analysieren. Das Verfahren ermöglicht die Identifizierung geeigneter Wellenmoden und die Analyse ihrer Interaktion mit verschiedenen Schäden. Diese Kenntnisse sollen für die Entwicklung von Verfahren zur Zustandsüberwachung von Composite-Druckbehältern angewendet werden. T2 - 22. Kolloquium Schallemission und 3. Anwenderseminar Zustandsüberwachung mit geführten Wellen CY - Karlsruhe, Germany DA - 27.03.2019 KW - Wasserstoffspeicher KW - Automobilindustrie KW - SBFEM KW - Faserverbundwerkstoff KW - Ultraschallwellen PY - 2019 AN - OPUS4-47689 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lugovtsova, Yevgeniya A1 - Johannesmann, S. A1 - Henning, B. A1 - Prager, Jens T1 - Analysis of Lamb wave mode repulsion and its implications to the characterisation of adhesive bonding strength N2 - Lamb waves are widely used for non-destructive evaluation of material parameters as well as for detection of defects. Another application of Lamb waves is quality control of adhesive joints. Researchers are currently investigating shear horizontal and zero-group velocity modes for characterisation of the adhesive bonding strength. In a new approach, Lamb wave mode repulsion is used to obtain the coupling strength between different layers to characterise the adhesive bonding strength. The modes of the individual layers become coupled in the multilayered systems forming particular regions, the so-called mode repulsion regions. This study investigates these modes and their interaction in two-layered plate-like structures with varying coupling strength both numerically, with the Scaled Boundary FEM, and experimentally. T2 - International Congress on Ultrasonics CY - Bruges, Belgium DA - 03.09.2019 KW - Lamb waves KW - Multi-layered system KW - Adhesive joint KW - Mechanical strength KW - Scaled Boundary FEM PY - 2019 AN - OPUS4-48910 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zscherpel, Uwe A1 - Ewert, Uwe T1 - Annual report of sub commission V-A “Radiography-based weld inspection” N2 - Report on the annual activities of IIW commission V, Sub-Commission V-A "Radiography based weld inspection" chaired by Uwe Zscherpel, BAM Berlin T2 - 72. Annual Assembly of the International Institute of Welding 2019 CY - Bratislava, Slovakia DA - 07.07.2019 KW - International Institute of Welding KW - Sub-Commission V-A KW - Radiography based weld inspection PY - 2019 AN - OPUS4-50533 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tiebe, Carlo A1 - Majewski, J. T1 - Ansprechzeiten von Wasserstoff-Sensoren N2 - Die Effizienz von Gassensoren zur sicheren Verwendung von Wasserstoff hängt wesentlich von der Reaktion des Sensors auf eine Änderung der Wasserstoffkonzentration ab. Daher wurde die Ansprechzeit von fünf im Handel erhältlichen Wasserstoffsensoren unterschiedlichen Messprinzips bestimmt. Experimente haben gezeigt, dass alle Sensoren die Anforderungen der Norm ISO 26142 übertreffen; es wurden Ansprechzeiten im Bereich (t90-Zeiten) von 2 s bis 16 s ermittelt. Die Ergebnisse können mit Exponential- oder Sigmoidalfunktionen approximiert werden. Es kann gezeigt werden, dass die Ergebnisse zum transienten Verhalten sowohl von den Betriebsparametern der Sensoren und Prüfverfahren als auch von den experimentellen Bedingungen wie Gaswechselrate sowie Konzentrationssprung abhängen. T2 - 7. HYPOS-Dialog - Innovative Wasserstoffsensorik CY - Halle (Saale), Germany DA - 19.06.2019 KW - Wasserstoffsensor KW - Ansprechzeit KW - t90-Zeit KW - Prüfverfahren PY - 2019 AN - OPUS4-48397 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Büttner, C. A1 - Niederleithinger, Ernst A1 - Buske, S. A1 - Friedrich, C. T1 - Anwendung seismischer Abbildungsverfahren auf Ultraschallecho-Daten von Verschlussbauwerken unter Tage N2 - Ein Endlager für radioaktive Abfälle muss auf Dauer vor dem Eindringen von Wasser geschützt werden. Aus diesem Grund errichtete die Bundesgesellschaft für Endlagerung (BGE) ein Verschlussbauwerk als InSitu Versuch im Endlager Morsleben. Hierfür wurde eine bergmännische Auffahrung mit Salzbeton verfüllt. Zusätzliche in regelmäßigen Abständen eingebaute Trennbleche sollen der Ausbreitung eventueller Risse entgegenwirken. Das Versuchsobjekt wurde mit Ultraschallmessungen bezüglich der Lage und Orientierung möglicher Risse untersucht. Diese Messungen wurden an der Stirnfläche des Salzbetonkörpers durchgeführt. Für die Datenakquisition fand ein neuartiges Messsystem Anwendung, mit welchem ein seismisches Akquisitionsschema realisiert werden kann. Dieses setzt sich aus mehreren Prüfköpfen zusammen, welche sowohl als Sender als auch als Empfänger fungieren. Somit lassen sich auch größere Sender-Empfänger-Abstände realisieren. Vor der Bearbeitung der realen Messdaten wurde ein realitätsnahes synthetisches Modell erstellt, mit welchem die Abbildung eines Risses, eines eingebauten Monitoring-Instruments sowie des ersten Trennbleches in einer Tiefe von 8 m untersucht wurden. Die generierten synthetischen Daten wurden nach minimaler Preprozessierung mittels Kirchhoff-Prestack-Tiefenmigration sowie Reverse Time Migration (RTM) in Tiefensektionen umgewandelt. Insbesondere bei der Abbildung steilstehender Reflektoren lieferte die RTM hier ein besseres Ergebnis. Im Anschluss wurden reale Messdaten in der gleichen Weise bearbeitet. Zusätzlich wurden die Ergebnisse mit denen der Synthetic-Aperture-Focusing-Technique (SAFT) verglichen. Dieses Verfahren ist der Kirchhoff-Migration sehr ähnlich und findet in der zerstörungsfreien Werkstoffprüfung routinemäßig Anwendung. Es stellte sich heraus, dass der RTM Algorithmus in einigen Fällen ein realitätsnäheres Abbild liefert. Die Resultate von Kirchhoff-Migrationund SAFT-Rekonstruktion sind hingegen sehr ähnlich. Alle Verfahren lokalisierten in gleicher Weise Risse in verschiedenen Tiefenlagen, welche hauptsächlich oberflächenparallel orientiert sind. Diese werden auch von Bohrungen bestätigt. Besonders herauszustellen ist die deutliche Abbildung des Trennbleches in großer Tiefe, was bisher noch nicht eindeutig gelungen war. T2 - Jahrestagung der Deutschen geophysikalischen Gesellschaft CY - Brunswick, Germany DA - 03.03.2019 KW - Ultraschall KW - Verschlussbauwerk KW - Endlagerung KW - RTM KW - Kirchhoff PY - 2019 AN - OPUS4-47705 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waske, Anja T1 - Anwendungsaspekte magnetischer Funktionsmaterialien: Untersuchungen mit Computertomographie N2 - In diesem Vortrag wird am Beispiel magnetischer Werkstoffe zur Energiewandlung gezeigt, wie röntgentomographische Untersuchungen zur Strukturaufklärung in Kompositen und Massivproben beitragen können. Die Bauteile werden zerstörungsfrei geprüft, um Risse, Poren und andere Defekte und ihren Einfluss auf die funktionellen Eigenschaften dreidimensional und rechtzeitig im Lebenszyklus des Werkstoffs zu charakterisieren. Kombiniert man Mikrotomographie mit anderen Methoden der magnetischen Werkstoffcharakterisierung, lassen sich einzigartige Aussagen über den Aufbau und die funktionellen Eigenschaften treffen. T2 - Werkstoffwoche CY - Dresden, Germany DA - 18.09.2019 KW - X-Ray Imaging KW - Additive Manufacturing KW - Magnetocaloric KW - Material Science KW - Non-Destructive testing PY - 2019 AN - OPUS4-50175 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Evsevleev, Sergei A1 - Paciornik, Sidnei A1 - Gollwitzer, Christian A1 - Bruno, Giovanni T1 - Application of deep learning to the segmentation of synchrotron X-ray tomography data of multiphase metal matrix composites N2 - The 3D microstructure of an Al alloy matrix composite with two ceramic reinforcements was investigated by synchrotron X-ray tomography. A deep learning algorithm was used for the segmentation of four different phases. We show that convolutional networks with the U-Net architecture are able to solve complex segmentation tasks with small amount of training data. T2 - International Conference on Tomography of Materials & Structures CY - Cairns, Australia DA - 22.07.2019 KW - Synchrotron X-ray tomography KW - Deep learning KW - Segmentation KW - Metal matrix composite PY - 2019 AN - OPUS4-48606 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Oesch, Tyler A1 - Niederleithinger, Ernst A1 - Mielentz, Frank A1 - Effner, Ute A1 - Behrens, Matthias A1 - Friedrich, C. A1 - Mauke, R. A1 - Büttner, C. T1 - Application of ultrasonic techniques for quality assurance of salt concrete engineered barriers: Shape, cracks and delamination N2 - The closure of underground nuclear waste disposal facilities requires reliable gas- and water-tight engineered barriers. In Germany, barriers made from salt concrete have been evaluated in full scale. While the barriers seem to fulfill the requirements regarding permeability, some unexpected cracks have been detected at the surface and at depth. In cooperation between the Federal Company for Radioactive Waste Disposal (BGE) and the Federal Institute for Materials Research and Testing (BAM), several experiments have been carried out to evaluate the applicability for ultrasonic measurements in crack detection and general quality assurance. Both commercial instruments and specially developed devices have been tested on site. Using commercial ultrasonic echo devices designed for concrete inspection it was possible to detect cracks and objects in salt concrete up to a depth of 2 m. The check for delamination in shotcrete is another field of application. A unique device available at BAM, the wide aperture, deep penetration instrument LAUS, was able to locate cracks and objects up to a depth of 8 m so far, which is thought to be a record for ultrasonic echo measurements in concrete. Adapted imaging procedures, partly adopted from geophysics, helped to reveal 3D structure at depth. In addition, we have developed ultrasonic probes to be deployed in boreholes, currently at up to 20 m depth. They can collect information on cracks and other features in a radius of about 1.5 m around the borehole in the current version and might be used in echo or transmission mode. Evaluation experiments have been performed at an experimental barrier at the ERAM site in Morsleben, Germany. The results showed several empty and injected cracks as well as built-in instrumentation. The results have been verified using borehole endoscopy as well as core examination and will be used to set up a reliable quality assurance system for engineered barriers. All instruments are based on ultrasonic shear wave transducers with a frequency range between 25 kHz and 100 kHz. Current research focuses on the improvement of the hardware (e. g. optimization of array characteristics) and imaging techniques such as Reverse Time Migration, both aiming at the improvement of depth of penetration, resolution and probability of detection. T2 - 2nd International Conference on Monitoring in Geological Disposal of Radioactive Waste CY - Paris, France DA - 09.04.2019 KW - Morsleben Repository (ERAM) KW - Engineered Barrier System (EBS) KW - Large Aperture Ultrasonic System (LAUS) KW - Ultrasonic-Echo Borehole Probe KW - Reverse Time Migration (RTM) PY - 2019 AN - OPUS4-47781 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst A1 - Effner, Ute A1 - Behrens, Matthias A1 - Smith, Sean A1 - Büttner, C. A1 - Friedrich, C. A1 - Mauke, R. T1 - Application of ultrasonic techniques for quality assurance of salt concrete engineered barriers: Shape, cracks and delamination N2 - The closure of underground nuclear waste disposal facilities requires reliable gas- and watertight engineered barriers. In Germany, barriers made from salt concrete have been evaluated in full scale. While the barriers seem to fulfill the requirements regarding permeability, some unexpected cracks have been detected at the surface and at depth. In cooperation between the Federal Company for Radioactive Waste Disposal (BGE) and the Federal Institute for Materials Research and Testing (BAM), several experiments have been carried out to evaluate the applicability for ultrasonic measurements in crack detection and general quality assurance. Both commercial instruments and specially developed devices have been tested on site. Using commercial ultrasonic echo devices designed for concrete inspection it was possible to detect cracks and object in salt concrete up to a depth of 2 m. The check for delamination in shotcrete is another field of application. A unique device available at BAM, the wide aperture, deep penetration instrument LAUS, was able to locate cracks and objects up to a depth of 8 m so far, which is thought to be a record for ultrasonic echo measurements in concrete. Adapted imaging procedures, partly adopted from geophysics, helped to reveal 3D structure at depth. In addition, we have developed ultrasonic probes to be deployed in boreholes, currently at up to 20 m depth. They can collect information on cracks and other features in a radius of about 1.5 m around the borehole in the current version and might be used in echo or transmission mode. Evaluation experiments have been performed at an experimental barrier at the ERAM site in Morsleben, Germany. The results showed several empty and injected cracks as well as built in instrumentation. The results have been verified using borehole endoscopy as well as core examination and will be used to set up a reliable quality assurance system for engineered barriers. All instruments are based on ultrasonic shear wave transducers with a frequency range between 25 kHz and 100 kHz. Current research focuses on the improvement of the hardware (e. g. optimization of array characteristics) and imaging techniques as Reverse Time Migration, both aiming at the improvement of depth of penetration, resolution and probability of detection. T2 - Modern 2020, 2nd International Conference about Monitoring in Geological Disposal of Radioactive Wast CY - Paris, France DA - 09.04.2019 KW - REverse Time Migration (RTM) KW - Engineered Barrier System (EBS) KW - Non-Destructive Testing KW - Ultrasonic Echo KW - Large Aperture Ultrasonic System (LAUS) KW - Synthetic Aperture Focusing Technique (SAFT) PY - 2019 AN - OPUS4-48974 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Jan P. A1 - Dell'Avvocato, G. A1 - Krankenhagen, Rainer T1 - Applying a two-layer quadrupole model for quantitative thermography at overload-induced delaminations in GFRP N2 - The applicability of 1D-quadrupole-model on the depth estimation of overload-induced delaminations is tested in this contribution. While classical 1D-methods like Pulsed Phase Transformation and Thermographic Signal Reconstruction determine the depth of a defect by one parameter, a two-layer quadrupole model provides two parameters: depth and thermal resistance. In addition, the convectional losses at the surfaces may be considered. The defect investigated is a large-scale delamination in glass fibre reinforced polymer generated by tension overload. T2 - Advanced Infrared Technology & Applications (AITA) CY - Florenz, Italy DA - 16.9.2019 KW - Aktive Thermographie KW - Nicht-lineare Regression KW - 1D-Simulation KW - GFK PY - 2019 AN - OPUS4-49133 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Genath, A. A1 - Hofmann, Michael A1 - Tiebe, Carlo A1 - Einspanier, R. T1 - Auf dem Weg zum Monitoring der Ameisensäurekonzentration in der Bienenstock-Luft mit einem Multigassensorsystem N2 - Die Varroose gilt weltweit als eine der bedeutendsten Erkrankungen der westlichen Honigbiene, Apis mellifera. Verursacht wird sie durch den Ektoparasiten Varroa destructor, der durch Saugen der Hämolymphe und Virenübertragung sowohl die Bienenbrut als auch die adulten Individuen schädigt. Ohne imkerliche Unterstützung gehen betroffene Bienenvölker in der Regel innerhalb von drei Jahren ein. Als bewährte, häufige Behandlung wird flächendeckend 60%ige Ameisensäure (AS) - im Bienenstock appliziert über verschiedene Verdampfungssysteme - eingesetzt. Sie wirkt als einziger zugelassener Stoff gegen die Varroamilbe auch in die verdeckelte Brut hinein und birgt kein Risiko der Resistenzentwicklung. Allerdings ist das therapeutische Fenster, der Bereich zwischen Milbenabtötung und Bienenschädigung, relativ schmal und die tatsächliche AS-Konzentration im Bienenstock stark abhängig von äußeren Einflussfaktoren, wie Temperatur, Luftfeuchte oder Applikationsart. Eine Bestimmung der exakten AS-Konzentration im Bienenstock ist also notwendig, um einerseits das Wirkungsoptimum zu bestimmen und andererseits bei Übersteigen der Maximalkonzentrationen mit Folge-Schädigung der Bienen, ein rechtzeitiges Eingreifen der Imker zu ermöglichen. T2 - 6. HSN-Fachsymposium „Innovative Sensorik, verteilte Sensorsysteme, neue Technologien und Anwendungsfelder“ CY - Karlsruhe, Germany DA - 06.11.2019 KW - Biene KW - Apis mellifera KW - Varroa destructor KW - Ameisensäure KW - Multigassensorik PY - 2019 AN - OPUS4-49606 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni A1 - Evans, Alexander T1 - Avoid living dangerously: non-destructive characterization of AM parts from powder to end-of-life N2 - The freeform and the revolutionary design possibilities offered by additive manufacturing have skyrocketed the amount of optimization studies in the realm of engineering, and metallic additive manufactured parts are becoming a reality in industry. Not surprisingly, this has not been paralleled by a similar enthusiastic wave in the realm of materials science, and still very little is known about AM materials properties. This has the consequence that, typically, conventional materials properties are still used in design and even in simulations. lt is necessary to dig a lot deeper than at present, in order to understand these new materials classes, and in particular their microstructure and their intemal stresses, largely different from their cast or wrought companions. T2 - ISAM Konferenz 2019 CY - Dresden, Germany DA - 29.01.2019 KW - Computed Tomography KW - Microstructure KW - Metals KW - Additive Manufacturing PY - 2019 AN - OPUS4-47331 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kupsch, Andreas A1 - Schob, D. A1 - Léonard, Fabien A1 - Müller, Bernd R. A1 - Sagradov, I. A1 - Roszak, R. A1 - Sparr, H. A1 - Franke, R. A1 - Ziegenhorn, M. A1 - Bruno, Giovanni T1 - Bestimmung der Mikrostruktur und Simulation des Schädigungs-verhaltens von lasergesintertem Polyamid 12 unter statischer Zugbelastung N2 - Um das Material- und Schädigungsverhalten von additiv gefertigtem Polyamid 12 (PA12) unter quasistatischer Belastung zu charakterisieren, wurden mechanische Tests und Experimente zur Bestimmung der Mikrostruktur durchgeführt. Die Proben wurden nach dem Prinzip des Selektiven Lasersinterns (SLS) hergestellt. Unter quasistatischer Belastung mit Haltezeiten ergab sich ein viskoplastisches Materialverhalten. Im Zugversuch wurde eine maximale Zugfestigkeit von 40.6 MPa und eine Bruchdehnung von 7.4% beobachtet. Mittels Digitaler Bildkorrelation (DIC) wurde die Ausbildung von Scherbändern während des Zugs nachgewiesen. Mittels Röntgenrefraktion wurde eine Erhöhung von inneren Oberflächen beobachtet, die senkrecht zur Zugrichtung orientiert sind. Die Analyse der Gesamtporosität aus Computertomographie-Messungen ergab keine Änderung infolge der Zugbelastung. Jedoch wurde eine bimodale Porengrößenverteilung und eine steigende Sphärizität festgestellt. Das Materialverhalten wurde mit den Ergebnissen des Zugversuchs nach dem Chaboche Modell [3] in sehr guter Übereinstimmung simuliert. Allerdings gestattet dieses Modell nicht, das Bruchverhalten einzuschließen. Daher wurde zur Simulation des Schädigungsverhaltens das Modell gemäß dem Ansatz von Gurson, Tvergaard und Needleman unter Berücksichtigung der mikrostrukturellen Parameter erweitert. Während das Chaboche Modell eine homogene Spannungsverteilung generiert, zeigt das erweiterte Modell die Ausbildung von Scher¬bändern und die korrekte Bruchdehnung. Der Schwerpunkt des Vortrages liegt auf den Röntgenverfahren zur experimentellen Bestimmung der Mikrostruktur. T2 - DGM-Symposium "Additive Fertigung in der Kunststoffindustrie" CY - Würzburg, Germany DA - 14.11.2019 KW - Additive Fertigung KW - Selektives Lasersintern KW - Polyamid 12 KW - Röntgenrefraktion KW - Computertomographie KW - Porosität PY - 2019 AN - OPUS4-49707 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Burgholzer, P. A1 - Ziegler, Mathias A1 - Thiel, Erik A1 - Ahmadi, Samim A1 - Gruber, J. A1 - Mayr, G. A1 - Hendorfer, G. A1 - Haltmeier, M. T1 - Blind structured illumination as excitation for super-resolution photothermal radiometry N2 - Photothermal radiometry with an infrared camera allows the contactless temperature measurement of multiple surface pixels simultaneously. A short light pulse heats the sample. The heat propagates through the sample by diffusion and the corresponding temperature increase is measured at the samples surface by an infrared camera. The main drawback in radiometric imaging is the loss of the spatial resolution with increasing depth due to heat diffusion, which results in blurred images for deeper lying structures. We circumvent this information loss due to the diffusion process by using blind structured illumination, combined with a non-linear joint sparsity reconstruction algorithm. T2 - Fifth NDTonAIR Training Event: Thermography Workshop CY - Linz, Austria DA - 13.02.2019 KW - Super resolution KW - Thermography KW - Laser Thermography KW - Compressed Sensing KW - NDT PY - 2019 AN - OPUS4-49912 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bulletti, A. A1 - Capineri, L. A1 - Lugovtsova, Yevgeniya A1 - Prager, Jens T1 - Charachterization of piezopolymer interdigital transducer's vibrational modes N2 - Lamb waves are widely used for monitoring the health of structures made of laminated materials (metals, composites). Piezoelectric ultrasonic transducers transmit and receive acoustic guided waves that interact with the elastic properties and the defects of the material under test. In recent years, DINFO developed piezopolymer Interdigital Transducers (IDTs) proven to be suitable to build SHM systems for aerospace applications. Their base material is a Cr/Au-coated PVDF-TrFE copolymer sheet, having a thickness of 100μm and a metallization of 0.1μm on both sides. IDTs are attractive for SHM systems for their capability to select specific Lamb wave modes when designed with appropriate electrode pattern. For a reliable application, it is crucial to characterize the in-plane and out-of-plane displacement of the transducer and to correlate the ultrasonic propagating signal with the Lamb waves dispersion curves in laminates. For example, for a 2 mm aluminum plate A0 mode has dominant out-of-plane displacement, whereas S0 mode has dominant in-plane displacement at the plate's surface. In collaboration with BAM the characterization of free vibrational modes using a 3D laser doppler vibrometer was performed. The analysis in the frequency domain was performed using the following parameters: a chirp excitation with frequencies 50-500 kHz and 0.5-1 MHz with 195 Hz and 390 Hz frequency resolution respectively at 100 Vpp for a total of 90 averaged measurements per point. Also propagating modes were characterized by bonding the IDT on a 2 mm aluminum plate and analyzing the in-plane and the out-of-plane components. A0-mode was successfully excited having the main lobe aligned with the main axis of the IDT, confirming the dominant presence of this propagating mode. The results could be used as a basis for design and optimization of the IDTs in terms of directivity and mode selection, and to facilitate interpretation of the ultrasonic guided waves propagating in laminated structures. T2 - 51th Annual Meeting of the Associazione Societa Italiana Di Elettronica CY - Rome, Italy DA - 26.06.2019 KW - Structural Health Monitoring KW - Interdigital Transducer KW - PVDF KW - Ultrasonic guided waves KW - Lamb waves PY - 2019 AN - OPUS4-48382 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni T1 - Characterization of Additive Manufacturing Materials at BAM N2 - The combination of tomographic, microstructural data with other experimental techniques and with modeling is paramount, if we want to extract the maximum amount of information on material and component properties. In particular, quantitative image analysis, statistical approaches, direct discretization of tomographic reconstructions represent concrete possibilities to extend the power of the tomographic 3D representation to insights into the material and component performance. This logic thread equally holds for industrial and academic research and valorizes expensive experiments such as those carried out at synchrotron sources, which cannot be daily repeated. I will show a few examples of possible use of X-ray tomographic data for quantitative assessment of damage evolution and microstructural properties, as well as for non-destructive testing. Examples of micro-structured inhomogeneous materials will be given, such as Composites, Ceramics, Concrete, and Additively manufactured parts. I will also show how X-ray refraction computed tomography (CT) can be highly complementary to classic absorption CT, being sensitive to internal interfaces. Additionally, I will show how Neutron Diffraction, which is extremely well suited to the study of internal stresses, both residual and under external load, can well be coupled to the microstructural framework gained by CT, allowing understanding the microstructure-property relationships in materials. Finally, I will show that BAM is very active in standardization and certification, including production of Reference Materials and Methods. T2 - Skoltech Determination of the microscopic residual stress CY - Moscow, Russia DA - 20.11.2019 KW - Additive Manufacturing KW - Computed Tomography KW - Neutron Diffraction KW - X-ray refraction techniques KW - Composites PY - 2019 AN - OPUS4-49929 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sprengel, Maximilian A1 - Kromm, Arne A1 - Cabeza, S. A1 - Mishurova, Tatiana A1 - Nadammal, N. A1 - Thiede, Tobias A1 - Serrano Munoz, Itziar A1 - Ulbricht, Alexander A1 - Evans, Alexander A1 - Bruno, Giovanni T1 - Combining diffraction methods to non-destructively characterize through thickness residual stress gradients in L-PBF IN718 N2 - Laser based Powder Bed Fusion (L-PBF) is an additive manufacturing technique that has been continuously developed in the past years. It offers unparalleled design freedom and the resulting mechanical properties match, in some cases even exceed, those of materials processed by conventional manufacturing techniques. Nonetheless the process is prone to create Residual Stresses (RS) resulting from the sequential melting and solidification of the material. RS can reduce load bearing capacity and generate unwanted distortions thus diminishing the potential of L-PBF. This research activity aimed at characterizing the RS state in Inconel 718 L-PBF specimens using multiple diffraction methods. The microstructure as well as the surface and bulk residual stresses were investigated. The RS analysis was performed using X-ray, synchrotron and neutron diffraction methods to provide information at different depths within the specimen. The measurements were performed at the Bundesanstalt für Materialforschung und –prüfung (BAM), the EDDI beamline at BESSY II synchrotron and E3 line at BER II neutron reactor of the Helmholtz-Zentrum für Materialien und Energie (HZB) Berlin. The results revealed a depth depending RS state. The longitudinal and transverse stress components measured by X-ray and synchrotron at the surface agree well, exhibiting stress values around the yield strength of the material. In addition, synchrotron mapping showed gradients along the width and length of the sample for the longitudinal and transverse stress components. Lower RS values compared to surface RS were measured in the bulk of the material using neutron diffraction. The longitudinal stress component in the bulk was tensile and gradually decreased towards the edge of the specimen. The normal component however did not change significantly along the specimen dimensions and was of compressive nature. The transversal component was almost negligible. The results indicate that a stress re-distribution takes place during the deposition of the consecutive layers, which has to be further investigated. T2 - First European Conference on Structural Integrity of Additively Manufactured Materials CY - Trondheim, Norway DA - 09.09.2019 KW - Additive Manufacturing KW - Residual Stress KW - Diffraction PY - 2019 AN - OPUS4-49804 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schreier, Andy A1 - Liehr, Sascha A1 - Wosniok, Aleksander A1 - Krebber, Katerina T1 - Comparision of solution approaches for distributed humidity sensing in PFGI-POF N2 - We compare four different sensing solutions suitable for distributed fiber optic humidity sensing in per uorinated graded-index polymer optical fibers (PFGI-POFs). Compared to silica fbers, polymer optical fibers over advantageous beneffits including signifficantly higher break down strain, fracture toughness and humidity sensitivity. Various humidity-related effects in PFGI-POFs have been reported in the last years including measured attenuation and length changes as well as Brillouin frequency and Bragg wavelength shifts. The four aforementioned methods could serve as a basis for distributed and quasi-distributed humidity sensing and are described here closely with an emphasis on plausible cross effects to temperature and strain. The main focus of this paper lies on the comparison of four approaches with regard to method complexity, sensitivity to humidity, spatial resolution, real-time capability and effort to compensate for cross effects. T2 - SPIE 2019 International Symposium on Optics + Optoelectronics: Optical Sensors CY - Prague, Czech Republic DA - 01.04.2019 KW - Polymer optical fibre KW - Distributed sensing KW - Humidity PY - 2019 AN - OPUS4-47741 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bulling, Jannis A1 - Gravenkamp, Hauke T1 - Comparison of different models for stress singularities in higher order finite element methods for elastic waves N2 - The Spectral Element Method (SEM) has been proven to be an efficient numerical method for solving the wave equation in linear elastic bodies. This efficiency is reduced if a stress singularity is present in the body. For example, re-entrant corners, material interfaces, fixed boundaries, and especially crack tips can cause stress singularities. To preserve the efficiency of the SEM, special solution strategies are required. There are many approaches which consider stress singularities, but comparisons are rare for dynamic problems. Finding an efficient model is an important step for many applications. In particular, applications for structural health monitoring and non-destructive evaluation rely on accurate and efficient crack models. In this contribution, we present several models to capture singularities in combination with the SEM. The theory behind the models are shortly summarized and we show results for different benchmark problems in two dimensions. The first model deploys a new class of singular elements. For these singular elements, the crack tip approximation is computed based on the static Scaled Boundary Finite Element Method (SBFEM). The second model uses the continued‐fraction‐based SBFEM, while the third model uses an hp-refinement near the singularity. The models are compared among each other and evaluated in terms of their respective efficiency and accuracy. T2 - GAMM 2019 CY - Vienna, Austria DA - 18.02.2019 KW - SBFEM KW - Stress singularities KW - Higher order FEM PY - 2019 AN - OPUS4-47753 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Scheuschner, Nils A1 - Altenburg, Simon A1 - Pignatelli, Giuseppe A1 - Maierhofer, Christiane A1 - Straße, Anne A1 - Gornushkin, Igor B. A1 - Gumenyuk, Andrey T1 - Comparison of in-situ OES and Thermography in the LMD process N2 - In this talk optical emission spectroscopy (OES) and thermographic measurements of the Laser Metal Deposition Process (LMD) are presented. T2 - Workshop on Additive Manufacturing: Process, materials, simulation & implants CY - BAM, Berlin, Germany DA - 13.05.2019 KW - Additive Manufacturing KW - Infrared Thermography PY - 2019 AN - OPUS4-48054 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ratassepp, M. A1 - Rao, J. A1 - Yu, X. A1 - Fan, Z. A1 - Lugovtsova, Yevgeniya A1 - Prager, Jens T1 - Considering anisotropy in guided wave tomography for composite laminates N2 - Recently, various guided wave tomography algorithms have been developed to map structural changes from remote locations. The focus has been on structures made of isotropic materials and little work has been done on structures made of anisotropic materials. Primary complication to implement tomography in composite laminates is associated with the complex forward model to accurately simulate the 3-D guided wave propagation. In this study, we demonstrate that guided wave propagation can be approximated by an equivalent 2-D acoustic model. It is based on finite-difference discretization method in which the wave-field is parameterized by phase velocity and dimensionless anisotropic parameters. The reconstruction of defects is based on a full-waveform inversion algorithm and was implemented on the data obtained from finite element simulations. Results on a localized stiffness defects in composite plates with various layups demonstrate the attractiveness of the proposed methodology. T2 - International Symposium on Nondestructive Characterization of Materials (ISNCM 2019) CY - Portoroz, Slovenia DA - 17.09.2019 KW - Lamb waves KW - Ultrasonic Guided Waves KW - Multilayered structures PY - 2019 AN - OPUS4-50059 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Vössing, Konrad A1 - Gaal, Mate A1 - Niederleithinger, Ernst T1 - Contactless testing of wood-based materials with novel air-coupled ultrasonic transducers N2 - The detection of delamination, rot and cracks causing a decrease of strength in wooden construction elements is a key task for nondestructive testing (NDT). Air-coupled ultrasound (ACU) is used to detect flaws without having to provide contact to the surface or otherwise affect the object. Novel ferroelectric transducers with a high signal-to-noise ratio enable an accurate flaw detection. Transducers made of cellular polypropylene (PP) are suitable for characterizing wood-based materials (WBM) because their extremely low Young’s modulus and low density mean a favorable acoustic impedance for the transmission of ultrasonic waves between the transducer and air. The transducers can be applied during the production of WBM and during its service life. The device enables a fast in-situ recognition of defects with frequencies between 90 kHz and 250 kHz. Measurements can be performed in through transmission for a high resolution or in pulse-echo technique in case of one-sided access at the expense of reduced signal strength. Ultrasonic quality assurance for wood is an important attempt to increase the acceptance of wooden structures and towards sustainability in civil engineering in general. T2 - 21. International Nondestructive Testing and evaluation of Wood Symposium CY - Freiburg, Germany DA - 24.09.2019 KW - Air-coupled ultrasound KW - Defect detection KW - Nondestructive Testing KW - Timber PY - 2019 AN - OPUS4-49170 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waske, Anja T1 - Cooling and energy harvesting using magnetic materials N2 - To date, there are very few technologies available for the conversion of low-temperature waste heat into electricity. Thermomagnetic generators are one approach proposed more than a century ago. Such devices are based on a cyclic change of magnetization with temperature. For thermomagnetic materials, we used a commercial magnetocaloric alloy with a transition temperature of 300 K. T2 - Summer School CY - Szczecin, Poland DA - 26.09.2019 KW - X-Ray Imaging KW - Energy harvesting KW - Magnetocaloric KW - Material Science KW - Non-destructive testing PY - 2019 AN - OPUS4-50155 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Strangfeld, Christoph T1 - Correlation between the electric impedance and the water layer thickness in partially saturated screed samples N2 - Discussion of material moisture in liquid and vapour phase. Prediction of the pore saturation in partially saturated pores in building materials. Correlation between the electric impedance and the water layer thickness in partially saturated screed samples. T2 - 10. CMM Tagung CY - Ettlingen, Germany DA - 10.10.2019 KW - Embedded sensors KW - Corresponding relative humidity KW - Electrical impedance KW - Material moisture KW - Building materials KW - Partiallly saturated pores PY - 2019 AN - OPUS4-49261 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lugovtsova, Yevgeniya A1 - Mesnil, Olivier A1 - Bulling, Jannis A1 - Prager, Jens A1 - Boller, Christian T1 - Damage Quantification in Aluminium-CFRP Composite Structures using Guided Wave Wavenumber Mapping N2 - The use of composite materials is associated not only with the advantages of weight reduction and improved structural performance but also with the risk of barely visible impacts or manufacturing damages. One of the promising techniques for the detection and characterisation of such damages is based on ultrasonic guided wave propagation and analysis. However, the multimodal nature and dispersive behaviour of these waves make their analysis difficult. Various signal processing techniques have been proposed for easier interpretation of guided wave signals and extraction of the necessary information about the damage. One of them is the wavenumber mapping which consists of creating a cartography of the wavenumber of a propagating mode over an inspected area, using a dense wavefield acquisition measured for example with a scanning laser Doppler vibrometer. This technique allows both the quantification of the in-plane size and the depth of damage, for example, impact-induced delamination in composite laminates. In this contribution, wavenumber mapping is applied to a delaminated aluminium-CFRP composite structure which corresponds to composite-overwrapped pressure vessels used for storing gases in aerospace and automotive industries. The analysis of experimental data obtained from measurements of guided waves propagating in an aluminium-CFRP composite plate with impact-induced damage is performed. The output of the imaging is a three-dimensional representation of the delamination induced by the impact. Good agreement between conventional ultrasonic testing and guided wave damage mapping can be found. T2 - 11th International Symposium on NDT in Aerospace CY - Paris Saclay, France DA - 13.11.2019 KW - Damage assessment KW - Lamb waves KW - Multilayered structures KW - Wavefield analysis KW - Impact damage PY - 2019 AN - OPUS4-49662 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Casperson, Ralf T1 - DICONDE für ET N2 - Evaluierung der Eignung von DICONDE zur Speicherung von Wirbelstromprüfdaten im Kontext der Industrie/ZfP 4.0. T2 - 3. Sitzung des DGZfP FA ZfP 4.0 UA Schnittstellen CY - Bochum, Germany DA - 28.08.2019 KW - Wirbelstromprüfung KW - DICONDE KW - ZfP 4.0 KW - Industrie 4.0 PY - 2019 AN - OPUS4-48839 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni A1 - Thiede, Tobias A1 - Mishurova, Tatiana A1 - Ulbricht, Alexander A1 - Sprengel, Maximilian A1 - Kromm, Arne A1 - Serrano Munoz, Itziar A1 - Evans, Alexander T1 - Diffraction-based experimental determination of Residual Stress in AM parts: A critical discussion N2 - Additive manufacturing (AM) technologies have experienced an exceedingly rapid growth, not always paralleled by the knowledge about the materials properties and performance. In particular, residual stress (RS) has been soon recognized as an issue in AM parts, so that parts are always post-heat-treated. Moreover, much effort has been spent on simulating RS, especially using finite element methods. The experimental determination of RS has thereby become increasingly important, and even simple data constitute (to date) a piece of knowledge to fill the above-mentioned gap. In particular, diffraction methods, which are basically non-destructive, offer enormous possibilities to gain knowledge on real components, since neutrons and synchrotron radiation can penetrate even heavy metals up to several millimeters (or even centimeters). Indeed, some success has been obtained, and the knowledge about the origins of the RS fields, as well as their variation as a consequence of heat or mechanical treatments, has been greatly expanded. In this talk, a few success stories will be outlined. It will be shown how the determination of RS in metallic parts (with focus on those produced by laser powder bed fusion) has even allowed showing that process parameters that were considered unimportant play a major role in the onset of stress. However, while RS is starting to be considered in the part design, deposition strategy (e.g. build plate temperature), and even in the definition of the relevant metric to assess the quality of a part, much is still to be investigated about the hypotheses underlying its experimental determination. Therefore, some aspects to be aware of, or even to date unclear will also be discussed, such as the determination of the reference unstrained samples and of the principal axes of stress. All these aspects will draw the path towards a comprehensive understanding of the process-structure-performance relationships in AM materials and parts. T2 - MSTAM 2019 CY - Bremen, Germany DA - 10.12.2019 KW - Elastic Constants KW - Residual Stress KW - Additive Manufacturing KW - Neutron Diffraction PY - 2019 AN - OPUS4-50020 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Léonard, Fabien T1 - Digital image analysis procedures for dimension, dimensional error, and 3D bulk defect assessment N2 - XCT is a powerful technique for dimensional measurements of AM parts. AM parts pose new challenges to the metrologists and CT specialists. Robust digital image analysis have been proposed for dimensional measurements and defect detections based on experience within the MetAMMI project. T2 - Workshop on additive manufacturing CY - Berlin, Germany DA - 13.05.2019 KW - X-ray computed tomography KW - Metrology KW - Implant PY - 2019 AN - OPUS4-48264 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zscherpel, Uwe A1 - Ewert, Uwe T1 - Digitale industrielle Rdiographie im Anlagenbau N2 - Der Ersatz von Röntgenfilmen durch digitale Detektoren in der Zerstörungsfreien Prüfung im Anlagenbau wird seit 2013 durch neue ISO-Normen unterstützt. Nach der Erfolgsgeschichte der digitalen Photographie und der fast voll-ständigen Ablösung der Filmtechnik in der optischen Bilderfassung wird erwartet, dass sich der Übergang von der Filmradiographie zur digitalen Radiographie schnell vollzieht. Dieser Trend ist derzeit so noch nicht zu beobachten. Zur mobilen Prüfung wird in Europa immer noch vorrangig die Filmradiographie und nur teilweise die Computerra-diographie mit Speicherfolien eingesetzt. Im Bereich der stationären Prüftechnik haben sich die Matrixdetektoren (DDA) weitgehend durchgesetzt, wobei es auch hier noch alternative Detektoren wie Bildverstärker und Fluorosko-pe gibt. Mit Einführung der DIN EN ISO 17636-2 zur Schweißnahtprüfung wird seit 2013 erstmalig geregelt, wie man einen digitalen Detektor für die technische Radiographie auswählen soll, um im Vergleich zur Filmradiographie eine äquivalente Bildqualität zu erhalten. Essentielle Parameter bestimmen, ob die geforderte Bildgüte (Fehlernachweiß-empfindlichkeit) erreicht wird. Ein Überblick zeigt, welche Parameter für den praktischen Einsatz wichtig sind und wie sie ermittelt werden. Praktische Einsatzbeispiele im Anlagenbau werden diskutiert. T2 - 47. Sondertagung - Schweißen im Anlagenbau CY - Munich, Germany DA - 17.02.2019 KW - Industrielle Radiographie KW - Filmersatz KW - Normung KW - Bildqualitätsnachweis PY - 2019 UR - www.sondertagung.de AN - OPUS4-50525 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Léonard, Fabien T1 - Distance transforms and correlation maps: advanced impact damage characterisation in composite panels N2 - One of the great strengths of X-ray computed tomography over conventional inspection methods (ultrasound, thermography, radiography) is that it can image damage in 3D. However for curved or deformed composite panels, it can be difficult to automatically ascribe the damage to specific plies or inter-ply interfaces. An X-ray computed tomography (CT) data processing methodology is developed to extract the through-thickness distribution of damage in curved or deformed composite panels. The method is applied to [(0°/90°)2]s carbon fibre reinforced polymer (CFRP) panels subjected low velocity impact damage (5 J up to 20 J) providing 3D ply-by-ply damage visualisation and analysis. Our distance transform approach allows slices to be taken that approximately follow the composite curvature allowing the impact damage to be separated, visualised and quantified in 3D on a ply-by-ply basis. In this way the interply delaminations have been mapped, showing characteristic peanut shaped delaminations with the major axis oriented with the fibres in the ply below the interface. This registry to the profile of the panel constitutes a significant improvement in our ability to characterise impact damage in composite laminates and extract relevant measurements from X-ray CT datasets. T2 - Dagstuhl Seminar 19151 Quantitative data visualisation challenge CY - Dagstuhl, Germany DA - 11.04.2019 KW - Computed tomography KW - X-ray computed tomography KW - Data processing PY - 2019 AN - OPUS4-47830 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wosniok, Aleksander A1 - Schreier, Andy A1 - Krebber, Katerina T1 - Distributed BOFDA measurement on an 86 m long perfluorinated polymer optical fiber N2 - We present our research on the development of a Brillouin optical frequency-domain analysis (BOFDA) using a perfluorinated graded-index polymer optical fiber (PFGI-POF) as a sensing fiber. The described works include investigations both on the selection of the setup components with respect to mode coupling effects and on the impact of the humidity cross-sensitivity. The suitability of the developed POF-based BOFDA is proved by a distributed measurement on an 86 m long PFGI-POF recorded with the spatial resolution of 6 m. T2 - 28th International Conference on Plastic Optical Fibers CY - Yokohama, Japan DA - 20.11.2019 KW - Brillouin sensing KW - BOFDA KW - Perfluorinated graded-index polymer optical fiber KW - PFGI-POF PY - 2019 AN - OPUS4-49866 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schreier, Andy T1 - Distributed Brillouin sensing in polymer optical fibers N2 - A brief overview about the results obtained within the BAM PhD framwork. T2 - Meeting of the Terahertz-Photonics-Group at IHF, Technische Universität Braunschweig CY - Braunschweig, Germany DA - 17.07.2019 KW - Brillouin KW - Distributed sensing KW - Polymer optical fibre PY - 2019 AN - OPUS4-48501 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wosniok, Aleksander A1 - Krebber, Katerina T1 - Distributed fiber optic sensing for structural health monitoring of pipelines and structures in oil and gas industry N2 - Introduction of the state-of-the-art measurement technologies for distributed fiber optic sensing used for structural health monitoring of pipelines and structures in oil and gas industry. T2 - Workshop mit Federal University of Rio de Janeiro und Vallourec Group Brasil CY - Berlin, Germany DA - 20.05.2019 KW - Pipeline monitoring KW - Distributed Brillouin sensing KW - Fiber optic sensor PY - 2019 AN - OPUS4-48048 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Liehr, Sascha A1 - Breithaupt, Mathias A1 - Krebber, Katerina T1 - Distributed Humidity Sensing in PMMA Polymer Optical Fibers N2 - The distributed measurement of relative humidity is a sought-after capability for a wide range of applications in civil engineering and structural health monitoring. We show that polymethyl methacrylate (PMMA) optical fi-bers can be employed as a sensor medium to conduct distributed humidity measurement by analyzing Rayleigh backscattering traces obtained by OTDR. We make use of the effect that water penetrates the fiber core and directly influences the local fiber attenuation and Rayleigh backscatter coefficient. We conducted distributed backscattering analysis for two different pulse wavelengths: 500 nm and 650 nm. The 650 nm results are susceptible to both, attenuation changes and backscatter changes, whereas backscatter results at 500 nm are not affected by humidity-induced attenuation and only exhibit a change of Rayleigh backscattered power as a function of humidity. The combined measurement and analysis of both parameters at these two wavelengths has the advantage that cross-sensitivities on backscatter change and attenuation, such as strain and tempera-ture changes, could be separated from the humidity response of the fiber. We present laboratory results for a humidity range between 30% and 90% for both pulse wavelengths: including step responses, humidity cycles and hysteresis analysis. In addition to the attenuation and backscatter coefficient dependence, we also analyze optical runtime changes as a function of humidity. POFs have the advantage that they can be directly embed-ded into materials such as concrete or soil to measure water content or localize water ingress. Standard step-index PMMA POFs can be used as a distributed relative humidity sensor up to 200 m distance. T2 - The 28th International Conference on Plastic Optical Fibers CY - Yokohama, Japan DA - 20.11.2019 KW - Distributed humidity sensor KW - PMMA KW - Rayleigh scattering KW - Polymer optical fiber KW - Distributed sensor KW - Optical fiber sensor KW - OTDR PY - 2019 AN - OPUS4-49868 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Bernd R. T1 - Division 8.5 - Micro NDE - Key Competence Areas N2 - Der Vortrag gibt einen Überblick über die Kernkompetenzen des Fachbereichs 8.5 Mikro-ZfP (CT Apparaturen, Röntgen-Refraktion, WAXS - Texturanalyse, Datenkorrektur, Rekonstruktionsalgorithmen, Bildanalyse, dimensionelle Kontrolle, Multi-Source Datenfusion und Kombination, micromechanische Eigenschaften mittels Neutronen Diffraktion), im Hinblick auf die Charakterisierung von Leichtbauwerkstoffen (Faserverbunde, Aluminium und Titan MMCs), die in der Luftfahrt verwendet werden. Der Schwerpunkt liegt dabei auf der Charakterisierung mittels Synchrotron und Röntgen Refraktionstechniken sowie Computertomographie. N2 - The lecture gives an overview of the core competencies of the department 8.5 Micro NDT (CT equipment, X-Ray Refraction, WAXS - Texture analysis, Data correction, Reconstruction algorithms, Image analysis, Dimensional control, Multi-Source Data Fusion and Combination, Micromechanical Properties by Neutron Diffraction) with regard to the characterization of lightweight materials (fibre composites, aluminum and titanium MMCs) used in aviation. The focus is on characterization by synchrotron and X-ray refraction techniques as well as computed tomography. T2 - DGZfP Fachausschuss Luftfahrt CY - BAM - Berlin, Germany DA - 18.04.2019 KW - Synchrotron KW - Refraction KW - Microstructure Characterization PY - 2019 AN - OPUS4-47856 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Madia, Mauro A1 - Werner, Tiago A1 - Sprengel, Maximilian A1 - Evans, Alexander A1 - Serrano Munoz, Itziar A1 - Zerbst, Uwe T1 - Effect of residual stresses on crack propagation in Laser Beam Melted (LBM) additively manufactured 316L N2 - Residual stresses count among the most limiting factors in the application of additively manufactured materials in safety relevant components subject to cyclic loading. The source of such stresses is inherent in the manufacturing Laser Beam Melted (LBM) process due to rapid cooling and solidification and their distribution in the specimen or component is not homogeneous, but it is usually characterized by high gradients. Moreover, the magnitude of the residual stress field depends very much on the orientation, being higher in the build direction. Many works in the literature advise to carry out a post-LBM treatment to relieve residual stresses, even though particular attention should be paid in choosing the parameters for the thermal treatment in order to avoid microstructural/phase transformations, which would affect greatly the mechanical properties of the material. Particularly in the case of the austenitic stainless steel 316L, it has been shown that annealing at high temperatures (above 900°C), besides relieving the residual stresses, may cause recrystallization, grain growth and even phase transformation. In contrast, if a too low annealing temperature is chosen in order to preserve the microstructure, the residual stresses cannot be completely relieved. This work aims to address the effect of residual stresses on short and long crack propagation for SEN(B) specimens made of 316L fabricated by LBM, in which notches have been machined by electro-discharge machining (EDM) on the mid-plane, perpendicular to the build direction. The specimens underwent different annealing treatments in inert atmosphere, in which the maximum temperature has been varied up to 900°C. The amount of residual stresses and their distribution has been measured by X-ray and neutron diffraction and the specimens have been subject to cyclic loading in a resonant testing machine. The tests show a massive influence of the residual stresses in the build direction on the resistance to fatigue crack propagation of additively manufactured 316L. Finally, a comparison with conventionally manufactured 316L is presented. T2 - Fourth Symposium on Structural Integrity of Additive Manufactured Materials and Parts CY - Gaylord National Resort And Convention Center; National Harbor, MD, USA DA - 07.10.2019 KW - Fatigue Crack Propagation KW - Additive Manufacturing KW - Residual Stresses PY - 2019 AN - OPUS4-49415 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Jan P. A1 - Krankenhagen, Rainer T1 - Ein Blick unter die Oberfläche von Windkraftanlagen durch Thermografie N2 - Rotorblätter von Windkraftanlagen sind hohen Belastungen ausgesetzt. Nach Jahren der Nutzung können Klebeverbindungen unter der Oberfläche versagen. Thermografie soll die Zustandsüberwachung während der gesamten Lebensdauer verbessern. N2 - Rotor blades of wind power generators are subject to high strains. After years of use, adhesive bonds under the surface may fail. Thermography is intended to improve condition monitoring during the entire service life. T2 - Hannover Messe 2019 CY - Hanover, Germany DA - 1.4.2019 KW - Wiederkehrende Prüfung KW - Thermografie KW - Klebeverbindungen KW - Rotorblatt KW - GFK PY - 2019 AN - OPUS4-49160 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -