TY - CONF A1 - Oster, Simon A1 - Maierhofer, Christiane A1 - Mohr, Gunther A1 - Hilgenberg, Kai A1 - Ulbricht, Alexander A1 - Altenburg, Simon T1 - Investigation of the thermal history of L-PBF metal parts by feature extraction from in-situ SWIR thermography N2 - Laser powder bed fusion is used to create near net shape metal parts with a high degree of freedom in geometry design. When it comes to the production of safety critical components, a strict quality assurance is mandatory. An alternative to cost-intensive non-destructive testing of the produced parts is the utilization of in-situ process monitoring techniques. The formation of defects is linked to deviations of the local thermal history of the part from standard conditions. Therefore, one of the most promising monitoring techniques in additive manufacturing is thermography. In this study, features extracted from thermographic data are utilized to investigate the thermal history of cylindrical metal parts. The influence of process parameters, part geometry and scan strategy on the local heat distribution and on the resulting part porosity are presented. The suitability of the extracted features for in-situ process monitoring is discussed. T2 - Thermosense: Thermal Infrared Applications XLIII CY - Online meeting DA - 12.04.2021 KW - SWIR camera KW - Additive manufacturing (AM) KW - Selective laser melting (SLM) KW - Laser beam melting (LBM) KW - In-situ monitoring KW - Infrared thermography PY - 2021 UR - https://www.spiedigitallibrary.org/conference-proceedings-of-spie/11743/117430C/Investigation-of-the-thermal-history-of-L-PBF-metal-parts/10.1117/12.2587913.short?SSO=1&tab=ArticleLink AN - OPUS4-52540 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Altenburg, Simon A1 - Scheuschner, Nils T1 - Prozessüberwachung in der additiven Fertigung von Metallen - das Projekt ProMoAM N2 - Prozessüberwachung in der additiven Fertigung von Metallen - das Projekt ProMoAM. In diesem Vortrag wird das gesamte Projekt vorgestellt. Dabei wird auf die Thermografie im LMD und L-PBF Prozess näher eingegangen. Hierbei werden sowohl stationäre als auch mit bewegte Systeme vorgestellt. T2 - Webinar: Inline-Messtechnik und –Prozessüberwachung CY - Online meeting DA - 01.07.2020 KW - Pulverbettverfahren KW - Laser Metal Deposition KW - Thermografie KW - Optische Tomografie PY - 2020 UR - https://quality-engineering.industrie.de/webinarreihe-additive-verfahren/#Inline-Messtechnik AN - OPUS4-50962 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mohr, Gunther A1 - Altenburg, Simon A1 - Ulbricht, Alexander T1 - In situ thermography and optical tomography in LBM - comparison to CT N2 - - Successful proof of concept of synchronous in-situ monitoring of a L-PBF process by thermography and optical tomography - Examination method for data analysis - Identification of correlations between measured signals and defects - Identification of sources of misinterpreting T2 - Workshop on Additive Manufacturing: Process , materials , simulation & implants CY - Berlin, Germany DA - 13.05.2019 KW - Laser Powder Bed Fusion KW - Thermography KW - Optical Tomography KW - Computed Tomography KW - Additive Manufacturing KW - 3D printing PY - 2019 AN - OPUS4-48521 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mohr, Gunther A1 - Altenburg, Simon A1 - Hilgenberg, Kai ED - Wei, Z. ED - Pang, J. T1 - On critical shifts of the process window due to heat accumulation in laser powder bed fusion N2 - Safety-critical applications of products manufactured by laser powder bed fusion (PBF-LB/M) are still limited to date. This is mainly due to a lack of knowledge regarding the complex relationship between process, structure, and resulting properties. The assurance of homogeneity of the microstructure and homogeneity of the occurrence and distribution of defects within complexly shaped geometries is still challenging. Unexpected and unpredicted local inhomogeneities may cause catastrophic failures. The identification of material specific and machine specific process parameter windows for production of fully dense simple laboratory specimens is state of the art. However, the incorporation of changing thermal conditions that a complexly shaped component can be faced with during the manufacturing process is often neglected at the stage of a process window determination. This study demonstrates the tremendous effect of changing part temperatures on the defect occurrence for the broadly used stainless steel alloy AISI 316L. Process intrinsic variations of the surface temperature are caused by heat accumulation which was measured by use of a temperature adjusted mid-wavelength infrared (MWIR) camera. Heat accumulation was triggered by simple yet effective temporal and geometrical restrictions of heat dissipation. This was realized by a variation of inter layer times and reduced cross section areas of the specimens. Differences in surface temperature of up to 800 K were measured. A severe development of keyhole porosity resulted from these distinct intrinsic preheating temperatures, revealing a shift of the process window towards unstable melting conditions. The presented results may serve as a warning to not solely rely on process parameter optimization without considering the actual process conditions a real component is faced with during the manufacturing process. Additionally, it motivates the development of representative test specimens. T2 - The 76th IIW Annual Assembly and International Conference On Welding And Joining (IIW 2023) CY - Singapore, Singapore DA - 16.07.2023 KW - Additive manufacturing KW - Laser powder bed fusion KW - Laboratory specimens KW - Process parameter optimization KW - Heat accumulation KW - Keyhole porosity KW - Infrared thermography PY - 2023 SP - 1 EP - 8 AN - OPUS4-58024 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Oster, Simon A1 - Scheuschner, Nils A1 - Chand, Keerthana A1 - Breese, Philipp Peter A1 - Becker, Tina A1 - Heinrichsdorff, F. A1 - Altenburg, Simon T1 - From Thermographic In-situ Monitoring to Porosity Detection – A Deep Learning Framework for Quality Control in Laser Powder Bed Fusion N2 - In this study, we present an enhanced deep learning framework for the prediction of porosity based on thermographic in-situ monitoring data of laser powder bed fusion processes. The manufacturing of two cuboid specimens from Haynes 282 (Ni-based alloy) powder was monitored by a short-wave infrared camera. We use thermogram feature data and x-ray computed tomography data to train a convolutional neural network classifier. The classifier is used to perform a multi-class prediction of the spatially resolved porosity level in small sub-volumes of the specimen bulk. T2 - SMSI - Sensor and Measurement Science International 2023 CY - Nürnberg, Germany DA - 08.05.2023 KW - Porosity KW - Laser powder bed fusion KW - In-situ monitoring KW - Thermography KW - Machine Learning PY - 2023 UR - https://www.ama-science.org/proceedings/details/4404 DO - https://doi.org/10.5162/SMSI2023/C5.4 SP - 179 EP - 180 AN - OPUS4-57616 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon A1 - Scheuschner, Nils A1 - Maierhofer, Christiane A1 - Ulbricht, Alexander A1 - Mohr, Gunther A1 - Heinrich, P. A1 - Baum, D. A1 - Hilgenberg, Kai T1 - In-situ Prozessüberwachung in der additiven Fertigung von Metallen mittels optischer Verfahren N2 - Einer der aussichtsreichsten Ansätze, die Qualität und Sicherheit der gefertigten Teile in der metallbasierten additiven Fertigung (AM) zu erhöhen und die Notwendigkeit aufwändiger und zeitintensiver, zerstörender oder zerstörungsfreier Prüfungen (ZfP) nach der Fertigung zu verringern, liegt in dem Einsatz von in-situ Prozessüberwachungstechniken. Bereits jetzt werden erste Messsysteme zur Kontrolle der Energiequelle, des Bauraums, des Schmelzbades und der Bauteilgeometrie kommerziell angeboten. Weitere ZfP Verfahren, wie z.B. die aktive und passive Thermografie, werden in der Literatur als geeignet für die in-situ Anwendung angesehen, allerdings gibt es noch wenig konkrete praktische Umsetzungen, da die Möglichkeiten und individuellen Grenzen dieser Methoden, angewendet auf AM, noch nicht ausreichend erforscht sind. Aus diesem Grund verfolgt die BAM mit dem Projekt „Process Monitoring of AM“ (ProMoAM) im Themenfeld Material das Ziel, Verfahren des Prozessmonitorings zur in-situ Bewertung der Qualität additiv gefertigter Metallbauteile weiterzuentwickeln. Im Beitrag wird zunächst das Projekt vorgestellt und anschließend der Fokus auf eine Messserie gelegt, in der Probekörper aus dem austenitischen Edelstahl 316L mit lokal variierenden Prozessparametern mittels selektiven Laserschmelzen (L-PBF) aufgebaut wurden. Der Bauprozess wurde hierbei durch das maschineneigene, koaxial arbeitende Photodiodensystem (Melt-Pool-Monitoring), einer Mittelwellen-Infrarotkamera und einer optischen Tomografiekamera im sichtbaren Wellenlängenbereich (Langzeitbelichtung für die Dauer eines Lagenaufbaus mit einer CMOS-Kamera mit hoher Ortsauflösung) simultan überwacht. Als Referenz für diese Methoden wurden die Probekörper mittels Computertomografie untersucht. Für die dabei anfallenden teils großen Datenmengen wurden Algorithmen für ein effizientes Preprocessing entwickelt. Es wurden Merkmale der Messdaten in Korrelation zu Fehlern und Inhomogenitäten extrahiert, welche für die einzelnen Methoden vergleichend vorgestellt und diskutiert werden. T2 - 5. Tagung des Arbeitskreises Additiv gefertigte Bauteile und Strukturen CY - Online meeting DA - 04.11.2020 KW - Additive Fertigung KW - Prozessüberwachung KW - Thermografie KW - Optische Tomografie KW - Computertomografie KW - L-PBF KW - AM KW - CT KW - In-situ PY - 2020 AN - OPUS4-51627 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hilgenberg, Kai A1 - Mohr, Gunther A1 - Altenburg, Simon A1 - Ulbricht, Alexander A1 - Seeger, Stefan T1 - Prozessmonitoring für die additive Fertigung: Entwicklungen an der BAM N2 - Das Prozessmonitoring stellt einen wichtigen Baustein für eine Qualitätssicherung additiv gefertigter Bauteile dar, insbesondere bei kleinen Losgrößen. Der Vortrag zeigt einen Überblick aktueller Entwicklungen der BAM im Bereich des Prozessmonitorings für das Laserstrahlschmelzen (laser powder bed fusion) metallischer Werkstoffe. Durch Vergleich mit der Referenzmethode Computertomografie wird am Beispiel der thermografischen Verfahren gezeigt, wie relevante Defekte in Bauteilen detektiert werden können und Einsatzpotenziale sowie Limitierungen aufgezeigt. T2 - Forum Additive Fertigung Rheinland-Pfalz CY - Ludwigshafen, Germany DA - 07.11.2019 KW - Optische Tomografie KW - Additive Fertigung KW - Prozessmonitoring KW - Thermografie PY - 2019 AN - OPUS4-49958 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schröder, Jakob A1 - Evans, Alexander A1 - Polatidis, E. A1 - Čapek, J. A1 - Mohr, Gunther A1 - Serrano Munoz, Itziar A1 - Kromm, Arne A1 - Luzin, V. A1 - Bruno, Giovanni T1 - Fundamentals of diffraction-based residual stress and texture analysis of PBF-LB Inconel 718 N2 - Laser powder bed fusion (PBF-LB/M) of metallic alloys is a layer wise additive manufacturing process which provides significant scope for more efficient designs of components, benefiting performance and weight, leading to efficiency improvements for various sectors of industry. However, to benefit from these design freedoms, knowledge of the high produced induced residual stress and mechanical property anisotropy associated with the unique microstructures is critical. X-ray and neutron diffraction are considered the benchmark for non-destructive characterization of surface and bulk internal residual stress. The latter, characterized by the high penetration power in most engineering alloys, allows for the use of diffraction angle close to 90° enabling a near cubic sampling volume to be specified. However, the complex microstructures of columnar growth with inherent crystallographic texture typically produced during PBF-LB/M of metallics present significant challenges to the assumptions typically required for time efficient determination of residual stress. These challenges include the selection of an appropriate set of diffraction elastic constants and a representative strain-free reference for the material of interest. In this presentation advancements in the field of diffraction-based residual stress analysis of L-PBF Inconel 718 will be presented. The choice of an appropriate set of diffraction-elastic constants depending on the underlying microstructure will be described. T2 - MLZ User Meeting 2022 CY - Munich, Germany DA - 08.12.2022 KW - Diffraction KW - Residual Stress KW - Microstructure KW - Texture KW - Mechanical behavior PY - 2022 AN - OPUS4-56804 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Becker, Tina A1 - Altenburg, Simon A1 - Scheuschner, Nils A1 - Maierhofer, Christiane T1 - Multi measurand in-situ monitoring of the laser powder bed fusion process by means of multispectral optical tomography N2 - Laser Powder Bed Fusion (L-PBF), as one of the most promising production process in the field of metal additive manufacturing, enables traditional constructive solutions to be rethought and the manufacturing of optimized components according to the "form follows function" principle. The most significant obstacle for a broad industrial application of the L-PBF process is the inadequate quality assurance during the manufacturing process so far, leading to high production costs. Although several mainly camera based commercial in-process monitoring systems are already available, a deep understanding of the interpretation of the monitored data and correlation with actual defects is still lacking. One reason for this is the reduction of the complex process signature to just one measurement value. The focus of this contribution is the presentation of the multispectral optical tomography as alternative to single measurand in-situ monitoring systems. The potential of this approach is hereby shown on L-PBF printed samples with induced process instabilities. Beyond that, an in-house developed L-PBF printer for further testing of multi-sensor in-situ monitoring systems is presented. T2 - ICAM2021 CY - Online meeting DA - 01.11.2021 KW - In-situ monitoring KW - L-PBF KW - Optical tomography KW - 3d printing KW - Thermography PY - 2021 AN - OPUS4-54388 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon A1 - Scheuschner, Nils A1 - Gumenyuk, Andrey A1 - Straße, Anne A1 - Maierhofer, Christiane T1 - Unraveling thermal radiation by multispectral thermography: Real temperatures in LMD N2 - Additive manufacturing of metals offers the opportunity to build parts with a high degree of complexity without additional costs, opening a new space for design optimization. However, the processes are highly complex and due to the rapid thermal cycles involved, high internal stresses and peculiar microstructures occur, which influence the parts mechanical properties. To systematically examine the formation of internal stresses and the microstructure, in-process spatially resolved measurements of the part temperature are needed. If the emissivity of the inspected part is known, its thermodynamic temperature can be reconstructed by a suited radiometric model. However, in additive manufacturing of metals, the emissivity of the part surface is strongly inhomogeneous and rapidly changing due to variations of, e.g., the degree of oxidation, the material state and temperature. Thus, here, the applicability of thermography in the determination of thermodynamic temperatures is limited. However, measuring the process thermal radiation at different wavelengths simultaneously enables one to separate temperature and emissivity spatially resolved to obtain further insight into the process. Here, we present results of an initial study using multispectral thermography to obtain real temperatures and emissivities in the powderfree LMD process. T2 - 2nd Workshop on In-situ Monitoring and Microstructure Development in Additive Manufactured Alloys CY - Online meeting DA - 19.04.2021 KW - Additive Manufacturing KW - Process monitoring KW - Multispectral thermography KW - Laser metal deposition KW - TES KW - LMD KW - Temperature emissivity separation PY - 2021 AN - OPUS4-52514 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon A1 - Maierhofer, Christiane A1 - Mohr, Gunther A1 - Hilgenberg, Kai T1 - Process monitoring in LBM using thermography and optical tomography N2 - Additive manufacturing (AM) opens the route to a range of novel applications. However, the complexity of the manufacturing process poses a challenge to produce defect-free parts with a high reliability. Since process dynamics and resulting microstructures of AM parts are strongly influenced by the involved temperature fields and cooling rates, thermography is a valuable tool for process monitoring. Another approach to monitor the energy input into the part during process is the use of optical tomography. Common visual camera systems reach much higher spatial resolution than infrared thermography cameras, whereas infrared thermography provides a much higher temperature dynamic. Therefore, the combined application increases the depth of information. Here, we present first measurement results using a laser beam melting setup that allows simultaneous acquisition of thermography and optical tomography from the same point of view using a beam splitter. A high-resolution CMOS camera operating in the visible spectral range is equipped with a near infrared bandpass filter and images of the build plate are recorded with long-term exposure during the whole layer exposing time. Thus, areas that reach higher maximum temperature or are at elevated temperature for an extended period of time appear brighter in the images. The used thermography camera is sensitive to the mid wavelength infrared range and records thermal videos of each layer exposure at an acquisition rate close to 1 kHz. As a next step, we will use computer tomographic data of the built part as a reference for defect detection. This research was funded by BAM within the focus area Materials. T2 - 3rd International Symposium Additive Manufacturing (ISAM 2019) CY - Dresden, Germany DA - 30.01.2019 KW - Additive manufacturing KW - Laser beam melting KW - Thermography KW - Optical Tomography PY - 2019 AN - OPUS4-47299 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 - Altenburg, Simon A1 - Maierhofer, Christiane A1 - Hilgenberg, Kai A1 - Mohr, Gunther A1 - Gumenyuk, Andrey A1 - Straße, Anne A1 - Pittner, Andreas A1 - Günster, Jens A1 - Gornushkin, Igor B. A1 - Pelkner, Matthias A1 - Ehlers, Henrik A1 - Heckel, Thomas A1 - Zscherpel, Uwe A1 - Seeger, Stefan A1 - Bruno, Giovanni T1 - ProMoAM - Verfahrensentwicklung für das Prozessmonitoring in der additiven Fertigung N2 - Verfahren zum in-situ Monitoring der Prozess- und Bauteilparameter sollen Fehlstellen und Inhomogenitäten bereits während der Fertigung nachweisen und zukünftig auch die Regelung der Prozessparameter ermöglichen. T2 - Challenges in Additive Manufacturing: Innovative Materials and Quality Control, Berlin Partner Workshop CY - Berlin, Germany DA - 12.09.2018 KW - Additive Fertigung KW - Prozessmonitoring KW - ProMoAM PY - 2018 AN - OPUS4-46300 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon A1 - Maierhofer, Christiane A1 - Straße, Anne A1 - Gumenyuk, Andrey A1 - Mohr, Gunther A1 - Hilgenberg, Kai T1 - Thermography in metal AM: Comparison of high-speed NIR thermography and MWIR thermography N2 - Additive manufacturing (AM) opens the route to a range of novel applications.However, the complexity of the manufacturing process poses a challenge for the production of defect-free parts with a high reliability. Since process dynamics and resulting microstructures of AM parts are strongly influenced by the involved temperature fields, thermography is a valuable tool for process surveillance. The high process temperatures in metal AM processes allow one to use cameras usually operating in the visible spectral range to detect the thermally emitted radiation from the process. In our work, we compare the results of first measurements during the manufacturing processes of a commercial laser metal deposition (LMD) setup and a laser beam melting (LBM) setup using a MWIR camera with those from a VIS high-speed camera with band pass filter in the NIR range. T2 - Additive Manufacturing Benchmarks 2018 CY - Gaithersburg, MA, USA DA - 18.06.2018 KW - Thermography KW - Additive manufacturing KW - Laser metal deposition KW - Laser beam melting KW - ProMoAM PY - 2018 AN - OPUS4-45401 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon A1 - Maierhofer, Christiane A1 - Mohr, Gunther A1 - Hilgenberg, Kai A1 - Straße, Anne A1 - Gumenyuk, Andrey T1 - Verfahrensentwicklung für das Prozessmonitoring in der additiven Fertigung von Metallen - Thermografie N2 - Aktuell werden Prozessmonitoringsysteme in der additiven Fertigung (AM) zur Überwachung der Energiequelle, des Bauraums, des Schmelzbades und der Bauteilgeometrie zumindest im metallbasierten AM schon kommerziell angeboten. Weitere Verfahren aus den Bereichen der Optik, Spektroskopie und zerstörungsfreien Prüfung werden in der Literatur als geeignet für die in-situ Anwendung bezeichnet, es finden sich aber nur wenige Berichte über konkrete Umsetzungen in die Praxis. Die Bundesanstalt für Materialforschung und -prüfung hat ein neues Projekt gestartet, dessen Ziel die Entwicklung von Verfahren des Prozessmonitorings zur in-situ Bewertung der Qualität additiv gefertigter Bauteile in AM-Prozessen mit Laser- bzw. Lichtbogenquellen ist. Verschiedene Verfahren der zerstörungsfreien Prüfung, wie Thermografie, optische Tomografie, optische Emissionsspektroskopie, Wirbelstromprüfung und Laminografie werden in verschiedenen AM-Prozessen zum Einsatz gebracht und die Ergebnisse fusioniert. Die evaluierten Ergebnisse werden mit Referenzverfahren wie Computertomografie und Ultraschall-Tauchtechnik verglichen. Ziel ist eine deutliche Reduzierung aufwändiger und zeitintensiver, zerstörender oder zerstörungsfreier Prüfungen nach der Fertigung des Bauteiles und zugleich eine Verringerung von Ausschussproduktion. Hier wird das Projekt als Ganzes vorgestellt und der Fokus auf verschiedene Methoden der Temperaturmessung mit Hilfe der Thermografie gelegt. Anforderungen an die Messtechnik für verschiedene AM-Systeme werden diskutiert und erste experimentelle Ergebnisse werden präsentiert. T2 - 3. Tagung des DVM-Arbeitskreises Additiv gefertigte Bauteile und Strukturen CY - Berlin, Germany DA - 07.11.2018 KW - Additive Fertigung KW - Prozessmonitoring KW - ProMoAM KW - Thermografie PY - 2018 AN - OPUS4-46562 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mohr, Gunther A1 - Chaudry, Mohsin Ali A1 - Scheuschner, Nils A1 - Blasón Gonzalez, Sergio A1 - Madia, Mauro A1 - Hilgenberg, Kai T1 - Development of representative test specimens by thermal history transfer in laser powder bed fusion N2 - The use of components manufactured by laser powder bed fusion (PBF LB/M) and subjected to fatigue loading is still hampered by the uncertainty about the homogeneity of the process results. Numerous influencing factors including the component’s geometry contribute to the risk of process instability and resulting inhomogeneity of properties. This drastically limits the comparability of different built parts and requires expensive full component testing. The thermal history as the spatiotemporal temperature distribution has been identified as a major cause for flaw formation. Therefore, it can be hypothesized that a similar thermal history between components and test specimens enhances their comparability. Following this assumption, a strategy is developed to transfer the intrinsic preheating temperature as a measure of comparability of thermal histories from a region of interest of a complex component to a simple test specimen. This transfer concept has been successfully proved by the use of FEM-based macroscale thermal simulations, validated by calibrated infrared thermography. An adoption of the specimen manufacturing process by the adjustment of the inter layer times was established to manufacture specimens which are representatives of a specific region of a large-scale component in terms of the thermal history similarity criterion. The concept is schematically illustrated in Figure 1 and was demonstrated using a pressure vessel geometry from the chemical industry. T2 - 4th Symposium on Materials and Additive Manufacturing CY - Berlin, Germany DA - 12.06.2024 KW - Additive manufacturing KW - Thermal history KW - Laboratory specimens KW - In situ monitoring KW - Representative specimens PY - 2024 AN - OPUS4-60260 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Scheuschner, Nils A1 - Altenburg, Simon A1 - Straße, Anne A1 - Gumenyuk, Andrey A1 - Maierhofer, Christiane T1 - In-situ Thermografie in der additiven Fertigung mittels Laser-Pulver-Auftragsschweißen N2 - Im Rahmen des Themenfeld Projektes „Process Monitoring of AM“ (ProMoAM) evaluiert die BAM gegenwärtig die Anwendbarkeit verschiedenster ZfP-Verfahren, darunter die Thermografie, zur Prozessüberwachung in der additiven Fertigung von Metallen in Hinblick auf die Qualitätssicherung. In diesem Beitrag werden SWIR-Thermografiemessungen während des Bauprozesses mittels Laser Pulver Auftragsschweißen (LPA) vorgestellt. Eine Herausforderung im Rahmen dieser Messungen liegt in der Positionierung der Kamera, welche entweder fixiert am Schweißarm, also mitbewegt, oder fixiert in der Baukammer, also stationär, erfolgen kann, wobei beide Varianten mit individuellen Vor- und Nachteilen verbunden sind. Eine stationäre Befestigung der Kamera ermöglicht zwar eine einfachere Zuordnung der Messdaten zu der jeweiligen Position im Bauteil, führt jedoch bei komplexeren Geometrien zwangsläufig zu Problemen durch Abschattungen und zu defokussierten Bereichen. Zur Auswertung von Thermogrammen, welche durch eine mit dem Schweißarm mitbewegte Kamera aufgenommen wurden, sind hingegen für jedes Bild akkurate Positionsdaten der Kamera nötig um die Messdaten einer Position im Bauteil zuzuordnen. Da die Positionsdaten des Schweißarmes im allgemeinen Fall durch die Anlagensoftware nicht zur Verfügung gestellt werden, muss diese Information durch zusätzliche Messungen aufgezeichnet werden. Hierzu verwenden wir einen an der Kamera befestigten Beschleunigungssensor. Dieser ermöglicht einen zeitlichen Abgleich mit dem vorprogrammierten Verfahrweg des Schweißarmes, welcher im Allgemeinen noch Unsicherheiten bezüglich genauer Geschwindigkeiten und Beschleunigungen offenlässt. Weiterhin untersuchen wir den Einfluss des empfindlichen Spektralbereiches der IR-Kamera durch den Vergleich von Messungen mit verschiedenen schmalbandigen Bandpassfiltern (25 nm FWHM) in einem Bereich von 1150 nm bis 1550 nm. T2 - Thermographie-Kolloquium 2019 CY - Halle (Saale), Germany DA - 19.09.2019 KW - Additive manufacturing KW - 3D printing KW - Thermography KW - Direct energy deposition KW - Laser Metal Deposition KW - 3D Druck KW - Laser Pulver Auftragsschweißen KW - Additive Fertigung KW - Thermografie PY - 2019 AN - OPUS4-49078 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Scheuschner, Nils A1 - Heinrichsdorff, F. A1 - Gordei, A. A1 - Ehlers, Henrik A1 - Kochan, J. A1 - Jahangir, H. A1 - Pelkner, Matthias A1 - Maierhofer, Christiane A1 - Hilgenberg, Kai T1 - In-situ Prozessüberwachung in der additiven Fertigung von Metallen (PBF-LB /M) mittels TT und ET N2 - Durch die additive Fertigung ergeben sich durch die nun mögliche wirtschaftliche Fertigung hochgradig individueller und komplexer metallischer Bauteile in kleinen Stückzahlen bis hinunter zum Einzelstück für viele Industriebereiche ganz neue Möglichkeiten. Gleichzeitig entstehen jedoch neue Herausforderungen im Bereich der Qualitätssicherung, da sich auf statistischen Methoden beruhende Ansätze nicht anwenden lassen, ohne wiederum die Vorteile der Fertigung massiv einzuschränken. Eine mögliche Lösung für dieses Problem liegt in der Anwendung verschiedener In-situ-Überwachungstechniken während des Bauprozesses. Jedoch sind nur wenige dieser Techniken kommerziell verfügbar und noch nicht so weit erforscht, dass die Einhaltung strenger Qualitäts- und Sicherheitsstandards gewährleistet werden kann. In diesem Beitrag stellen wir die Ergebnisse einer Studie über mittels L-PBF gefertigte Probekörper aus der Nickelbasis-Superlegierung Haynes 282 vor, bei denen die Bildung von Defekten durch lokale Variationen der Prozessparameter wie der Laserleistung provoziert wurde. Die Proben wurden in-situ mittels Thermographie, optischer Tomographie, Schmelzbadüberwachung und Wirbelstromprüfung sowie ex-situ mittels Computertomographie (CT) überwacht, mit dem Ziel, die Machbarkeit und die Aussichten der einzelnen Methoden für die zuverlässige Erkennung der Bildung relevanter Defekte zu bewerten. T2 - DGZfP Jahrestagung 2022 CY - Kassel, Germany DA - 23.05.2022 KW - Additive Manufacturing KW - Thermografie KW - Additive Fertigung KW - Thermography PY - 2022 AN - OPUS4-55851 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hassenstein, Christian A1 - Wassermann, Jonas A1 - Hirsch, Philipp Daniel A1 - Heckel, Thomas T1 - Automated self-adjustment of array probe with a robotic ultrasonic test system N2 - Ultrasonic testing (UT) of objects with complex geometries often requires the use of a robotic arm to position the probe perpendicular to the local surface. Using immersion makes it possible to test these objects with standard ultrasonic linear array probes. Here, the probe positions and orientations provided by the robot are used for merging the locally acquired image data into a 3D-reconstruction. The quality of this reconstruction is highly dependent on the alignment of the tool center point (TCP) of the physical probe with the TCP used in the digital model. For common industrial tools, the TCP is usually acquired using geometric features of the tools. However, for ultrasonic arrays in immersion, there is a water standoff between the probe and the test object, therefore the TCP is in free space in front of the array and cannot be acquired with the common method. To overcome this challenge, we propose a method that allows the robotic ultrasonic system to automatically self-adjust the positioning of the UT probe using a test block made of steel with defined geometric features as a target for referencing. For each of the six degrees of freedom, a scan and adjustment routine are established using the data acquired by the UT probe to update the TCP’s position and orientation in the robot control. Given a coarse pre-definition of the TCP and the known target test block, no human interaction is required while the system determines the optimum tool position and orientation. Part of this work will be used to improve and extend standards for robotic ultrasonic test systems, e.g. ISO 24647. T2 - 20th World Conference On Non-Destructive Testing CY - Inchean, South Korea DA - 27.05.2024 KW - Ultrasonic KW - Testing KW - Automation KW - Robotics KW - NDT 4.0 PY - 2024 AN - OPUS4-60565 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hassenstein, Christian A1 - Heckel, Thomas A1 - Hirsch, Philipp Daniel A1 - Vöhringer, Daniel A1 - Prager, Jens T1 - Automatisierte Wanddickenbestimmung an Prüfteilen mit komplexen Geometrien aus anisotropen Werkstoffen N2 - Im Rahmen des Projektes MRO2.0, das sich mit der digitalen Transformation des Servicezyklus von modernen Gasturbinenschaufeln beschäftigt, wurde gezeigt, wie sich automatisiert und flächendeckend die (Rest-)Wanddicke an variabel gekrümmten Prüfgeometrien bestimmen lässt. Es wurde ein Roboterarm verwendet, der ein lineares Ultraschallarray in Tauchtechnik führt und Prüfdaten aufnimmt, die mit einer adaptierten TFM (Total Focusing Method) zu Rekonstruktionen der Außen- und Innenoberfläche verarbeitet werden. In der aktuellen zweiten Projektphase wird die Methode für Werkstoffe erweitert, die anisotrope akustische Eigenschaften aufweisen. In diesem Beitrag wird eine Methode vorgestellt, wie sich die Kristallausrichtung bzw. die richtungsabhängige Schallgeschwindigkeit mittels eines linearen Ultraschallarrays bestimmen lässt. Für den Sendefall eines Randelements in Kontakttechnik können dabei Wellen identifiziert werden, die sich parallel zur Prüfkopfapertur im Prüfobjekt ausbreiten und mit der richtungsabhängigen Schallgeschwindigkeit skalieren. Die ermittelte Schallgeschwindigkeitsverteilung kann dann verwendet werden, um die lokale Wanddickenbestimmung für die Anisotropie zu adaptieren. T2 - 6. Workshop Messtechnische Anwendungen von Ultraschall CY - Drübeck, Germany DA - 17.06.2024 KW - Ultraschallprüfung KW - Anisotropie KW - Turbinenschaufel KW - NDT 4.0 PY - 2024 AN - OPUS4-60568 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krankenhagen, Rainer A1 - Chaudhuri, Somsubrho A1 - Pittner, Andreas A1 - Winterkorn, Rene A1 - Palumbo, Davide A1 - de Finis, Rosa A1 - Galietti, Umberto T1 - Thermographic Investigation of the Anisotropic Behaviour of Additively Manufactured AISI 316 Steel using DED-arc N2 - Additive manufacturing is one of the most promising techniques for industrial production and maintenance, but the specifics of the layered structure must be considered. The Direct Energy Deposition-Arc process enables relatively high deposition rates, which is favourable for larger components. For this study, specimens with different orientations were prepared from one AISI316 steel block – parallel and orthogonal to the deposition plane. Quasistatic tensile loading tests were carried out, monitored by an infrared camera. The obtained surface temperature maps revealed structural differences between both orientations. The consideration of surface temperature transients yields more details about the behaviour of the material under tensile loading than the conventional stress-strain-curve. These preliminary investigations were supplemented by thermographic fatigue trials. Although the anisotropy was also observed during fatigue loading the fatigue behaviour in general was the same, at least for both inspected specimens. The presented results demonstrate the abilities and the potential of thermographic techniques for tensile tests. T2 - 17th Quantitative Infrared Thermography Conference CY - Zagreb, Croatia DA - 01.07.2024 KW - Thermoelastic effect KW - Thermoplastic effect KW - Thermal stress analysis PY - 2024 AN - OPUS4-60574 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hassenstein, Christian A1 - Kieffer, Dennis A1 - Hirsch, Philipp Daniel T1 - Automatisierte Bahnplanung für robotergestützte Ultraschallprüfung mit Arrayprüfköpfen N2 - In der automatisierten Ultraschallprüfung von Komponenten mit komplexen Oberflächengeometrien werden zur Führung des Prüfkopfes zunehmend 6-Achsen-Roboter erprobt. Diese stellen die notwendige Automatisierbarkeit und Flexibilität bereit, um die lokal senkrechte Einschallung sicherzustellen. Durch den Einsatz von linearen Arrays und bildgebenden Verfahren können die Bilder oder die daraus extrahierten Merkmale zu einer Rekonstruktion in 3D zusammengesetzt werden. Die Anforderungen an die Prüfbahnen für die bildgebende Array-Ultraschallprüfung gehen dabei über konventionellen Bahnplanungsprogramme hinaus. Es wird ein Prozess vorgestellt, der Roboterbahnen auf der Grundlage des 3D-Modells von Körpern mit doppelt gekrümmter Oberfläche unter Berücksichtigung der Prüfparameter erzeugt. Hierbei wird zum einen die senkrechte Prüfkopfstellung und zum anderen eine optimale Abdeckung der Oberfläche realisiert. Dabei wird die lokale Oberflächengeometrie beachtet, da diese das Reflexionsverhalten beeinflusst und sich daher auf die optimale Verteilung und Orientierung der Prüfpositionen auswirkt. Damit einhergehend erfolgt eine Ablösung von konventionellen Konzepten, die auf linearen Prüfbahnen basieren, welches spannende neue Prüfstrategien eröffnet. T2 - DGZfP-Jahrestagung 2024 CY - Osnabrück, Germany DA - 06.05.2024 KW - Ultraschallprüfung KW - Phased array KW - Automatisierung KW - NDT 4.0 PY - 2024 AN - OPUS4-60590 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Serrano Munoz, Itziar A1 - Mouiya, Mossaab A1 - Prasek, Marko A1 - Kupsch, Andreas A1 - Bruno, Giovanni T1 - High temperature in-situ heat treatment of a refractory material by means of synchrotron refraction radiography N2 - The stress–strain behavior of certain ceramics, such as aluminum titanate (AT, Al2TiO5), has features that are unusual for brittle material. In particular, a substantial nonlinearity under uniaxial tension, and load–unload hysteresis caused by the increase of the incremental stiffness at the beginning of unloading. These features are observed experimentally and attributed to microcracking. In this study, we investigate the mechanical response of an AT material at room and high temperature. Microstructure and microcracking are analyzed by means of electron microscopy, and both synchrotron micro computed tomography (µCT) and refraction radiography (SXRR). Synchrotron refraction radiography is combined with in-situ heating at high-temperatures (up to 1400°C) to be able to monitor the relative closure of microcracks as a function of increasing/decreasing temperatures. T2 - 21st European Conference on Composite Materials (ECCM21) CY - Nantes, France DA - 02.07.2024 KW - Refractory materials KW - Microcracking KW - Synchrotron µCT and refraction radiography KW - In-situ heating up to 1400°C PY - 2024 AN - OPUS4-60576 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Serrano Munoz, Itziar A1 - Mouiya, Mossaab A1 - Prasek, Marco A1 - Kupsch, Andreas A1 - Bruno, Giovanni T1 - High temperature in-situ heat treatment of a refractory material by means of synchrotron refraction radiography N2 - The stress–strain behavior of certain ceramics, such as aluminum titanate (AT, Al2TiO5), has features that are unusual for brittle material. In particular, a substantial nonlinearity under uniaxial tension, and load–unload hysteresis caused by the increase of the incremental stiffness at the beginning of unloading. These features are observed experimentally and attributed to microcracking. In this study, we investigate the mechanical response of an AT material at room and high temperature. Microstructure and microcracking are analyzed by means of electron microscopy, and both synchrotron micro computed tomography (µCT) and refraction radiography (SXRR). Synchrotron refraction radiography is combined with in-situ heating at high-temperatures (up to 1400°C) to be able to monitor the relative closure of microcracks as a function of increasing/decreasing temperatures. T2 - ECCM21 CY - Nantes, France DA - 02.07.2024 KW - Refractory materials KW - Microcracking KW - Synchrotron µCT and refraction radiography KW - In-situ heating up to 1400°C PY - 2024 UR - https://gem.ec-nantes.fr/en/eccm21-proceedings/ SN - 978-2-912985-01-9 DO - https://doi.org/10.60691/yj56-np80 SP - 47 EP - 53 PB - The European Society for Composite Materials (ESCM) and the Ecole Centrale de Nantes. CY - Nantes AN - OPUS4-60581 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lengas, Nikolaos A1 - Müller, Karsten A1 - Schlick-Hasper, Eva A1 - Neitsch, Marcel A1 - Johann, Sergej A1 - Zehn, Manfred W. T1 - Drop test simulation of packaging for dangerous goods: Investigation of appropriate drop height adjustment N2 - In the approval process of dangerous goods packagings, drop tests onto a flat, essentially unyielding surface are used to assess resistance against mechanical damage. International adopted regulations like ADR and RID define filling good dependent drop heights and filling degrees whilst the user needs to define the maximum gross mass to be tested and approved. Maximum packaging gross mass is defined conservatively and not reached in practice. To meet the defined gross mass in testing, using additives is permitted. However, in some cases, additives are not desirable due to packaging design or filling substance properties. This leads to deviations from the initial gross mass definition. Hence, a certain drop height adjustment is necessary to achieve the required impact loading. Laboratories frequently adjust drop height assuming a perfectly elastic collision which is inaccurate. Appropriate adjustment is not trivial due to energy conversion processes, e.g., plastic deformation. In this work, a test stand is developed for measuring the change in kinetic energy of different packaging designs and filling substances in regulative drop tests. The experimental results are used to validate finite-element (FE) models so that packaging properties can be varied in simulated drop test scenarios. The findings intend to describe the appropriate drop height adjustment of the respective packaging with same design but deviating gross mass to produce comparable mechanical response. The results are highly beneficial for testing laboratories, approval issuing authorities and packaging institutes confronted with the problem of testing packages with gross masses other than those to be approved. T2 - 24th IAPRI World Conference CY - Valencia, Spain DA - 17.06.2024 KW - Dangerous goods packagings KW - FEM KW - Drop test KW - Mechanical response PY - 2024 AN - OPUS4-60607 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon A1 - Scheuschner, Nils A1 - Pignatelli, Giuseppe A1 - Maierhofer, Christiane A1 - Straße, Anne A1 - Gornushkin, Igor B. A1 - Gumenyuk, Andrey T1 - Thermography and optical emission spectroscopy: Simultaneous temperature measurement during the LMD process N2 - For metal-based additive manufacturing, sensors and measuring systems for monitoring of the energy source, the build volume, the melt pool and the component geometry are already commercially available. Further methods of optics, spectroscopy and non-destructive testing are described in the literature as suitable for in-situ application, but there are only a few reports on practical implementations. Therefore, a new BAM project aims to develop process monitoring methods for the in-situ evaluation of the quality of additively manufactured metal components. In addition to passive and active thermography, this includes optical tomography, optical emission and absorption spectroscopy, eddy current testing, laminography, X-ray backscattering and photoacoustic methods. These methods are used in additive manufacturing systems for selective laser melting, laser metal deposition and wire arc additive manufacturing. To handle the sometimes huge amounts of data, algorithms for efficient preprocessing are developed and characteristics of the in-situ data are extracted and correlated to defects and inhomogeneities, which are determined using reference methods such as computer tomography and metallography. This process monitoring and fusion of data of different measurement techniques should result in a significant reduction of costly and time-consuming, destructive or non-destructive tests after the production of the component and at the same time reduce the production of scrap. Here, first results of simultaneous measurements of optical emission spectroscopy and thermography during the laser metal deposition process using 316L as building material are presented. Temperature values are extracted from spectroscopic data by fitting of blackbody emission spectra to the experimental data and compared with results from a thermographic camera. Measurements with and without powder flow reveal significant differences between welding at a pristine metal surface and previously melted positions on the build plate, illustrating the significant influence of the partial oxidation of the surface during the first welding process on subsequent welding. The measurement equipment can either be mounted stationary or following the laser path. While first results were obtained in the stationary mode, future applications for online monitoring of the build of whole parts in the mobile mode are planned. This research was funded by BAM within the focus area Material. T2 - 2nd international congress on welding, additive manufacturing and associated non-destructive testing CY - Metz, France DA - 05.06.2019 KW - Additive manufacturing KW - Laser metal deposition KW - Thermography KW - Optical emission spectroscopy KW - Process monitoring PY - 2019 AN - OPUS4-48228 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Straße, Anne A1 - Scheuschner, Nils A1 - Altenburg, Simon A1 - Pignatelli, Giuseppe A1 - Baensch, Franziska A1 - Gornushkin, Igor B. A1 - Meierhofer, Christiane A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - In-situ Prozessüberwachung beim Laser-Pulver-Auftragschweißen (LPA) mittels Thermographie, optischer Emissionsspektroskopie (OES) und Schallemission (AE) N2 - In diesem Vortrag wird ein Überblick über die in-situ Messverfahren gegeben, die im Rahmen des Projektes ProMoAM an der LPA- Anlage eingesetzt wurden. Im Speziellen sind das die Thermographie, die optische Emissionsspektroskopie (OES) und die Akustische Emission (AE). T2 - 41. Assistentenseminar der WGF e.V. CY - Online meeting DA - 02.09.2020 KW - Schallemission KW - Laser-Pulver-Auftragschweißen KW - Thermographie KW - Optische Emissionsspektroskopie PY - 2020 AN - OPUS4-51273 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Straße, Anne A1 - Gumenyuk, Andrey A1 - Scheuschner, Nils A1 - Altenburg, Simon A1 - Pignatelli, Giuseppe A1 - Gornushkin, Igor B. A1 - Baensch, Franziska A1 - Rethmeier, Michael T1 - In-situ Prozessüberwachung beim Laser-Pulver-Auftragschweißen (LPA) mittels Thermografie, optischer Emissionsspektroskopie (OES) und Schallemissionsanalyse (SEA) N2 - Vor allem in den letzten Jahren ist das Interesse der Industrie an der additiven Fertigung deutlich gestiegen. Die Vorteile dieser Verfahren sind zahlreich und ermöglichen eine ressourcenschonende, kundenorientierte Fertigung von Bauteilen, welche zur stetigen Entwicklung neue Anwendungsbereiche und Werkstoffe führen. Aufgrund der steigenden Anwendungsfälle, nimmt auch der Wunsch nach Betriebssicherheit unabhängig von anschließenden kostenintensiven zerstörenden und zerstörungsfreien Prüfverfahren zu. Zu diesem Zweck werden im Rahmen des von der BAM durchgeführten Themenfeldprojektes „Prozessmonitoring in Additive Manufacturing“ verschiedenste Verfahren auf ihre Tauglichkeit für den in-situ Einsatz bei der Prozessüberwachung in der additiven Fertigung untersucht. Hier werden drei dieser in-situ Verfahren, die Thermografie, die optische Emissionsspektroskopie und die Schallmissionsanalyse für den Einsatz beim Laser-Pulver-Auftragschweißen betrachtet. T2 - 41. Assistentenseminar der Füge- und Schweißtechnik CY - Magdeburg, Germany DA - 02.09.2020 KW - Laser-Pulver-Auftragschweißen (LPA) KW - Thermographie KW - Optische Emissionsspektroskopie (OES) KW - Schallemissionsanalyse (SEA) PY - 2021 SN - 978-3-96144-141-9 VL - 370 SP - 132 EP - 140 PB - DVS MEdia CY - Düsseldorf AN - OPUS4-53967 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Eddah, Mustapha A1 - Markötter, Henning A1 - Mieller, Björn A1 - Beckmann, Jörg A1 - Bruno, Giovanni T1 - Synchrotron Multi-energy HDR tomography for LTCC systems N2 - LTCCs (Low-temperature co-fired ceramics) consist of three-dimensionally distributed, hermetically bonded ceramic and metallic components with structure sizes within [10; 100] µm. A non-destructive imaging technique is needed that provides 3D, sharp, high-contrast resolution of these structures, as well as porosity and defect analysis, which is made difficult by the very different X-ray absorption coefficients of the individual components of the microstructure. A HDR method is being developed that allows a combination of different tomograms, each with X-ray energies adapted to individual materials. T2 - Bessy II User Meeting CY - Berlin, Germany DA - 22.06.2023 KW - LTCC KW - Synchrotron tomography KW - Data fusion KW - In-situ tomography PY - 2023 AN - OPUS4-57795 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Geyler, Paul A1 - Rabe, Torsten A1 - Mieller, Björn A1 - Léonard, Fabien T1 - Machine learning assisted evaluation of the shape of VIAs in a LTCC multilayer N2 - The introduction of the 5G technology and automotive radar applications moving into higher frequency ranges trigger further miniaturization of LTCC technology (low temperature co-fired ceramics). To assess dimensional tolerances of inner metal structures of an industrially produced LTCC multilayer, computer tomography (CT) scans were evaluated by machine learning segmentation. The tested multilayer consists of several layers of a glass ceramic substrate with low resistance silver-based vertical interconnect access (VIA). The VIAs are punched into the LTCC green tape and then filled with silver-based pastes before stacking and sintering. These geometries must abide by strict tolerance requirements to ensure the high frequency properties. This poster presents a method to extract shape and size specific data from these VIAs. For this purpose, 4 measurements, each containing 3 to 4 samples, were segmented using the trainable WEKA segmentation, a non-commercial machine learning tool. The dimensional stability of the VIA can be evaluated regarding the edge-displacement as well as the cross-sectional area. Deviation from the ideal tubular shape is best measured by aspect ratio of each individual layer. The herein described method allows for a fast and semi-automatic analysis of considerable amount of structural data. This data can then be quantified by shape descriptors to illustrate 3-dimensional information in a concise manner. Inter alia, a 45 % periodical change of cross-sectional area is demonstrated. T2 - DKG Jahrestagung 2019 CY - Leoben, Austria DA - 06.05.2019 KW - Machine Learning KW - LTCC multilayer KW - 5G PY - 2019 AN - OPUS4-48289 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Scheuschner, Nils A1 - Altenburg, Simon A1 - Straße, Anne A1 - Gumenyuk, Andrey A1 - Maierhofer, Christiane T1 - In-situ thermographic monitoring of the laser metal deposition process N2 - By allowing economic on demand manufacturing of highly customized and complex workpieces, metal based additive manufacturing (AM) has the prospect to revolutionize many industrial areas. Since AM is prone to the formation of defects during the building process, a fundamental requirement for AM to become applicable in most fields is the ability to guarantee the adherence to strict quality and safety standards. A possible solution for this problem lies in the deployment of various in-situ monitoring techniques. For most of these techniques, the application to AM is still very poorly understood. Therefore, the BAM in its mission to provide safety in technology has initiated the project “Process Monitoring of AM” (ProMoAM). In this project, a wide range of in-situ process monitoring techniques, including active and passive thermography, optical tomography, optical emission and absorption spectroscopy, eddy current testing, laminography, X-ray backscattering and photoacoustic methods, are applied to laser metal deposition (LMD), laser powder bed fusion and wire arc AM. Since it is still unclear which measured quantities are relevant for the detection of defects, these measurements are performed very thoroughly. In successive steps, the data acquired by all these methods is fused and compared to the results of reference methods such as computer tomography and ultrasonic immersion testing. The goal is to find reliable methods to detect the formation of defects during the building process. The detailed acquired data sets may also be used for comparison with simulations. Here, we show first results of high speed (> 300 Hz) thermographic measurements of the LMD process in the SWIR range using 316L as building material. For these experiments, the camera was mounted fixed to the welding arm of the LMD machine to keep the molten pool in focus, regardless of the shape of the specimen. As the thermograms do not contain any information about the current spatial position during the building process, we use an acceleration sensor to track the movement and synchronize the measured data with the predefined welding path. This allows us to reconstruct the geometry of the workpieces and assign the thermographic data to spatial positions. Furthermore, we investigate the influence of the acquisition wavelength on the thermographic data by comparing measurements acquired with different narrow bandpass filters (50 nm FWHM) in a spectral range from 1150 nm to 1550 nm. This research was funded by BAM within the Focus Area Materials. T2 - Sim-AM 2019 - 2. International Conference on Simulation for Additive Manufacturing CY - Pavia, Italy DA - 11.09.2019 KW - Additive manufacturing KW - 3D printing KW - Thermography KW - Direct energy deposition KW - Laser Metal Deposition KW - 3D Druck KW - Laser Pulver Auftragsschweißen KW - Additive Fertigung KW - Thermografie PY - 2019 AN - OPUS4-49070 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hönig, Gerald A1 - Schlichting, S. A1 - Wagner, M. R. A1 - Müssener, J. A1 - Hill, P. A1 - Grieb, T. A1 - Teubert, J. A1 - Schörmann, J. A1 - Rosenauer, A. A1 - Eickhoff, M. A1 - Hoffmann, A. A1 - Callsen, G. T1 - QCSE tuning in polar GaN/AlN heterostructures N2 - We show both theoretically and experimentally how the encapsulation of the active region by additional guard layers can be used to achieve a significant reduction of the built-in electric fields in polar nitride heterostructures. This reduction of the QCSE results in a strongly enhanced emission intensity and faster recombination dynamics in the active region. In particular we are able to shift the emission energy of 4-nm-thick GaN nano-discs up to 3.32 eV, which is just 150 meV below the bulk GaN bandgap as compared to a red-shift of about 1 eV in a conventional heterostructure with the same thickness. T2 - SPIE. PHOTONICS WEST OPTO CY - San Francisco, CA, USA DA - 29.01.2018 KW - QCSE KW - Piezopolarization KW - Spontaneous Polarization KW - IFGARD KW - Nanoheterostructures KW - Nonpolar PY - 2018 AN - OPUS4-43383 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shapovalov, Oleg A1 - Gaal, Mate A1 - Hönig, Gerald A1 - Gradt, Thomas A1 - Weiss, S. T1 - Temperature dependence of the propagation speed of a longitudinal wave in different solids for use as a wedge material in an extreme-temperature-resistant ultrasonic transducer N2 - In special cases of angle beam ultrasonic measurement – e.g. defect detection in hot solids as well as flow measurement of liquid gases or energy storage mediums – the applied transducer has to withstand extreme temperatures. Since the irradiation angle into the specific material is determined not only by wedge design, but also by the speed of sound in both the wedge material and the tested object, the developer must take into account the speed of the wave propagation in a wedge material over the whole temperature range of transducers application. In this study we investigate the temperature dependence of the speed of longitudinal wave propagation in 10 different materials in the range from -200 °C to 400 °C. The investigated materials belong to different material classes (ceramics, glass, as well as ferrous and non-ferrous metals) and are all temperature-resistant up to at least 600 °C, and therefore applicable as wedge materials in an ultrasonic transducer for use at extreme temperatures. T2 - 23rd International Congress on Acoustics CY - Aachen, Germany DA - 09.09.2019 KW - Ultrasonic Transducer KW - Speed of sound KW - Longitudinal Wave KW - Temperature PY - 2019 SP - 4776 EP - 4782 AN - OPUS4-48980 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shapovalov, Oleg A1 - Gaal, Mate A1 - Hönig, Gerald A1 - Gradt, Thomas A1 - Weiss, S. T1 - Temperature dependence of the propagation speed of a longitudinal wave in different solids for use as a wedge material in an extreme temperature resistant ultrasonic transducer N2 - In special cases of angle beam ultrasonic measurement the applied transducer has to withstand extreme temperatures. Since the irradiation angle depends on the speed of sound in both the wedge material and the tested object, the developer must take into account the speed of Sound in a wedge material over the whole temperature range of transducers application. T2 - 23rd International Congress on Acoustics CY - Aachen, Germany DA - 09.09.2019 KW - Ultrasonic Transducer KW - Speed of sound KW - Longitudinal Wave KW - Temperature PY - 2019 AN - OPUS4-48982 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mrkwitschka, Paul A1 - Mieller, Björn A1 - Rabe, Torsten A1 - Markötter, Henning T1 - Machine learning assisted characterization of a Low Temperature Co-fired Ceramic (LTCC) module measured by synchrotron computed tomography. N2 - The 5G technology promises real time data transmission for industrial processes, autonomous driving, virtual and augmented reality, E-health applications and many more. The Low Temperature Co-fired Ceramics (LTCC) technology is well suited for the manufacturing of microelectronic components for such applications. Still, improvement of the technology such as further miniaturization is required. This study focuses on the characterization of inner metallization of LTCC multilayer modules, especially on the vertical interconnect access (VIA). Critical considerations for this characterization are delamination, pore clustering in and at the edge of the VIA, deformation, and stacking offset. A LTCC multilayer consisting of a glassy crystalline matrix with silver based VIAs was investigated by synchrotron x-ray tomography (CT). The aim of this study is to propose a multitude of structural characteristic values to maximize the information gained from the available dataset. Data analysis has been done with the open source software ImageJ as well as several additional plugins. The high-resolution CT data was evaluated through 2D slices for accessibility reasons. The segmentation of all 2000 slices to assess the different regions e.g. pores, silver and glass ceramic was done by a supervised machine learning algorithm. A quantitative evaluation of shape, deformation, and porosity of the VIA with respect to its dimensions is presented and the suitability of the characterization approach is assessed. T2 - 54. Metallographie Tagung CY - Online meeting DA - 16.09.2020 KW - Machine Learning KW - LTCC KW - Synchrotron Tomography PY - 2020 AN - OPUS4-51299 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ziegler, Mathias A1 - Maierhofer, Christiane A1 - Krankenhagen, Rainer A1 - Röllig, Mathias T1 - Characterization of defects in fibre reinforced composites (FRC) using passive and active thermography N2 - Impact damages and delaminations in fibre-reinforced composites (FRC) might not be visible at the surface, but could have an influence on the resistance and on the long-term behaviour of the component. Therefore, and especially for safety relevant structures, non-destructive methods are required for the assessment of such damages. Active thermography methods are suitable to characterize damages after loading using different kind of excitation techniques and various configurations of infrared (IR) camera and heating sources. Here, flash lamps, impulse excitation with infrared radiator and lock-in technique with halogen lamps or widened laser beams are suited. In addition, non-optical sources like sonotrodes (requiring direct contact to the structure) or induction generators (only suited for carbon fibre reinforced polymer (CFRP) structures) could be applied as well. For the investigation of the evolution of the damage during the impact, passive thermography can be applied in-situ. Elastic and plastic deformations alter the temperature of the structure and thus the temperature on the surface. In this contribution, at first the general principles of quantitative defect characterisation in FRC using active thermography with flash, impulse and lock-in excitation are described. Optical and thermal properties of the FRC material and its anisotropy are considered. Results of phase differences obtained at flat bottom holes with flash and lock-in thermography are compared for qualifying both methods for quantitative defect characterization. Secondly, the damage evolution of CFRP and GFRP structures under impact load and static tensile loading is described. The spatial and temporal evolution of the surface temperature enables us to distinguish matrix cracks or fibre-matrix separation from delaminations between the layers. Afterwards, all results for loading defects, obtained by passive and active thermography, are compared with each other. Fig. 1 and 2 show the difference of passive and flash thermography obtained at impact and tensile loaded CFRP plates, respectively. As one purpose of these investigations is the development of standards within national (DIN) and European (CEN) standardisation bodies, new draft and final standards are presented and further needs are discussed at the end of the presentation. T2 - INTERNATIONAL SCHOOL OF QUANTUM ELECTRONICS, 62nd Course, Progress in Photoacoustic & Photothermal Phenomena CY - Erice, Italy DA - 06.09.2018 KW - Thermography KW - Flash thermography KW - Lock-in thermography KW - CFRP KW - GFRP PY - 2018 AN - OPUS4-46283 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pittner, Andreas A1 - Winterkorn, René A1 - Fabry, Çağtay A1 - Rethmeier, Michael A1 - Ulbricht, Alexander A1 - Bruno, Giovanni T1 - Additive Manufacturing of High Strength Al-Mg-Si Alloys with DED-Arc N2 - Direct energy deposition additive manufacturing technologies that utilize an electric arc have great potential for generating large volume metal components. However, selecting process parameters that yield the desired near net shape design and requested mechanical component behavior is not a trivial task due to the complex relationship between all process parameters and material characteristics. This presentation exemplifies the application of a newly developed solid welding wire doped with TiB to enhance grain refinement in the deposited metal for additive manufacturing based on DED-Arc of high-strength precipitation hardening AlMgSi-aluminum alloys. It is worth noting that the solid wire is the result of our preliminary metallurgical studies on grain refinement in aluminum weld metal. Consequently, research focuses on the correlation between process parameters and component quality to understand the underlying mechanisms. This is crucial for evaluating a robust process parameter space that yields component quality in line with corresponding standards which are mainly taken from welding technology. Specifically, we examine component quality by analyzing pore size and distribution, as well as grain morphology. To enhance the mechanical properties of the deposited metal, a post-weld heat treatment was conducted, comprising of solution treatment, quenching, and artificial aging. The study also evaluates the effects of various heat treatment strategies on the final mechanical properties of the material. To demonstrate the applicability of 3D metal printing of high-strength aluminium alloys, a more complex demonstrator was created. It has been shown that DED-Arc can produce high-volume aluminium parts with the same quality as the corresponding subtractive processing strategy. Additionally, the entire additive manufacturing chain has been digitally integrated, enabling traceability of all relevant process steps, which is essential for reliable subsequent quality assessment. T2 - 4th Symposium on Materials and Additive Manufacturing - Additive 2024 CY - Berlin, Germany DA - 12.06.2024 KW - DED-Arc KW - High-stength aluminium alloys KW - Grain refinement KW - Quality assurance PY - 2024 AN - OPUS4-60248 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Maack, Stefan A1 - Benner, Philipp A1 - Kröll, Mirco A1 - Prager, Jens A1 - Daum, Werner A1 - Casperson, Ralf A1 - Heckel, Thomas A1 - Spaltmann, Dirk A1 - et al., ED - Wahlster, W. ED - Winterhalter, C. T1 - Deutsche Normungsroadmap künstliche Intelligenz T1 - German standardization roadmap on artificial intelligence N2 - Im Auftrag des Bundesministeriums für Wirtschaft und Klimaschutz haben DIN und DKE im Januar 2022 die Arbeiten an der zweiten Ausgabe der Deutschen Normungsroadmap Künstliche Intelligenz gestartet. In einem breiten Beteiligungsprozess und unter Mitwirkung von mehr als 570 Fachleuten aus Wirtschaft, Wissenschaft, öffentlicher Hand und Zivilgesellschaft wurde damit der strategische Fahrplan für die KI-Normung weiterentwickelt. Koordiniert und begleitet wurden diese Arbeiten von einer hochrangigen Koordinierungsgruppe für KI-Normung und -Konformität. Mit der Normungsroadmap wird eine Maßnahme der KI-Strategie der Bundesregierung umgesetzt und damit ein wesentlicher Beitrag zur „KI – Made in Germany“ geleistet. Die Normung ist Teil der KI-Strategie und ein strategisches Instrument zur Stärkung der Innovations- und Wettbewerbsfähigkeit der deutschen und europäischen Wirtschaft. Nicht zuletzt deshalb spielt sie im geplanten europäischen Rechtsrahmen für KI, dem Artificial Intelligence Act, eine besondere Rolle. N2 - On behalf of the German Federal Ministry of Economic Affairs and Climate Action, DIN and DKE started work on the second edition of the German Standardization Roadmap Artificial Intelligence in January 2022. With the broad participation and involvement of more than 570 experts from industry, science, the public sector and civil society, the strategic Roadmap for AI standardization was thus further developed. This work was coordinated and accompanied by a high-level coordination group for AI standardization and conformity. The standardization roadmap implements a measure of the German government’s AI Strategy and thus makes a significant contribution to “AI – Made in Germany”. Standardization is part of the AI Strategy and is a strategic instrument for strengthening the innovation and competitiveness of the German and European economies. Not least for this reason, standardization plays a special role in the planned European legal framework for AI, the Artificial Intelligence Act. KW - Digitalisierung KW - Künstliche Intelligenz KW - Datenwissenschaft KW - Normung Roadmap KW - Data science KW - Artificial intelligence KW - Standardization roadmap KW - Digitization PY - 2022 UR - https://www.din.de/resource/blob/1072988/20bf33d405710a703aa26f81362493bb/ausgabe-2-nrm-ki-data.pdf UR - https://www.dke.de/de/arbeitsfelder/core-safety/normungsroadmap-ki SP - 1 EP - 448 PB - Deutsches Institut für Normung (DIN) CY - Berlin ET - 2. AN - OPUS4-56576 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Maack, Stefan A1 - Bertovic, Marija A1 - Radtke, Martin A1 - et al., ED - Wahlster, W. ED - Winterhalter, C. T1 - Deutsche Normungsroadmap künstliche Intelligenz N2 - Rund ein Jahr haben DIN und DKE in einem gemeinsamen Projekt mit dem Bundesministerium für Wirtschaft und Energie und zusammen mit ca. 300 Fachleuten aus Wirtschaft, Wissenschaft, öffentlicher Hand und Zivilgesellschaft an der Normungsroadmap Künstliche Intelligenz gearbeitet. Eine hochrangige Steuerungsgruppe unter dem Vorsitz von Prof. Wolfgang Wahlster hat die Erarbeitung koordiniert und begleitet. Ziel der Roadmap ist die frühzeitige Entwicklung eines Handlungsrahmens für die Normung und Standardisierung, der die internationale Wettbewerbsfähigkeit der deutschen Wirtschaft unterstützt und europäische Wertmaßstäbe auf die internationale Ebene hebt. KW - Künstliche Intelligenz KW - Normung KW - Roadmap PY - 2020 UR - https://www.din.de/resource/blob/772438/ecb20518d982843c3f8b0cd106f13881/normungsroadmap-ki-data.pdf VL - 2020 SP - 1 EP - 232 PB - Deutsches Institut für Normung (DIN) CY - Berlin ET - 1. AN - OPUS4-51733 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Ziegler, Mathias A1 - Altenburg, Simon A1 - Krankenhagen, Rainer A1 - Maierhofer, Christiane A1 - Scheuschner, Nils A1 - Marquardt, E A1 - Mühlberger, W. A1 - Nagel, F. A1 - Neumann, E. A1 - Rohwetter, P. A1 - Rutz, F. A1 - Schwake, C. A1 - Schramm, S. A1 - Schwaneberg, F. A1 - Taubert, R. D. T1 - Thermografie und Strahlungsthermometrie - Stand und Trends N2 - In vielen Umgebungen, besonders bei hohen Temperaturen, korrosiven Umgebungen oder auf bewegten oder schlecht zugänglichen Flächen, kann die Temperatur nicht oder nur mit nicht akzeptablem Aufwand mit Berührungsthermometern gemessen werden. Diese Umgebungsbedingungen sind unter anderem in der chemischen Industrie, der Lebensmittel-, Metall-, Glas-, Kunststoff- und Papierherstellung sowie bei der Lacktrocknung anzutreffen. In diesen Bereichen kommen Strahlungsthermometer zum Einsatz. Der VDI-Statusreport zeigt typische Anwendungsfelder von nicht radiometrisch kalibrierten Wärmebildkameras und von radiometrisch kalibrierten Thermografiekameras. Um verlässlich mit spezifizierten Messunsicherheiten berührungslos Temperaturen zu messen, müssen die Strahlungsthermometer und Thermografiekameras nicht nur kalibriert, sondern radiometrisch und strahlungsthermometrisch umfassend charakterisiert werden. Auch die optische Materialeigenschaft, der spektrale Emissionsgrad und die Gesamtstrahlungsbilanz (Strahlung des Messobjekts und der Umgebung) sind bei der industriellen Temperaturmessung von großer Bedeutung. In den letzten Jahrzehnten ist dazu ein umfassendes technisches Regelwerk entstanden, das wir Ihnen mit diesem VDI-Statusreport vorstellen. Manche in den Richtlinien beschriebenen Kennwerte mögen abstrakt wirken. In diesem Statusreport zeigen wir an konkreten Beispielen, was diese Kenngrößen für die berührungslose Temperaturmessung bedeuten. Beispiele von Anwendungen zeigen, wo temperaturmessende Thermografiekameras und ausschließlich bildgebende Wärmebildkameras in der Praxis eingesetzt werden. Mit einer Analyse, welche Themen und Anwendungen derzeit besonders intensiv diskutiert werden, versuchen wir Trends für zukünftige Entwicklungen herauszuarbeiten. KW - Thermografie KW - Temperaturmessung PY - 2021 UR - https://www.vdi.de/ueber-uns/presse/publikationen/details/thermografie-und-strahlungsthermometrie-stand-und-trends SP - 1 EP - 40 PB - VDI Verein Deutscher Ingenieure e.V. CY - Düsseldorf AN - OPUS4-52904 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Breese, Philipp Peter A1 - Becker, Tina A1 - Oster, Simon A1 - Metz, C. A1 - Altenburg, Simon J. T1 - In-situ defect detection for laser powder bed fusion with active laser thermography N2 - Defects are still common in metal components built with Additive Manufacturing (AM). Process monitoring methods for laser powder bed fusion (PBF-LB/M) are used in industry, but relationships between monitoring data and defect formation are not fully understood yet. Additionally, defects and deformations may develop with a time delay to the laser energy input. Thus, currently, the component quality is only determinable after the finished process. Here, active laser thermography, a nondestructive testing method, is adapted to PBF-LB/M, using the defocused process laser as heat source. The testing can be performed layer by layer throughout the manufacturing process. We study our proposed testing method along experiments carried out on a custom research PBF-LB/M machine using infrared (IR) cameras. Our work enables a shift from post-process testing of components towards in-situ testing during the AM process. The actual component quality is evaluated in the process chamber and defects can be detected between layers. T2 - 2023 International Solid Freeform Fabrication Symposium CY - Austin, TX, USA DA - 14.08.2023 KW - Additive Manufacturing KW - Laser Powder Bed Fusion KW - Nondestructive Testing KW - Thermography KW - Defect Detection PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-606288 DO - https://doi.org/10.26153/tsw/51096 SP - 1978 EP - 1989 PB - University of Texas at Austin CY - Austin, TX, USA AN - OPUS4-60628 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -