TY - CONF A1 - Hille, Falk A1 - Schneider, Ronald A1 - Simon, Patrick A1 - Herrmann, Ralf A1 - Baeßler, Matthias ED - Döhler, Michael ED - Mélot, Adrien ED - Aenlle Lopez, Manuel T1 - System identification and model calibration of a steel road bridge N2 - The Bundesanstalt für Materialforschung und -prüfung (BAM), in cooperation with the Netherlands Organization for Applied Scientific Research (TNO), is working on a framework for integrating frequently updated structural models into an asset management process for bridge structures. A multi-span steel road bridge was selected as a test case for the development of this framework. In order for the structural model to represent the real behavior of the bridge with sufficient accuracy, model calibration is required. In this case, we have planned to calibrate the model based on the dynamic response of the bridge. To determine its dynamic properties, a multi-setup operational modal analysis was performed on one of the bridge spans. In parallel, a structural model of the span was developed based on the available design and service life information. Both eigenfrequencies and mode shapes were used as reference parameters to calibrate the model. A sensitivity analysis was performed to identify the most influential design parameters. Subsequently, a genetic algorithm was applied for minimizing the difference between measured and simulated characteristic responses. In the proposed paper, we summarize the measurements as well as the determination of the modal response of the bridge and describe the process of calibration of the structural model using the identified dynamic response. T2 - 11th International Operational Modal Analysis Conference (IOMAC 2025) CY - Rennes, France DA - 20.05.2025 KW - Bridge structure KW - Operational modal analysis KW - Model calibration PY - 2025 SN - 978-84-09-75120-4 SP - 114 EP - 121 PB - International Group of Operational Modal Analysis CY - Gijón, Spain AN - OPUS4-64416 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz A1 - Said, Samir A1 - Rohrmann, Rolf ED - Döhler, Michael T1 - Modal analysis of road and rail bridges for damage detection and resonance prediction N2 - In the 1980s, the Federal Institute of Material Research and Testing started with modal analysis measurements of some bridges before and after repair. For one of the bridges, a structural health monitoring was installed 1994 which is still working up to now. It has been modified and extended several times. The monitoring was extended from the critical span to three neighbouring spans. A modal analysis of the whole bridge with seven spans have been done three times, twice together with EMPA of Switzerland. Additional calibration measurements have been done and additional evaluation procedures have been implemented for the monitoring of the steadily increasing loads from the road traffic. Additional sensors were installed such as strain gauges, crack-width, and temperature sensors. The strong influence of the temperature on the natural frequencies has been studied over the years. Later, a temperature compensation has been established and a weak aging trend has been found in the monitoring data. Now, the bridge will be demolished and replaced by a new bridge. Some results of this long-term monitoring will be shown and possible damages (changes of the pre-stress or the support structure) will be discussed. A second application of modal analysis will be demonstrated: the prediction of the resonances due to passing trains. The response of a bridge to passing trains can be calculated in frequency domain as the multiplication of three spectra, the axle sequence spectrum of the train, the transfer function of the bridge, and the modal force spectrum of a single passing load. A resonance occurs if a maximum of the train spectrum coincides with the maximum of the bridge spectrum. The amplitude at this resonance is strongly influenced by the modal force spectrum which is identical to the frequency or wavenumber spectrum of the corresponding mode shape. Therefore, modal analysis from calculation, impact measurements, wind and train measurements are necessary for the prediction of the resonance occurrence and amplification. Examples of mode shape spectra for single or multi-span bridges with simply supported or continuous spans will be shown, and some relations between mode shapes and resonance amplifications will be concluded. T2 - 11th International Operational Modal Analysis Conference (IOMAC) CY - Rennes, France DA - 20.05.2025 KW - Bridge monitoring KW - Multi-span bridges KW - Damage detection KW - Resonance PY - 2025 SP - 39 EP - 46 PB - INRIA CY - Rennes AN - OPUS4-63473 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz A1 - Song, Jiaojiao T1 - Analysis of intact and damaged (floating) slab tracks by finite-element boundary-element models and by measurements N2 - The damage detection and repair control have become important tasks for slab tracks. Different intact and damaged slab tracks have been investigated theoretically and experimentally for train passages and hammer impacts. The following damages have been considered: The loss of contact between the sleeper and the track slab, between the track slab and the base slab, and between the base slab and the base layer. At first, a slab track with a gap between the track slab and the base layer has been calculated by the combined finite-element boundary-element method which correctly incorporates the behaviour of the infinite soil. The basic results are the track displacements of the rail, the track slab, and the base layer along the track which are caused by a single axle load. These solutions are properly superposed for to get the complete train load. The influence of track and soil parameters and of the track damage has been analysed. For the intact track, the compliance of the soil is dominant whereas the track bending stiffness becomes more important for the damaged track. By comparing the calculated results with the measurements, the length of the gap could be quantified. A slab track with a loose sleeper (without contact to the supporting track slab) was analysed by the transfer function between the displacements and the hammer force (receptance functions) where a resonance appeared in case of the damage. Differences between the different track elements confirmed the detection of the damage. A floating slab track with a thin rubber layer has been investigated for a possible gap between the base slab and the base layer. The behaviour of the intact track has been calculated by a wavenumber-domain method, and the same behaviour has been found in the measurements at several track sections, indicating that there is no damage. Finally, a floating slab track with steel springs and viscous fluid dampers has been measured in the Tongji laboratory. The modes of the floating track slab and the transfer function with corresponding resonances have been calculated and successfully compared with results from wheelset drop tests. T2 - Third International Conference on Rail Transportation (ICRT2024) CY - Shanghai, China DA - 07.08.2024 KW - Railway track KW - Damage KW - Vibration measurement KW - Finite element method KW - Boundary element method KW - Frequency response function KW - Moving load response KW - Floating slab track PY - 2025 SN - 978-0-7844-8594-1 SP - 591 EP - 600 AN - OPUS4-61267 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Thoralf A1 - Lehmann Schlag, Jens A1 - Burkert, Andreas T1 - KorroPad®-Ein Kurzzeitprüfverfahren zur Qualitätssicherung der Oberflächen- und Schweißnahtnachbearbeitung nichtrostender Stähle N2 - Die Ausbildung einer stabilen Passivschicht ist entscheidend für den Korrosionsschutz nichtrostender Stähle. KorroPad® bietet eine schnelle, zerstörungsfreie Bewertung der Passivschichtstabilität und ist seit 2025 als DIN 50024 genormt. Die Methode ermöglicht eine 15‑minütige Vor‑Ort‑Prüfung ohne Spezialwissen und schließt die Lücke zwischen teuren Laborverfahren und fehlender prozessbegleitender Qualitätssicherung. Der Beitrag beschreibt Funktionsprinzip, Anwendung sowie Beispiele aus der Oberflächen- und Schweißnahtbearbeitung. T2 - 43. Vortrags- und Diskussionstagung Werkstoffprüfung 2025 CY - Dresden, Germany DA - 26.11.2025 KW - KorroPad KW - Nichtrostender Stahl KW - Korrosion KW - Passivität PY - 2025 SN - 978-3-88355-454-9 VL - 43 SP - 1 EP - 7 PB - DGM Deutsche Gesellschaft für Materialkunde e.V. CY - Sankt Augustin AN - OPUS4-64933 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Klaus, Christian A1 - Soruco Aloisio, Ricardo A1 - Koch, Claudia A1 - Prellwitz, Matthias T1 - Towards Safety and Accuracy of Hydrogen Refuelling Stations through Digital Twins N2 - This paper presents digital quality infrastructure methods for hydrogen refueling stations using the Asset Administration Shell as a standardized digital twin. Implemented at BAM’s test platform, it integrates real-time sensor data, calibration certificates, and compliance documents to support traceable, interoperable asset management. In combination with AI and semantic tools, the system will enable predictive maintenance, remote audits, and improved safety. This approach reduces downtime, enhances transparency, and offers a scalable model demonstrating the potential of digital twins in advancing metrological traceability and operational efficiency in hydrogen technologies. T2 - IMEKO TC-6 International Conference on Metrology and Digital Transformation - M4DConf 2025 CY - Benevento, Italy DA - 03.09.2025 KW - Datenintregration KW - IT KW - Verwaltungsschale KW - Infrastruktur KW - OT KW - Open Source KW - Software PY - 2025 UR - https://www.m4dconf.org/ UR - https://www.sciencedirect.com/journal/measurement-digitalization SP - 1 EP - 6 AN - OPUS4-64951 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Grohmann, Maria A1 - Niederleithinger, Ernst T1 - Application of Elastic Reverse Time Migration to Ultrasonic Echo Data from Concrete Structures N2 - To enhance ultrasonic imaging of concrete structures, we adapted the geophysical migration method, Reverse Time Migration (RTM), for non-destructive testing (NDT) in civil engineering. First, two 2D elastic RTM algorithms, each considering different wave types, were implemented and evaluated with synthetic ultrasonic data. The algorithm that best resolved numerical concrete structures was subsequently applied to real ultrasonic data from a concrete specimen. Compared with conventional synthetic aperture focusing technique (SAFT) imaging, elastic RTM reproduced a greater number of structural features in both the numerical model and the concrete specimen. In particular, elastic RTM reconstructed vertical interfaces as well as hidden lower edges of modeled cavities and tendon ducts. Notably, imaging the full cross-sections of tendon ducts, which enables direct diameter estimation, represents a novel achievement for ultrasonic NDT. T2 - NDT-CE 2025 - The International Symposium on Nondestructive Testing in Civil Engineering CY - Izmir, Turkey DA - 24.09.2025 KW - Concrete Structures KW - Ultrasonic Echo Technique KW - Ultrasonic Imaging KW - Elastic Reverse Time Migration KW - Synthetic Aperture Focusing Technique PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-650350 DO - https://doi.org/10.58286/31680 SN - 1435-4934 SP - 1 EP - 3 PB - e-Journal of Nondestructive Testing CY - www.ndt.net AN - OPUS4-65035 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mair, Georg W. A1 - Günzel, Stephan A1 - Bock, Robert T1 - Risk management and consequence control in hydrogen transport - volume dependent pressure limitation as a scientific approach for consequence control N2 - With technological development, the transport units for compressed gases are becoming larger and their number is increasing. Simultaneously, the filling pressure for hydrogen in transport has increased far beyond the 200 bar, which has been the common European standard for decades. In total, this increases the potential consequences of an incident, which needs to get limited for ensuring acceptance in current practice with pressure vessels from large serial production. Consequently, the measures for new developments of extremely large and highly pressurised pressure vessels should meet a risk based higher level of requirements. For this purpose, the so-called pressure-volume product was proposed as a safety related criteria to the relevant regulatory bodies in 2020. The approach was accepted, and a working group was set up at the United Nations for developing a broadly accepted limitation of today's established pressure vessels compared to future units with even more gas content. The path to the finally decided limit value of 1.5 million bar litres is presented here for hydrogen with its individual steps: ‘Boundary between major accident and disaster’, ‘The effect of pressure waves on the human body’, ‘The propagation of pressure waves’, ‘The reference value for population density’ and ‘Impact of pressure waves’. This result of the UN working group has been accepted in December 2023 and will lead to a binding limitation of the pressure volume product for the so called pressure receptacles by 2027. The work on units larger than this pV-limit is going on at ISO level. T2 - 11th International Conference on Hydrogen Safety ICHS 2025 CY - Seoul, South Korea DA - 22.09.2025 KW - Safety KW - Hydrogen transport KW - Major accident KW - Pressure wave KW - Population density KW - UN Model Regulations PY - 2025 SP - 1 EP - 14 AN - OPUS4-64199 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nattuveettil, Keerthana A1 - Liebner, Christian A1 - Tiebe, Carlo T1 - Hydrogen safety- Dealing with Closed Spaces N2 - Hydrogen is under discussion as a potentially clean energy source, but its safe usage and handling in enclosed environments remains a critical challenge due to the properties of hydrogen. This work focuses on detecting and monitoring hydrogen concentration in closed spaces to improve safety by developing a sensor network-based leak detection system to prevent of the accumulation of hazardous mixtures. Furthermore, the study details the implementation of a hydrogen sensor network within a container, analysing sensor placement, data collection, and safety improvements. The findings contribute to better risk assessment and enhanced safety protocols in hydrogen storage and usage facilities. T2 - SMSI 2025 CY - Nuremberg, Germany DA - 06.05.2025 KW - Sensor Network KW - Hydrogen safety KW - QI-Digital PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-640630 SN - 978-3-910600-06-5 DO - https://doi.org/10.5162/SMSI2025/C6.2 SP - 167 EP - 168 PB - AMA Verband für Sensorik und Messtechnik e.V. CY - Berlin AN - OPUS4-64063 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Klippel, Andrea A1 - Hofmann-Böllinghaus, Anja A1 - Heydick, Lukas A1 - Piechnik, Kira A1 - Wu, Hongyi A1 - Köhler, Florian T1 - Experimental Analysis of Fire Behaviour in Pine Forests and Agricultural Fields Large Scale Tests conducted within the TREEADS Project N2 - In two large-scale tests fire spread mechanisms in vegetation ground fires were studied in a pine forest and a crop field. Both fires were ignited with a drip torch using a gasoline-diesel mix. The tests were part of the European TREEADS project, specifically in the research work from the German Pilot focusing on Saxony-Anhalt and Brandenburg. These regions are known for dry, sandy soil, with pine trees covering approximately 73% of forested areas in Brandenburg and 48% in Saxony-Anhalt. The results of both experiments make a substantial contribution to optimizing extinguishing methods and strategies and enhancing a continued wildfire research in Germany. The test areas included a 16 x 22 m plot in a Saxony-Anhalt pine forest and a 20 x 100 m plot on a crop field, with fires ignited along a line using a drip torch at both locations. Fire spread was monitored with video and IR cameras mounted on a drone. In the pine forest, 96 thermocouples and gas sensors were attached to trees and a mobile FTIR spectrometer was used for real-time gas measurements. A protective strip was created around the test area using a soil tiller and fire-retardant foam to prevent uncontrolled fire spread. The experiment showed a consistent temperature rise as the fire was ignited and spread. Thermocouple data captured detailed thermal dynamics, while tree-mounted gas sensors recorded significant fluctuations in combustible gases. Real-time gas spectra from the FTIR spectrometer enabled precise smoke analysis. Conducted in stable weather - 23°C, light wind, low soil moisture—this setup improved reproducibility, with a weather station monitoring temperature, humidity and wind conditions to assess fire-environment interactions. After ignition process the fire showed a slow spread and distinct combustion phases. Smouldering was more pronounced in areas with grasses and deadwood, highlighting vegetation-specific burn patterns critical to wildfire research. The experiment showed numerous smouldering and burning spots, with flames igniting and extinguishing repeatedly. However, flame height did not exceed half a meter. Due to substantial smoke production, visibility in the test field was limited and team members wore respirators to collect specific smoke gases such as benzene and formaldehyde for analysis. Field measurements showed flame temperatures exceeding 500°C. Toxic smoke gas concentrations of up to 238 ppm CO were measured, although precise gas capture appeared challenging due to wind turbulence. The second large-scale area in Nauen, a cut wheat field (stubble height approx. 30 cm) was burned, with fire spreading across approximately 700 m². A 20 m ignition line directed flames with the wind. Fire spread was observed using drones equipped with IR cameras. Experiments demonstrated how unpredictable and challenging it is to measure large outdoor fires. To enable a comprehensive theoretical and numerical description of fire dynamics in wildfires, it is essential to conduct further large-scale experiments. T2 - Interflam 2025, 16th International Fire Science and Engineering Conference CY - London, United Kingdom DA - 30.06.2025 KW - Wildfire PY - 2025 SP - 1435 EP - 1444 PB - Interscience CY - London AN - OPUS4-63926 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hofmann-Böllinghaus, Anja A1 - Klippel, Andrea A1 - Piechnik, Kira T1 - Vehicle fires: significant fire hazard in transportation infrastructure N2 - The zeolitic imidazole framework-8 (ZIF-8) is a crystalline porous material that has been widely employed as template to fabricate porous nitrogen-doped carbons with high microporosity via thermal treatment at high temperatures. The properties of the carbon scaffold are influenced by the pore structure and chemical composition of the parent ZIF. However, the narrow pore size distribution and microporous nature from ZIF-8 often results in low mesopore volume, which is crucial for applications such as energy storage and conversion. Here we show that insertion of N-heterocyclic amines can disrupt the structure of ZIF-8 and dramatically impact the chemical composition and pore structure of the nitrogen-doped carbon frameworks obtained after high-temperature pyrolysis. Melamine and 2,4,6-triaminopyrimidine were chosen to modify the ZIF-8 structure owing to their capability to both coordinate metal ions and establish supramolecular interactions. Employing a wide variety of physical characterization techniques we observed that melamine results in the formation of a mixed-phase material comprising ZIF-8, Zn(Ac)6(Mel)2 and crystallized melamine, while 2,4,6-triaminopyrimidine induces the formation of defects, altering the pore structure. Furthermore, the absence of heterocyclic amine in the ZIF-8 synthesis leads to a new crystalline phase, unreported to date. The thermal conversion of the modified ZIFs at 1000 °C leads to nitrogen-doped carbons bearing Zn moieties with increased surface area, mesopore volume and varying degree of defects compared to ZIF-8 derived carbon. This work therefore highlights both the versatility of heterocyclic amines to modify the structure of framework materials as well as their role in tuning pore structure in nitrogen-doped carbons, paving the way to targeted design of high-performance electrodes for energy storage and conversion. T2 - Interflam 2025, 16th International Fire Science and Engineering Conference CY - London, United Kingdom DA - 30.06.2025 KW - Vehicle fires PY - 2025 SP - 1291 EP - 1298 PB - Interscience CY - London AN - OPUS4-63924 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Piechnik, Kira A1 - Hofmann-Böllinghaus, Anja A1 - Klippel, Andrea T1 - Characterization and assessment of smoke emissions from smouldering forest fires: a combined experimental and numerical approach N2 - This article builds upon the publication "Comprehensive Laboratory Study on Smoke Gases During the Thermal Oxidative Decomposition of Forest and Vegetation Fuels"1 in Fire and Materials, 2024, summarizing the experimental methodology and highlighting key findings. The study investigates the gas-phase composition of smoke emissions from forest and vegetation fuels. The study focuses on pine-dominated ecosystems in Eastern Germany, with the objective of improving the understanding of wildfire-related gaseous emissions, as a contribution to the German pilot activities within the EU Project TREEADS. Using a modified DIN tube furnace in a bench-scale setup, the investigation centers on gaseous emissions from five trees and two ground cover species, explicitly excluding particulate matter. T2 - Interflam 2025, 16th International Fire Science and Engineering Conference CY - London, UK DA - 30.06.2025 KW - Wildfire PY - 2025 SP - 288 EP - 294 PB - Interscience CY - London AN - OPUS4-63999 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mente, Tobias A1 - Grimault de Freitas, Tomás A1 - Nietzke, Jonathan A1 - Konert, Florian A1 - Sobol, Oded A1 - Wackermann, Ken A1 - Ruchti, Peter A1 - Elsen-Humberg, Stefan A1 - Systermans, Thomas ED - Zimmermann, Martina T1 - Hohlzugprüfung als kostengünstige Methode zur Werkstoffcharakterisierung für die Wasserstoffwirtschaft N2 - Wasserstoff ist ein notwendiger Baustein zur Erreichung zukünftiger Klimaziele. Für eine schnell hochlaufende Wasserstoffwirtschaft ist es daher notwendig sowohl bestehende Infrastruktur als auch neue Werkstoffe für den sicheren und nachhaltigen Einsatz in Wasserstofftechnologien zu qualifizieren. Die akzeptierten und standardisierten Prüfverfahren zur Ermittlung des Einflusses gasförmigen Wasserstoffs auf die mechanischen Eigenschaften metallischer Werkstoffe sind meist sehr komplex, mit hohem technologischem und finanziellem Aufwand verbunden und stehen nur Wenigen Instituten weltweit zur Verfügung. Die Hohlzugprüftechnik bietet hier eine kostengünstige und einfach zu realisierende Alternative. Mit der im Jahr 2024 erstmals veröffentlichten ISO 7039 wurde diese Prüftechnik auch für die Wirtschaft anwendbar gemacht. Der Standard gilt allgemein für die Prüfung mit gasförmigen Medien, weist jedoch in Bezug auf die Prüfung mit gasförmigem Wasserstoff noch einige Wissenslücken auf. Im Teilvorhaben H2HohlZug des Leitprojekt TransHyDE werden die Lücken zum Einfluss der Geometrie, Oberflächenqualität sowie Gasreinheit in einzelnen Arbeitspaketen geschlossen und die Erkenntnisse in einen Standard überführt. T2 - 43. Vortrags- und Diskussionstagung Werkstoffprüfung 2025 - Werkstoffe und Bauteile auf dem Prüfstand CY - Dresden, Germany DA - 27.11.2025 KW - Hohlzugprüfung KW - Druckwasserstoff KW - ISO 7039 KW - H2HohlZug - TransHyDE PY - 2025 SN - 978-3-88355-454-9 SP - 11 EP - 17 PB - Deutsche Gesellschaft für Materialkunde e.V. (DGM) CY - Dresden AN - OPUS4-64937 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Leo, Reinhold A1 - Sobol, Oded A1 - Hango, Silas Ithete A1 - Saliwan Neumann, Romeo A1 - Askar, Enis A1 - Boellinghaus, Thomas T1 - Ex-situ investigation of the compatibility of Duplex Stainless Steel for high-pressure hydrogen applications N2 - The key to a successful transition into clean energy carriers such as hydrogen requires the construction of safe transportation pipelines made of alloys which are not susceptible to hydrogen assisted cracking. Duplex Stainless Steels (DSS) are considered as a proper class for components because of their many distinctive qualities. As this consideration depends strongly on the susceptibility level to Hydrogen Assisted Cracking (HAC), the DSS class has been broadly investigated under electrochemical charging conditions. In this work, the interplay between several factors controlling the level of HAC, was examined using light microscopy, high-pressure gaseous hydrogen pre-charging, Electron Backscatter Diffraction (EBSD), tensile testing, fractography and hydrogen concentration measurements using Carrier Gas Hot Extraction (CGHE). The effect of gaseous hydrogen on the mechanical properties with the role of hydrogen induced phase transformation have been investigated both in unused material and in high pressure pipeline section. In contrary to the common electrochemical charging described broadly in the literature, no significant martensitic phase transformation of the austenitic phase was observed. On the other hand, the influence of hydrogen on parameters such as elongation at fracture and reduction of area was noticeable. It is concluded based on the performance of DSS in gaseous hydrogen, that this material has a better potential for utilization in hydrogen applications. As for future experiments, the intention is to analyse the impact of high-pressure gaseous hydrogen on the welded components of this grade, and under mechanical load using the hollow specimen technique. T2 - 5th International Conference on Metals and Hydrogen CY - Ghent, Belgium DA - 14.10.2025 KW - High-Pressure Hydrogen KW - Pipelines KW - Duplex Stainless Steels KW - Hydrogen Assisted Cracking KW - Hollow Specimen Technique PY - 2025 SN - 978-9-08179-424-4 SP - 1 EP - 19 AN - OPUS4-64426 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Askar, Enis A1 - Schmidt, Martin A1 - El Harrab, Hayat A1 - Pekalski, Andrzej T1 - Ignition Indices of Hydrogen Mixtures under Electrolysis Process Conditions N2 - The formation of hydrogen-oxygen mixtures for example due to cross-over, malfunction or start-up and shut-down processes is a hazard very specific to given electrolysis processes that must be properly addressed. In this work the explosion limits of hydrogen-oxygen-mixtures at conditions up to 30 bar and 300 °C were determined experimentally. It was found that the existing experimental data can be interpolated with good accuracy using empirical approaches. Moreover, explosion limits at atmospheric conditions were also determined with reduced ignition energy, down to 1 mJ. Although in the literature it can be found that the ignition energy of flammable gases increases strongly when the concentration changes from stoichiometric to near the explosion limits, no significant influence on the mixture concentration was found within tested ignition energy range for H2/O2 mixtures. Finally, hot surface ignition for mixtures with 6 mol% hydrogen in oxygen, thus slightly above the explosion limit, were experimentally studied at different pressures up to 30 bara. Similarly, only slight difference from the ignition temperatures determined for stoichiometric mixtures were found. A 0D adiabatic, constant-volume reactor model was used to calculate the ignition temperatures. The model was tested for its prediction of ignition temperatures of hydrogen mixtures at different pressures. T2 - 11th International Conference on Hydrogen Safety (ICHS) 2025 CY - Seoul, South Korea DA - 22.09.2025 KW - Explosion limits KW - Ignition temperature KW - Ignition energy KW - Electrolyzer PY - 2025 SN - 979-12-243-0274-2 VL - 11 SP - 1259 EP - 1271 AN - OPUS4-64525 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gluth, Gregor ED - Wittke, W. T1 - Alkalisch aktivierter Beton (Geopolymer-Beton) N2 - Alkalisch aktivierte Bindemittel (AAB) sind Zemente, deren Erhärtung auf der alkalischen Anregung von reaktiven Aluminiumsilicaten beruht. AAB sind nach gegenwärtigem Stand die vielversprechendste Option, die mit der Herstellung und dem Einsatz von Zementen verbundenen CO2-Emissionen mittel- bis langfristig signifikant zu senken. Die Erhärtungsreaktionen und die Einflüsse auf die Mikrostruktur von AAB sind durch jahrzehntelange Forschung gut verstanden, und zahlreiche Beispiele belegen, dass AAB grundsätzlich als Betonbindemittel geeignet sind. Offene Fragen bestehen aber immer noch hinsichtlich der Dauerhaftigkeit von mit AAB hergestellten Betonen. Der vorliegende Beitrag gibt eine kurze Einführung in die Nomenklatur und die Geschichte von AAB. Die wichtigsten Reaktionen und Reaktionsprodukte, die zur Bildung der Mikrostruktur von AAB führen, werden beschrieben. Der Hauptteil des Beitrags diskutiert aktuelle Forschungsergebnisse und offene Fragen zur Dauerhaftigkeit von Betonen auf Basis von AAB. Wichtige Fortschritte auf diesem Gebiet konnten in den letzten Jahren insbesondere zum Einfluss von Sulfiden auf die Bewehrungskorrosion, zum Carbonatisierungswiderstand und zum Säurewiderstand erzielt werden. T2 - 10. Felsmechanik- und Tunnelbautag CY - Weinheim, Germany DA - 22.05.2025 KW - Alkali-activated materials KW - Carbonation KW - Reinforcement corrosion KW - MIC KW - Microbially induced corrosion PY - 2025 SN - 978-3-00-083562-9 SP - 73 EP - 84 PB - WBI GmbH CY - Weinheim AN - OPUS4-64266 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nicolicea, Alberto A1 - Pelkner, Matthias A1 - Melzer, Michael A1 - Oliveros-Mata, E. S. A1 - Zabila, Y. A1 - Makarov, D. T1 - Flexible AMR sensors for novel non-destructive testing capabilities N2 - Reshapeable magnetic field sensors fabricated on flexible substrates by thin-film deposi-tion or printing have recently emerged with promising applications in different field. In this study, flexible anisotropic magneto-resistive (AMR) sensors were used for the scanning of a curved and flat sample with reference defects, to prove the capability of this method for curved surface scanning, and to benchmark the performance when compared to a more standard method using rigid giant magneto-resistive (GMR) sensors. Defects with depths ranging from 110 μm up to 2240 μm were detected with a signal-to-noise ratio (SNR) of 2.7 up to 27.9 employing flexible AMR sensors. T2 - XMR-Symposium CY - Wetzlar, Germany DA - 12.03.2025 KW - non-destructive testing KW - Flexible sensor KW - Magnetoresistance PY - 2025 SP - 1 EP - 6 AN - OPUS4-65045 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meng, Xiangmeng A1 - Bachmann, Marcel A1 - Kising, Pascal A1 - Yang, Fan A1 - Rethmeier, Michael T1 - Prediction of weld pool and keyhole geometries in high-power laser beam welding through a physics-informed generative artificial intelligence approach N2 - The weld pool and keyhole geometries are critical characteristics in evaluating the stability of the high-power laser beam welding (LBW) process and determining the resultant weld quality. However, obtaining these data through experimental or numerical methods remains challenging due to the difficulties in experimental measurements and the high computational demands of numerical modelling. This paper presents a physics-informed generative approach for predicting weld pool and keyhole geometries in the LBW process. With the help of a well experimentally validated numerical model considering the underlying physics in the LBW, the geometries of the weld pool and keyhole under various welding conditions are calculated, serving as the dataset of the generative model. A Conditional Variational Autoencoder (CVAE) model is employed to generate realistic 2D weld pool and keyhole geometries from the welding parameters. We utilize a β-VAE model with the Evidence Lower Bound (ELBO) loss function and include Kullback-Leibler divergence annealing to better optimize model performance and stability during training. The generated results show a good agreement with the ground truth from the numerical simulation. The proposed approach exhibits the potential of physics-informed generative models for a rapid and accurate prediction of the weld pool geometries across a diverse range of process parameters, offering a computationally efficient alternative to full numerical simulations for process optimization and control in laser beam welding processes. T2 - International Congress of Applications of Lasers & Electro-Optics 2025 CY - Orlando, USA DA - 12.10.2025 KW - Laser beam welding KW - Generative artificial intelligence KW - Machine learning KW - numerical simulation PY - 2025 SP - 1 EP - 10 AN - OPUS4-65075 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mair, Georg W. A1 - Hajhariri, Aliasghar A1 - Sklorz, Christian A1 - Kriegsmann, Andreas A1 - Müller, Karsten T1 - A modular concept for protection against debris flight - Design, properties and usage N2 - With advances in technological development, stationary and mobile storage units for compressed hydrogen are becoming larger and larger. Their number is also increasing. At the same time, their design has evolved from steel and aluminium to pressure vessels made of composite materials. For safety reasons the design approval of those composite cylinders requires fire engulfment tests, which are mainly organised as open-air tests always needs dedicated protection measures. Under some conditions those protections measures even reduce the effort for organisational safety measures if e.g. the emission of splinters can get totally prevented. Another aspect is the improved reproducibility of fire tests by reducing the influence of wind. Between 2017 and 2019, BAM developed a stackable protective frame made of steel to safely capture splinters for the safe execution of high-energy impact tests. However, this frame was not flexible enough for the follow-up project, which led to a completely new protection concept for (potentially) destructive tests on gas-filled pressure vessels. This concept is based on very robust building blocks made from welded steel. Despite their considerable weight of around 500 kg p.p., they can be combined and stacked very easily like ‘Lego bricks’. The presentation will show the flexibility of the concept, some results of tests on the robustness against pressure waves and the effectiveness in wind attenuation. Finally, the interaction with a new, also modular burner concept for localised fires and full engulfment fires will be presented. T2 - 11th International conference on hydrogen safety (ICHS 2025) CY - Seoul, Republic of Korea DA - 22.09.2025 KW - Splinter protection KW - Pressure vessel testing KW - Fire engulfment KW - Destructive tests KW - Rupture KW - Gaseous tests KW - Pressure wave KW - Test equipment KW - Precaution measures PY - 2025 SN - 979-1-2243-0274-2 VL - 2025 SP - 1428 EP - 1439 AN - OPUS4-65100 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Channammagari, Harichandana A1 - Sahr, Rabea A1 - Trappe, Volker T1 - Experimentelle, Analytisch-Numerische Untersuchung des thermischen Ausdehnungsverhaltens von Faser-Kunststoff-Verbunden N2 - Im Rahmen des Forschungsvorhabens PROVING wurde eine Methode zur rechnerischen Bestimmung thermomechanischer Eigenspannungen in CFK entwickelt. Ziel ist die Berücksichtigung des thermischen Ausdehnungsverhaltens bei der Bestimmung des dreidimensionalen in-situ-Spannungszustands der Matrix für den strukturellen Nachweis. Die Eigenspannungen werden über mikromechanische Modellierung und FEM berechnet; die zugrunde liegenden Ausdehnungsfunktionen wurden experimentell validiert. N2 - As part of the PROVING research project, a method for calculating thermomechanical residual stresses in CFRP was developed. The aim is to take thermal expansion behavior into account when determining the three-dimensional in-situ stress state of the matrix for structural verification. The residual stresses are calculated using micromechanical modeling and FEM; the underlying expansion functions have been experimentally validated. T2 - 43. Vortrags- und Diskussionstagung Werkstoffprüfung 2025 CY - Dresden, Germany DA - 27.11.2025 KW - Thermische Eigenspannungen KW - Mikromechanik KW - Faser-Kunststoff-Verbunde KW - FEM PY - 2025 SN - 978-3-88355-454-9 VL - 2025 SP - 154 EP - 159 PB - DGM CY - Sankt Augustin AN - OPUS4-65112 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Huo, Wenjie A1 - Schmies, Lennart A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael A1 - Wolter, Katinka T1 - An illumination based backdoor attack against crack detection systems in laser beam welding N2 - Deep neural networks (DNNs) have been wildly used in engineering and have achieved state-of-the-art performance in prediction and measurement tasks. A solidification crack is a serious fault during laser beam welding and it has been proven to be successfully detected using DNNs. Recently, research on the security of DNNs is receiving increasing attention because it is necessary to explore the reliability of DNNs to avoid potential security risks. The backdoor attack is a serious threat, where attackers aim to inject an inconspicuous pattern referred to as trigger into a small portion of training data, resulting in incorrect predictions in the reference phase whenever the input contains the trigger. In this work, we first generate experimental data containing actual cracks in the welding laboratory for training a crack detection model. Then, targeting this scenario, we design a new type of backdoor attack to induce the model to predict the crack as a normal state. Considering the stealthiness of the attack, a common phenomenon during the welding process, illumination, is used as the backdoor trigger. Experimental results demonstrate that the proposed method can successfully attack the crack detection system and achieve over 90% attack success rate on the test set. T2 - 8th ML4CPS 2025 – Machine Learning for Cyber-Physical Systems CY - Berlin, Germany DA - 06.03,2025 KW - System security KW - Welding crack detection KW - Backdoor attack KW - Deep neural networks PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-651357 DO - https://doi.org/10.24405/20021 VL - 2025 SP - 12 EP - 21 PB - Universitätsbibliothek der HSU/UniBw H CY - Hamburg AN - OPUS4-65135 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -