TY - CONF A1 - Rhode, Michael T1 - Numerical simulation of weld heat input effect on microstructure and hydrogen diffusion in thick-walled S690 submerged arc welded joints N2 - High-strength, low-alloy (HLSA) steels such as S690 are an attractive option for heavy industries such as offshore wind turbines and peripheral equipment due to their combination of excellent mechanical properties and weldability. The construction of these thick-walled structures requires highly efficient welding processes such as submerged arc welding (SAW). However, SAW presents challenges related to delayed hydrogen assisted cold cracking (HACC). Despite its importance, the effect of different diffusion coefficients on the cold cracking susceptibility of different microstructures within SAW-welded S690 steels is not fully understood. For this reason, the present study focuses on comparing the cold cracking susceptibility of thermomechanically rolled (TM) or quenched and tempered (QL) variants of S690 steel. SAW was performed on specimens of both steel grades to produce weldments consisting of weld metal, heat-affected zone (HAZ), and base metal. Electrochemical hydrogen permeation tests (ISO 17081) were performed to determine the microstructure specific coefficients. Using the obtained coefficients, a numerical model was developed to identify the time- and microstructure-dependent local hydrogen diffusion and its influence on the distribution within the welds. The results showed that the TM grade exhibited slightly accelerated hydrogen diffusion compared to the QL grade, which is beneficial for hydrogen reduction and increases the HACC resistance. However, the further simulations with different ply sequences showed that the welding heat input (i.e. welding ply sequence) had a significantly higher effect on hydrogen accumulation. Specifically, increased welding heat input and increased thicknesses decrease hydrogen diffusivity. For this reason, microstructure-specific hydrogen diffusion played a minor role in thick-layer SAW joints compared to the need to control the welding parameters (layer sequence, individual layer thickness, welding heat input). T2 - FEMS Euromat 2025 - 18th European Congress and Exhibition on Advanced Materials and Processes CY - Granada, Spain DA - 15.09.2025 KW - Hydrogen assisted cracking KW - Welding KW - High strength steels KW - Numerical simulation KW - Electrochemical permeation PY - 2025 AN - OPUS4-64158 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Hydrogen trap characterization in 200 and 1,000 bar charged CoCrNi medium entropy alloy compared to steel AISI 316L N2 - Multiple principal element alloys (MPEAs) represent a new class of metallic materials. MPEAs, such as the CoCrNi medium entropy alloy (MEA), have attracted considerable research attention as potential materials to replace, for example, austenitic steels in high-pressure hydrogen environments. Due to the relatively new alloy concept, studies on the specific hydrogen diffusion and trapping behavior of high-pressure hydrogen-charged CoCrNi MEAs are rare so far. For this reason, a CoCrNi-MEA was investigated and compared to an austenitic stainless steel, AISI 316L. Both materials were subjected to high pressure hydrogen loading for two different pressures: 200 bar and 1,000 bar. After charging, thermal desorption analysis (TDA) was used with three heating rates from 0.125 K/s to 0.500 K/s to clarify the specific hydrogen desorption and trapping behavior. To the best of our knowledge, this study is the first to characterize hydrogen diffusion and trapping in 1,000 bar high-pressure charged CoCrNi. For this purpose, the underlying TDA spectra were analyzed in terms of peak deconvolution into a metallurgically justifiable number of defined peaks. The individual peak temperatures and activation energies “EA” were calculated. The following conclusions can be drawn from the results obtained: (1) Exposure to 200 bar or 1,000 bar leads to an increase in hydrogen absorption, regardless of the material investigated, expressed by a significantly increased desorption rate at 1,000 bar. However, the effusion peaks typically occur only at high temperatures. The (2) TDA showed that a four-peak deconvolution scenario was sufficient to describe the trapping behavior and the "EA" indicated the dominance of irreversible traps. In addition, the average trapping energy is higher than in the 316L. The (3) charge pressure related hydrogen solubility was in the order of: CoCrNi-MEA < 316L for both pressures and (4) charging at 1000 bar results in an average concentration of 49 wt.ppm (CoCrNi-MEA) and > 75 wt.ppm (316L). In summary, the CoCrNi-MEA was characterized by a reduced solubility, but very deep entrapment compared to the 316L. For this reason, further application potentials of the MEA may arise. T2 - FEMS Euromat 2025 - 18th European Congress and Exhibition on Advanced Materials and Processes CY - Granada, Spain DA - 15.09.2025 KW - Medium entropy alloy KW - Hydrogen KW - Trapping KW - Diffusion KW - High-pressure charging PY - 2025 AN - OPUS4-64160 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Effect of Ti and Nb on hydrogen trapping in welded S690 HSLA steel and effect on delayed cold cracking N2 - Fine-grain, high-strength, low-alloy (HSLA) structural steels with yield strengths > 600 MPa are now the state of the art in construction applications such as mobile cranes and civil engineering. HSLA grades derive their strength from a combination of specific heat treatment and the underlying chemical composition. In this context, Ti or Nb are essential to obtain a fine-grained microstructure as well as the necessary carbides or nitrides for precipitation strengthening. In this context, the specific effect of Ti or Nb-rich compounds on hydrogen trapping and diffusion is well known for special laboratory cast alloys, but unknown for realistic steel compositions. For this reason, a series of S690Q-based alloys were synthesized, close to a real steel composition, but with well controlled Ti or Nb additions in different amounts. Specimens were obtained from these alloys by electrochemical discharge machining (EDM). The specimens were tested using the well-established electrochemical permeation technique. From the experimental results, the hydrogen diffusion coefficients and the analytical subsurface hydrogen concentration were calculated. In addition, the hydrogen trapping behavior at elevated temperatures was interpreted by thermal desorption analysis (TDA) using different heating rates of hydrogen charged samples. The results showed that in contrast to metallurgically "pure" laboratory cast alloys, realistic chemical compositions were similar in their hydrogen trapping behavior, despite some small differences. All investigated steel grades exhibited shallow and reversible hydrogen trapping, regardless of their chemical composition. Of course, the experiments only allowed the calculation of effective diffusion coefficients and trapping energies, which represent an average of the entire microstructure. Nevertheless, HSLA steels are typically joined by arc welding, which includes the risk of delayed hydrogen assisted cracking. From the point of view of welding practice, however, a more or less identical hydrogen diffusion behavior means that no special "metallurgically specific", justifiable measures need to be considered, despite the well-established processes such as "soaking" or dehydrogenation heat treatment. Of course, a closer look at the heat-affected zone (HAZ) or the weld metal of the specific welds is necessary. However, especially in the case of thick-walled welds, it is assumed that the weld metal and HAZ are similar to the base material due to the multi-layer welding, which results in multiple annealing cycles of the weld metal and HAZ. T2 - FEMS Euromat 2025 - 18th European Congress and Exhibition on Advanced Materials and Processes CY - Granada, Spain DA - 15.09.2025 KW - Hydrogen assisted cracking KW - HSLA KW - Diffusion KW - Electrochemical permeation PY - 2025 AN - OPUS4-64156 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael T1 - Component test for the assessment of in-service welding on/onto pressurized hydrogen pipelines N2 - Hydrogen is the energy carrier of tomorrow and requires a reliable large-scale transport infrastructure. In addition to new pipelines, the conversion of existing natural gas (NG) pipeline grids is an essential part. The transport of hydrogen is fundamentally different from that of NG, as hydrogen can be absorbed into the pipeline material. Given the effects of hydrogen embrittlement, the material compatibility (low alloy steels in a wide range of strengths and thicknesses) must be investigated. However, pipelines e.g. require maintenance or the need for installation of additional outlets with the necessity of welding on/onto the pipelines while they are still in service, i.e. with gas flow under high pressure, such as the well-known "hot tapping". This in-service welding poses challenges for hydrogen operations. The challenge can be roughly divided into the possible austenitization of the inner pipe material exposed to hydrogen, the welding itself, which causes an increased temperature range. Both lead to a significant increase in hydrogen solubility and diffusivity compared to room temperature. In addition, possible surface reactions of the present iron oxides (e.g. magnetite or hematite) with the hot hydrogen should be considered. In this context, the knowledge of hydrogen pipelines is scarce due to the lack of operational experience. Fundamental experimental investigations are required to investigate the transferability from NG to hydrogen pipeline grids. For this reason, the present study presents a specially designed mock-up / demonstrator concept for the realistic assessment of the welding process conditions. The mock-up was designed to allow in-situ temperature measurement during the welding process as well as ex-post sample extraction for quantification of the absorbed hydrogen concentration. For safety reasons, the required volume of pressurized hydrogen was limited by inserting a solid cylinder to ensure a 1 cm thick layer of hydrogen gas. Welding experiments on the DN60 and DN200 pressurized mock-ups showed the possibility of safe welding on or onto pressurized hydrogen pipelines. Indeed, the austenitizing temperature was reached on the inner surface of the pipeline, especially on thinner-walled pipelines, using current welding parameter recommendations. This corresponded to an increased hydrogen uptake in the welded area of several ppm. From this point of view, the suggested component concept is a viable strategy for the screening of several materials and welding parameter combinations under realistic operational conditions. T2 - FEMS Euromat 2025 - 18th European Congress and Exhibition on Advanced Materials and Processes CY - Granada, Spain DA - 15.09.2025 KW - In-service welding KW - Pipeline KW - Hydrogen KW - Component test PY - 2025 AN - OPUS4-64159 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Seifert, Lando A1 - Eggert, Lara T1 - Weathering Campaigns in the North Sea for an Offshore Power-to-X Project N2 - The poster contributes to the assessment of corrosivity in offshore atmospheric exposure environments according to DIN EN ISO 9224 for unalloyed steel, zinc, copper and aluminium. Studies on corrosivity from an offshore wind turbine and a distribution platform in the North Sea are presented. The results show that the corrosivity of unalloyed steel is mostly dependent on the altitude of exposure and whether it is inside or outside. T2 - Conference EUROCORR 2025 CY - Stavanger, Norway DA - 07.09.2025 KW - Weathnering Campaigns KW - North Sea KW - Corrosivity KW - Corrosion KW - Atmospheric Corrosion KW - Mass Loss KW - Corrosion Rate KW - Offshore Wind Turbine PY - 2025 AN - OPUS4-64086 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Chaudhuri, Somsubhro T1 - Infrared thermography as an inspection tool for wind turbine rotor blades N2 - This presentation explores the use of infrared thermography as an inspection tool for wind turbine rotor blades. It highlights the implementation of ground-based thermographic techniques, demonstrates what can be achieved through such inspections, and presents a case study conducted in partnership with Statkraft. Particular attention is given to the discussion of thermal contrast and how it can be obtained for effective defect detection. To assess the potential and limitations of thermography, results from controlled climate chamber experiments and complementary simulations are also presented. T2 - IQPC Wind Week 2025 CY - Bremen, Germany DA - 26.08.2025 KW - Thermography KW - Thermografie KW - Wind turbine rotor blades KW - Windenergie anlage rotorblätte KW - Damage detection PY - 2025 AN - OPUS4-64056 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Graeber, Gustav T1 - Paste-like interlayers in alkali-metal battery anodes N2 - Giving an introduction to high-temperature batteries with molten alkali-metal anodes and solid electroyltes. Presenting the research on alkali-metal tensiometry and the study about wetting interactions between liquid alkali-metal alloys and porous carbon hosts. T2 - AG Christina Roth Seminar CY - Bayreuth, Germany DA - 16.07.2025 KW - Battery PY - 2025 AN - OPUS4-64069 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Graeber, Gustav T1 - Graeber Lab for Energy Research at Tag der Chemie in Adlershof N2 - Highlighting recent progress in the Graeber Lab for Energy Research in the areas of alkali-metal tensiometry, alkali-metal anodes in contact with solid electrolytes, sulfur cathodes and solid electrolyte synthesis. T2 - Tag der Chemie in Adlershof 2025 CY - Berlin, Germany DA - 03.07.2025 KW - Batterie PY - 2025 AN - OPUS4-64068 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Graeber, Gustav T1 - Paste-like alkali-metal anodes in contact with solid electroytes N2 - Explaining the motivation of the BMFTR ANaBatt project. Presenting recent advances in alkali metal tensiometry and characterization of alkali-metal wetting in porous carbon materials via X-ray computed tomography. T2 - Sodium Battery Symposium 6 CY - Dresden, Germany DA - 03.09.2025 KW - Battery PY - 2025 AN - OPUS4-64070 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Holt, Erika A1 - Oksa, Maria A1 - Banford, Anthony A1 - Carbol, Paul A1 - Abdelouas, Abdesselam A1 - Giboire, Isabelle A1 - Mennecart, Thierry A1 - Niederleithinger, Ernst T1 - Predisposal Radioactive Waste Management (PREDIS) Project Final Achievements and Impacts Overview N2 - The PREDIS project on Predisposal of Radioactive Waste has succeeded in developing and implementing new methods, processes and technologies for treatment of challenging low-level waste (LLW) and intermediate level waste (ILW) streams. Over the 4-year duration, this Euratom project of 47 partners from 17 Member States has worked in close collaboration with 25 End User industrial members to advance the technologies associated with predisposal issues. This has included characterisation followed by treatment, conditioning and processing of metallics, liquid organic and solid organic wastes as well as with digitalization technologies for assessing performance of concrete waste packages and pre-disposal storage. Long-term modelling and performance testing have been done to verify the safety and effectiveness of the new or enhanced solutions. Value Assessments were done for some of the new solutions to ensure implementors would have sufficient tools for making choices about the potential implementation. This included life-cycle assessment of quantitative sustainability indicators and life cycle-costing for economic indicators. This project addressed new guidance on Waste Acceptance Criteria and contributed with a revised Strategic Research Agenda to guide future predisposal activities, complimentary to the holistic waste management programme. Knowledge Management actions were also an integral part of the whole project to foster competence development and capturing knowledge. Actions included training, mobility, and guidance especially through online forums such as webinars and digital training. This paper provides a snapshot of some of the key outcomes and impacts from the project, from technical as well as strategic and knowledge perspectives. KW - Nuclear waste KW - Pre-disposal KW - Intermediate storage KW - Treatment KW - Monitoring PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-638480 DO - https://doi.org/10.1051/epjn/2025028 SN - 2491-9292 VL - 11 SP - 1 EP - 7 PB - EDP Sciences AN - OPUS4-63848 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kemmler, Samuel A1 - Rettinger, Christoph A1 - Rüde, Ulrich A1 - Cuéllar, Pablo A1 - Köstler, Harald T1 - Efficiency and scalability of fully-resolved fluid-particle simulations on heterogeneous CPU-GPU architectures N2 - Current supercomputers often have a heterogeneous architecture using both conventional Central Processing Units (CPUs) and Graphics Processing Units (GPUs). At the same time, numerical simulation tasks frequently involve multiphysics scenarios whose components run on different hardware due to multiple reasons, e.g., architectural requirements, pragmatism, etc. This leads naturally to a software design where different simulation modules are mapped to different subsystems of the heterogeneous architecture. We present a detailed performance analysis for such a hybrid four-way coupled simulation of a fully resolved particle-laden flow. The Eulerian representation of the flow utilizes GPUs, while the Lagrangian model for the particles runs on conventional CPUs. Two characteristic model situations involving dense and dilute particle systems are used as benchmark scenarios. First, a roofline model is employed to predict the node level performance and to show that the lattice-Boltzmann-based Eulerian fluid simulation reaches very good performance on a single GPU. Furthermore, the GPU-GPU communication for a large-scale Eulerian flow simulation results in only moderate slowdowns. This is due to the efficiency of the CUDA-aware MPI communication, combined with the use of communication hiding techniques. On 1024 A100 GPUs, an overall parallel efficiency of up to 71% is achieved. While the flow simulation has good performance characteristics, the integration of the stiff Lagrangian particle system requires frequent CPU-CPU communications that can become a bottleneck, especially when simulating the dense particle system. Additionally, special attention is paid to the CPU-GPU communication overhead since this is essential for coupling the particles to the flow simulation. However, thanks to our problem-aware co-partitioning, the CPU-GPU communication overhead is found to be negligible. As a lesson learned from this development, four criteria are postulated that a hybrid implementation must meet for the efficient use of heterogeneous supercomputers. KW - Discrete element method KW - Hybrid implementation KW - High-performance computing KW - Particulate flow KW - Lattice Boltzmann method PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-623958 DO - https://doi.org/10.1177/10943420241313385 SN - 1741-2846 SP - 1 EP - 19 PB - SAGE Publications AN - OPUS4-62395 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zinas, Orestis A1 - Papaioannou, Iason A1 - Schneider, Ronald A1 - Cuéllar, Pablo T1 - Multivariate Gaussian Process Regression for 3D site characterization from CPT and categorical borehole data N2 - Accurate prediction of subsurface stratigraphy and geotechnical properties, along with quantification of associated uncertainties, is essential for improving the design and assessment of geotechnical structures. Several studies have utilized indirect data from Cone Penetration Tests (CPTs) and employed statistical and Machine Learning methods to quantify the geological and geotechnical uncertainty. Incorporating direct borehole data can reduce uncertainties. This study proposes a computationally efficient multivariate Gaussian Process model that utilizes site-specific data and: (i) jointly models multiple categorical (USCS labels) and continuous CPT variables, (ii) learns a non-separable covariance structure leveraging the Linear Model of Coregionalization, and (iii) predicts a USCS based stratigraphy and CPT parameters at any location within the 3D domain. The results demonstrate that integrating geotechnical and geological data into a unified model yields more reliable predictions of subsurface stratification, enabling the parallel interpretation of both USCS classification and CPT profiles. Importantly, the model demonstrates its potential to integrate multiple variables from different sources and data types, contributing to the advancement of methodologies for the joint modeling of geotechnical, geological, and geophysical data. KW - Geotechnical site-characterization KW - Cone Penetration Tests KW - Stratigraphy prediction KW - Multivariate Gaussian process KW - Variational inference KW - Linear Model of Coregionalization PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-629456 DO - https://doi.org/10.1016/j.enggeo.2025.108052 SN - 1872-6917 VL - 352 SP - 1 EP - 19 PB - Elsevier B.V. AN - OPUS4-62945 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wosniok, Aleksander T1 - Ortsverteilte faseroptische Sensorik zur Zustandsüberwachung von H2-Druckbehältern für den Automobileinsatz N2 - Ergebnisse der Forschungsarbeit zur Zustandsüberwachung von Druckbehältern des Typs IV unter Verwendung ortsverteilter faseroptischer Sensoren. Die Sensorfasern werden in die Kompositstruktur integriert, indem sie während des Herstellungsprozesses der Druckbehälter in die Kreuz- und die Umfangslage um den Kunststoff-Liner gewickelt werden. Der anschließende Einsatz der optischen Rückstreureflektometrie (OBR) ermöglicht eine präzise Detektion und Lokalisierung von Strukturschäden während der gesamten Lebensdauer. Die vorgestellte Arbeit steht im Kontext des europäischen Horizon 2020-Forschungsprojekts SH2APED, das sich mit der Entwicklung eines innovativen Wasserstoffspeichersystems für den Automobileinsatz befasste. T2 - DGZfP-Jahrestagung CY - Berlin, Germany DA - 26.05.2025 KW - Ortsverteilter faseroptischer Sensor KW - Optische Rückstreureflektometrie KW - Berstprüfung KW - Lastwechselprüfung KW - Druckbehälter PY - 2025 AN - OPUS4-63269 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bernardy, Christopher A1 - Habib, Abdel Karim A1 - Kluge, Martin A1 - Schalau, Bernd A1 - Kant, Hanjo A1 - Schulze, Marcel A1 - Orchini, Alessandro T1 - Large-scale investigations of the thermal radiation of hydrogen jet flames N2 - For industrial applications dealing with hydrogen, the definition of safety distances and the assessment of possible hazards emanating from releases is mandatory. Since hydrogen is usually stored and transported under pressure, one scenario to be considered is the momentum driven release of hydrogen from a leakage with subsequent ignition. In this scenario, the emitted heat radiation from the resulting jet flame to the surroundings has to be determined to define adequate safety distances. For hydrocarbon flames, different jet flame models are available to assess the hazards resulting from an ignited jet release. Since hydrogen flames differ from hydrocarbon flames in their combustion behavior, it has to be checked if these models are also applicable for hydrogen. To evaluate the accuracy of these models for hydrogen jet flames, tests with a horizontal outlet at large-scale are carried out at the BAM Test Site for Technical Safety (BAM-TTS). Herein, the flame geometry and the heat radiation at defined locations in the surroundings are recorded for varying release parameters such as release pressure (currently up to max. 250 bar), mass flow (up to max. 0.175 kg/s) at an outlet diameter of 30 mm (with an upstream nozzle of 7.7 mm). The challenge here is the characterization of the flame geometry in an open environment and its impact on the thermal radiation. Existing heat radiation data from the literature are mostly based on unsteady outflow conditions. For a better comparability with the steady state jet flame models, the experiments presented here are focused on ensuring a constant mass flow over the release duration (currently 120 s) to obtain a stationary jet flame. In addition, stationary outflow tests with hydrocarbons (methane) were also carried out, which are intended to serve as reference tests for checking flame models based on hydrocarbon data. The comparison of the flame geometry shows that hydrogen jet flames with the same outlet mass flow have a greater flame length (average deviation of 15 %) but a smaller flame diameter than methane jet flames (average deviation of 17 %). Conclusions regarding thermal radiation show that the proportion of total combustion energy emitted as thermal radiation is lower for hydrogen (x_rad= 0.04–0.09) than for methane (x_rad = 0.06–0.1). A comparison of the surface emissive power (SEP) of the jet flame shows a SEP range of 7 kW/m2-15 kW/m2 for hydrogen and 3 kW/m2 - 9,5 kW/m2 for methane. KW - Hydrogen KW - Release KW - Thermal radiation KW - Jet flame KW - Radiant heat fraction PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-622891 DO - https://doi.org/10.1016/j.jlp.2024.105491 SN - 1873-3352 VL - 94 SP - 1 EP - 6 PB - Elsevier B.V. AN - OPUS4-62289 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Balscheit, Hagen T1 - Evaluation of pile tip buckling based on large scale tests N2 - Der Vortrag zum zugehörigen Konferenzbeitrag beschreibt eine groß angelegte Feldtestkampagne mit 16 Rammversuchen, um das Risiko des plastischen Versagens der Pfahlspitzen besser zu verstehen Ein numerisches Modell mit transientem Bodenkontakt zeigt eine gute Übereinstimmung mit den Testergebnissen. Parametervariationen verdeutlichen, wie empfindlich die Pfahlreaktion auf Imperfektionen und Randbedingungen ist. T2 - 5th International Symposium on Frontiers in Offshore Geotechnics (ISFOG) CY - Nantes, France DA - 09.06.2025 KW - Pile Tip Buckling KW - Monopile KW - Offshore Windenergy KW - Driving Refusal KW - Large Scale Test PY - 2025 AN - OPUS4-63391 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhang, Wuyi A1 - Mehmood, Asad A1 - Ali, Ghulam A1 - Liu, Hui A1 - Chai, Liyuan A1 - Wu, Jun A1 - Liu, Min T1 - Nickel Nanocluster-Stabilized Unsaturated Ni–N3 Atomic Sites for Efficient CO2-to-CO Electrolysis at Industrial-Level Current N2 - Unsaturated Ni single-atom catalysts (SACs), Ni-Nx (x=1,2,3), have been investigated to break the conventional Ni-N4 structural limitation and provide more unoccupied 3d orbitals for CO2 reduction reaction (CO2RR) intermediates adsorption, but their intrinsically low structural stability has seriously hindered their applications. Here, we developed a strategy by integrating Ni nanoclusters to stabilize unsaturated Ni-N3 atomic sites for efficient CO2 electroreduction to CO at industrial-level current. Density Functional Theory (DFT) calculations revealed that the incorporation of Ni nanocluster effectively stabilizes the unsaturated Ni-N3 atomic sites and modulates their electronic structure to enhance the adsorption of the key intermediate *COOH during CO2RR. Guided by these insights, we prepared an optimal composite catalyst, Ni6@Ni-N3, which features a Ni6N6 nanocluster surrounded by six Ni-N3 single atoms sites, through low-temperature pyrolysis. The morphology and coordinative structure of Ni6@Ni-N3 were confirmed by an aberration-corrected transmission electron microscope (AC-TEM) and X-ray absorption spectroscopy (XAS). As a result, Ni6@Ni-N3 demonstrated a remarkably high CO Faradaic efficiency (FECO) of 99.7 % and a turnover frequency (TOF) of 83984.2 h−1 at 500 mA cm−2 under −1.15 VRHE, much better than those of Ni-N4 with a lower FECO of 86 % at 100 mA cm−2 and a TOF of 39309.9 h−1under identical potential. XAS analyses of Ni6@Ni-N3 before and after long-term CO2RR testing confirmed the excellent stability of its coordinative environment. This work highlights a generalizable approach for stabilizing unsaturated single-atom catalysts, paving the way for their application in high-performance CO2RR. KW - Electrochemical CO2 conversion KW - Single atom catalysts KW - CO2 electrolysis PY - 2025 DO - https://doi.org/10.1002/anie.202424552 SN - 1521-3773 VL - 64 IS - 13 SP - 1 EP - 10 PB - Wiley-VCH CY - Weinheim AN - OPUS4-62926 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Koch, Claudia T1 - Digitale QI: Inspektion von Rotorblättern von Windenergieanlagen N2 - Der Vortrag erklärt, was eine digitale Qualitätsinfrastruktur umfasst und stellt Arbeiten vor, die die Inspektion von Rotorblättern effizienter machen und bessere Einblicke in den Zustand geben soll. Grundlage dafür sind thermografische Aufnahmen und eine KI-gestützte Auswertung. Auch die Rolle von Datenräumen und Digitalem Produktpass wird behandelt. T2 - Plattform Industrie 4.0 Projektgruppenmeeting Collaborative Condition Monitoring CY - Online meeting DA - 17.06.2025 KW - Qualitätsinfrastruktur KW - Qualitätssicherung KW - Digitalisierung KW - Inspektion KW - Thermografie KW - Künstliche Intelligenz PY - 2025 AN - OPUS4-63452 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Graeber, Gustav T1 - Batterieforschung an der Humboldt-Universität zu Berlin - Selbstvorstellung beim KLiB N2 - Selbstvorstellung der Batterieforschungsaktivitäten der HU Berlin in Kooperation mit lokalen Partnern wie der BAM im Rahmen eines Netzwerktreffens. Fokus auf die Forschung in der Arbeitsgruppe Graeber zu Festkörperbatterien und der Arbeitsgruppe Adelhelm zu Natrium-Ionen-Batterien. T2 - KLiB Netzwerktreffen CY - Frankfurt, Germany DA - 26.03.2025 KW - Batterie PY - 2025 AN - OPUS4-63350 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Graeber, Gustav T1 - Graeber Lab for Energy Research - Overview N2 - Vorstellung der Forschungsaktivitäten der AG Graeber an der HU Berlin und an der BAM. Diese beinhalten die Erforschung grundlegender Benetzungsphänomene von Alkalimetallen, deren Anwendung in Festkörperbatterien mit pastenartigen Alkalimetallanoden, die Erforschung von Schwefelkathoden, die Synthese von Natrium-leitenden Festelektrolyten sowie die Entwicklung von Hydrogel-basierten Batterien. T2 - BMBF BattFutur NanoMatFutur Netzwerktreffen 2025 CY - Berlin, Germany DA - 24.02.2025 KW - Batterie PY - 2025 AN - OPUS4-63361 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Qi, Naiyu A1 - Somaskandan, Rachana A1 - Graeber, Gustav T1 - High-Precision Surface Tension Measurements of Sodium, Potassium, and Their Alloys via Du Noüy Ring Tensiometry N2 - The development of post-lithium-ion batteries has sparked significant interest in alkali-metal anodes, particularly sodium (Na), potassium (K), and sodium−potassium (Na−K) alloys. Na−K alloys are promising for partially liquid anodes due to their unique low melting points. A critical factor influencing Na−K-based anode performance is wetting behavior, which governs electrical conductivity, mechanical contact, and long-term stability. At the heart of wetting lies surface tension, a fundamental property of solid−liquid− gas interactions. However, the surface tension of alkali metals and their alloys, particularly Na−K systems, remains poorly understood due to experimental and theoretical challenges. This study bridged these gaps by employing Du Noüy ring tensiometry for the first time in alkali-metal systems to measure the surface tension of Na, K, and Na−K alloys across temperatures from ambient to 180 °C. A key innovation in this work is the development of the push-in Du Noüy method, which provided significantly higher precision and reliability compared to the traditional pull-out technique, without requiring a correction factor. The measured surface tension decreased with increasing temperature for the studied Na−K alloys. For instance, for a eutectic Na−K mixture, the surface tension decreases from 121.7 mN m−1 to 112.2 mN m−1 when increasing the temperature from ambient to 180 °C. Additionally, this study presented the first use of Gibbs free energy minimization to model the surface tension of the Na−K system. The robust method significantly enhanced the predictive accuracy compared to the previous simplified model, reducing deviations from 25% to 2%. Our findings reveal that surface tension increases with sodium mole fraction in the bulk phase, yet the surface monolayer remains potassium-rich, indicating non-ideal surface behavior. This study deepens the understanding of alkali-metal wetting behavior, providing valuable insights for designing optimized interfaces in next-generation semi-solid alkali-metal batteries. KW - Sodium−potassium alloy KW - Liquid-metal anodes KW - Alkali metal KW - Batteries KW - Surface tension PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-630102 DO - https://doi.org/10.1021/acsami.5c02183 SN - 1944-8252 VL - 17 IS - 17 SP - 25985 EP - 25995 PB - American Chemical Society (ACS) CY - Washington, DC AN - OPUS4-63010 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zinas, Orestis A1 - Papaioannou, Iason A1 - Schneider, Ronald A1 - Cuéllar, Pablo A1 - Baeßler, Matthias T1 - 3D spatial modelling of CPT data for probabilistic preliminary assessment of potential pile tip damage upon collision with boulders N2 - Tip damage of monopiles from boulder collisions during installation has emerged as a critical design issue, primarily due to the combination of the widespread use of large-diameter piles and the complexity of the ground conditions at the available sites. Recently, a framework relating potential pile tip damage to cone tip resistance from Cone Penetration Tests (CPTs) has been proposed in the literature. Gaussian processes are powerful stochastic models that enable probabilistic spatial interpolation of soil data at any location within a site. On this basis, this study utilizes sparse CPT data from a site in the North Sea, to first develop an efficient Gaussian process regression model, which is used to derive a three-dimensional (3D) probabilistic predictive map of the cone tip resistance. Assuming deterministic loading conditions and a factual collision with a boulder of pre-defined properties, the cone tip resistance predictive model is subsequently used for a probabilistic preliminary assessment of potential pile tip damage. Results of the analysis are realistic 3D probability maps of potential damage that aim to support engineering judgment and contribute towards cost-effective site investigation planning and offshore wind farm design. T2 - 5th International Symposium on Frontiers in Offshore Geotechnics (ISFOG 2025) CY - Nantes, France DA - 09.06.2025 KW - CPT data KW - Gaussian process regression KW - Boulder impact KW - Preliminary pile tip damage assessment PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-634417 SN - 978-2-85782-758-0 DO - https://doi.org/10.53243/ISFOG2025-323 SP - 505 EP - 510 PB - International Society for Soil Mechanics and Geotechnical Engineering CY - London AN - OPUS4-63441 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Baeßler, Matthias A1 - Balscheit, Hagen A1 - Geißler, Peter A1 - Schepers, Winfried A1 - Cuèllar, Pablo T1 - Evaluation of pile tip buckling based on large scale tests N2 - Der Beitrag beschreibt eine groß angelegte Versuchskampagne mit Pfahlrammungen, um das Risiko des plastischen Versagens der Pfahlspitze besser zu verstehen und numerische Modelle zu validieren. Ein numerisches Modell mit transientem Bodenkontakt zeigt eine gute Übereinstimmung mit den Testergebnissen. Parametervariationen verdeutlichen, wie empfindlich die Pfahlreaktion auf Imperfektionen und Randbedingungen ist. T2 - 5TH INTERNATIONAL SYMPOSIUM ON FRONTIERS IN OFFSHORE GEOTECHNICS CY - Nantes, France DA - 09.06.2025 KW - Pile Tip Buckling KW - Monopile KW - Offshore Windenergy KW - Driving Refusal KW - Large Scale Test PY - 2025 SN - 978-2-85782-758-0 DO - https://doi.org/10.53243/ISFOG2025-476 SP - 1218 EP - 1223 PB - International Society for Soil Mechanics and Geotechnical Engineering (ISSMGE) CY - Nantes AN - OPUS4-63387 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zinas, Orestis T1 - 3D spatial modelling of CPT data for probabilistic preliminary assessment of potential pile tip damage upon collision with boulders N2 - Tip damage of monopiles from boulder collisions during installation has emerged as a critical design issue, primarily due to the combination of the widespread use of large-diameter piles and the complexity of the ground conditions at the available sites. Recently, a framework relating potential pile tip damage to cone tip resistance from Cone Penetration Tests (CPTs) has been proposed in the literature. Gaussian processes are powerful stochastic models that enable probabilistic spatial interpolation of soil data at any location within a site. On this basis, this study utilizes sparse CPT data from a site in the North Sea, to first develop an efficient Gaussian process regression model, which is used to derive a three-dimensional (3D) probabilistic predictive map of the cone tip resistance. Assuming deterministic loading conditions and a factual collision with a boulder of pre-defined properties, the cone tip resistance predictive model is subsequently used for a probabilistic preliminary assessment of potential pile tip damage. Results of the analysis are realistic 3D probability maps of potential damage that aim to support engineering judgment and contribute towards cost-effective site investigation planning and offshore wind farm design. T2 - 5th International Symposium on Frontiers in Offshore Geotechnics (ISFOG) CY - Nantes, France DA - 09.06.2025 KW - CPT data KW - Gaussian process regression KW - Boulder impact KW - Preliminary pile tip damage assessment PY - 2025 AN - OPUS4-63444 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Richter, Matthias T1 - Primary References for the Determination of Sulphur Impurities in Hydrogen N2 - Fuel cell electric vehicles are expanding quickly from light-duty to heavy-duty applications, such as buses or trucks. Hydrogen fuel quality needs to comply with ISO 14687:2025 to avoid any harmful impact on the vehicles. Total sulphur is one of the most impactful contaminants to a fuel cell system and has a threshold of 4 nmol/mol. In the European Partnership for Metrology (EPM) project Met4H2, BAM together with VSL, the National Metrology Institute of the Netherlands, developed novel gaseous primary reference materials (PRM) to improve the accuracy of the analysis of 7 sulphur compounds (hydrogen sulphide, carbonyl sulphide, methyl mercaptan, ethyl mercaptan, dimethyl sulphide, diethyl sulphide, and tetrahydrothiophene) for the quality control of hydrogen as fuel gas at this challenging amount fraction. These PRM were cross-validated using thermal desorption gas chromatography with a sulphur chemiluminescence detector (TD-GC/SCD). The results are presented and limits discussed. T2 - Joint workshop EMN for Energy Gases CY - Delft, Netherlands DA - 26.03.2025 KW - Sulphur impurities KW - Hydrogen KW - GC/SCD KW - Reference gas standards PY - 2025 AN - OPUS4-62818 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fey, Gero T1 - Thermophysically Simulated Weld HAZ and CCT Diagram of� High Strength Low Alloy Pipeline Steel N2 - Kurzvorstellung der laufenden Projekte "Wasserstoffabhängige mechanische Eigenschaften der Schweißnahtgefüge niedriglegierter Stähle für Ferngasleitungen" und "Praktikable Prüfung geschweißter Ferngasleitungen aus niedrig-legierten Stählen für den sicheren Transport von Wasserstoff" mit kurzem Ergebnisstand und zukünftiger Versuchsplanung/Outlook T2 - Sitzung des NA 092-00-05 GA "Gemeinschaftsarbeitsausschuss NAS/NMP: Zerstörende Prüfung von Schweißverbindungen (DVS AG Q 4/Q 4.1)" CY - Online meeting DA - 20.03.2025 KW - ZTU-Diagramm KW - CCT KW - WEZ KW - Dilatometry KW - Pipeline Steel PY - 2025 AN - OPUS4-63107 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Willeke, Maraike A1 - Giese, Marcel A1 - Lorenz, Swenja A1 - Treutler, Kai A1 - Schröpfer, Dirk A1 - Wesling, Volker A1 - Kannengießer, Thomas T1 - Effect of alloy modification on the wear protection coatings made of Ni- and Co-based materials and surface machinability via ultrasonic milling process N2 - AbstractWear-resistant coatings are required for highly efficient and economical steel components in equipment, process, and power plant engineering to withstand high corrosive, tribological, thermal, and mechanical stresses. Co-alloys are used as wear-resistant coatings for steel components, tailored to the specific application. The substitutability of Co alloys with Ni-based wear protection systems, in addition to price and supply uncertainties, is facilitated by the combination of innovative welding and machining processes such as ultrasonic-assisted milling. The aim of the study is to improve the machinability of two different hard-facing alloys while maintaining the same wear protection potential. Therefore, the wear-resistant alloys NiMoCrSi (Colmonoy C56) and CoMnCrSi (Tribaloy T400) were modified by the alloying additions Nb, Hf, and Ti and then applied to a carbon-manganese steel S355 using the plasma transfer arc (PTA) welding process. The influence of the alloying additions on the microstructure as KW - Wear resistance KW - Co-based alloy KW - Ni-based alloy KW - PTA welding process KW - Ultrasonic assisted milling process PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-623931 DO - https://doi.org/10.1007/s00170-024-14955-0 SN - 0268-3768 SP - 1 EP - 17 PB - Springer Science and Business Media LLC AN - OPUS4-62393 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Liepold, Philipp A1 - Kromm, Arne A1 - Kannengießer, Thomas T1 - Transvarestraint testing of high-strength steel filler metal N2 - High-strength steel welds are typically not known to be susceptible to Solidification Cracking (SC). However, modern light-weight constructions may force welding in highly restrained conditions, which are known to increase the probability of Solidification Crack (SC) emergence. In this article, the Modified Varestraint-Transvarestraint (MVT) test was used to evaluate the hot cracking susceptibility of welds made from high-strength, low-alloyed filler material. The materials tested include solid wires and a metal-cored wire. All wires are typically used in the Gas Metal Arc Welding (GMAW) process. Susceptibility to SC was measured over a wide range of welding parameters and bending speeds. Results show little affinity of the tested materials to SC. However, crack length increases in most cases with arc energy ( U ∙ I∕welding speed ) and welding speed. The length of the longest crack in one test specimen follows a similar trend until high welding speeds, where stagnation of crack length with changing arc energy was observed. KW - MVT KW - Varestraint KW - Transvarestraint KW - Solidification cracking KW - High-strength steel PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-630084 DO - https://doi.org/10.1007/s40194-025-02042-1 SN - 1878-6669 VL - 2025 SP - 1 EP - 12 PB - Springer CY - Berlin ; Heidelberg AN - OPUS4-63008 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - THES A1 - Quackatz, Lukas T1 - In situ Untersuchung der Phasenverteilung und der Schmelzbaderstarrung von Duplexstählen mittels laserinduzierter Plasmaspektroskopie (LIBS) N2 - Nichtrostende Duplexstähle (DSS) werden in allen Branchen eingesetzt, bei denen eine hohe Festigkeit in Verbindung mit einer hohen Korrosionsbeständigkeit in aggressiven Medien ge-fordert wird. Beispiele hierfür sind Kraftwerkskomponenten und maritime Strukturen. DSS ha-ben ein ausgewogenes Phasenverhältnis von Ferrit (α) und Austenit (γ). Im Gegensatz zu einphasigen nichtrostenden Stählen vereinen DSS die Vorteile dieser beiden Phasen und kön-nen daher viele Anforderungen der Industrie erfüllen, wie z. B. Gewichtseinsparung oder hohe mechanische Festigkeit. In vielen industriellen Anwendungen werden diese Stähle ge-schweißt. Die Schweißbarkeit wird weitgehend durch die chemische Zusammensetzung be-stimmt. Legierungen mit ferritischer oder ferritisch-austenitischer Erstarrung weisen die höchste Widerstandsfähigkeit gegen Heißrissbildung auf. Das resultierende Phasengleichge-wicht beeinflusst die endgültigen Eigenschaften des Bauteils. Daher kann es von Vorteil sein, den Ferritgehalt des Schweißguts vorherzusehen bzw. zu messen. Das neueste und präzi-seste Gefügediagramm ist das WRC-1992 Diagramm und basiert auf der chemischen Zusam-mensetzung der Grund- und Zusatzwerkstoffe. In diesem Diagramm kann vor dem Schweiß-prozess abgeschätzt werden, welche Volumenanteile von Ferrit und Austenit im resultierenden Schweißgut vorliegen werden. Genutzt wird es bei der schweißtechnischen Verarbeitung von nichtrostenden, austenitischen bzw. Duplex-Stählen. Verschiedene Quellen berichten, dass diverse Legierungselemente nicht berücksichtigt werden und Optimierungen nötig sind. Wei-terhin können Legierungselemente während des Schweißens abdampfen, was die Mikrostruk-tur zum Negativen beeinflusst. Diese Arbeit eruiert zunächst die theoretischen Grundlagen zur laserinduzierten Plasmaspekt-roskopie (LIBS, engl.: laser induced breakdown spectroscopy), die zur in situ Messung chemi-scher Konzentrationen während des Schweißens genutzt werden soll. Weiterhin werden die Grundlagen zur Erstarrung und zur Schweißbarkeit von DSS aufgezeigt. Mithilfe verschiede-ner Kalibriermodelle werden quantitative Messungen mittels LIBS ermöglicht. Um die Ergeb-nisse der LIBS-Analysen zu validieren, wurden Schweißproben angefertigt und LIBS-Messun-gen mit konventionellen Messmethoden, wie die Röntgenfluoreszenzanalyse (RFA) und die energiedispersive Röntgenspektroskopie (EDX) verglichen. Folglich wurden dann in situ LIBS-Versuche, während des Wolfram-Inertgas-Schweißens (WIG), mit und ohne Schweißzusatz-werkstoff durchgeführt. Hierbei konnten die chemischen Konzentrationen in der Schweißnaht mittels LIBS mit der gleichen Genauigkeit wie die konventionellen Verfahren gemessen wer-den. Ein weiteres Ziel dieser Arbeit ist es, die Gültigkeit und Vorhersagegenauigkeit des WRC-1992 Diagramms zu überprüfen. Hierfür wurde der Schweißzusatzwerkstoff mittels PVD-Be-schichtung mit den Legierungselementen Kohlenstoff, Nickel, Mangan, Silizium, Niob und Kup-fer beschichtet. Diese Elemente nehmen maßgeblich Einfluss auf das Phasengleichgewicht Austenit/Ferrit im Schweißgut der Duplexstähle, da sie entweder Ferrit- bzw. Austenitstabilisa-toren sind. Die Messung der ferritischen und austenitischen Phasenanteile im resultierenden Schweißgut wurde mit drei verschiedenen Methoden vergleichend durchgeführt. Mithilfe der Bildanalyse im Lichtmikroskop, einem Fischerscope® sowie der Röntgendiffraktion (XRD). Da-mit sollte auch geprüft werden, inwieweit die Verwendung der jeweiligen Messmethode die Aussagekraft des WRC-1992 Diagramms beeinflusst. Die Vorhersage anhand des WRC-1992 Diagramms war für Nickel, Silizium und Mangan akzeptabel, jedoch bei Niob, Kupfer und Koh-lenstoff waren deutliche Abweichungen zu beobachten. Anpassungen im WRC-1992 Dia-gramm sollten daher für die Elemente Niob, Kupfer und Kohlenstoff vorgenommen werden. Die geringste Genauigkeit und die größte Streuung wurden mit dem XRD-Verfahren erzielt. Daher kann dieses Verfahren für Ferritmessungen an Schweißnähten von Duplexstählen nicht empfohlen werden. KW - LIBS KW - Duplexstahl KW - Vorhersage Phasenanteile PY - 2025 SP - 1 EP - 118 AN - OPUS4-62622 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Reichel, Levin A1 - Kromm, Arne A1 - Schröpfer, Dirk A1 - Kannengießer, Thomas T1 - Moderne Schweißverfahren zur Optimierung von Reparaturschweißungen an hochfesten Offshore-Stählen N2 - The successful energy transition in Germany will require offshore wind turbines with outputs >10 MW in the future, for which high-strength steels with a yield strength of up to 500 MPa and wall thicknesses up to 150 mm are increasingly being used. The repair of weld seams when detecting defects during NDT requires local-ized gouging and rewelding. This involves high demands on welding manufacturing, especially for high-strength steels. Due to a lack of investigations, there are no re-pair concepts and information in standards and guidelines, particularly for high-strength thick plate joints made of high-strength offshore steels. However, these are urgently needed to enable processors, especially SMEs, to carry out safe and eco-nomical repairs. Therefore, BAM started the FOSTA project P1629 (IGF 01IF22746N) to investigate the stress-optimized repair (local gouging and welding) of high-strength thick plate joints made of offshore grades in the yield strength range off 355 to 460 MPa and similar weld metal with controlled high-performance GMAW processes and optimized narrower gouging grooves. The experimental analyses consider the complex interaction of material, process, and design-related influences on the formation of weld-related stresses and the special microstructure of high-strength fine-grain structural steels. Welding-related material degradation and crack-critical residual tensile stresses need to be avoided to ensure high component safety and performance. With component-related welding experiments on special testing equipment, adapted process and heat control concepts along with variable groove configurations will be developed and recommendations for guidelines elabo-rated. This is the prerequisite for fully utilizing the strength potential of high-strength steels and making a valuable contribution to the energy transition in Germany, espe-cially for steel-processing SMEs. T2 - Symposium Materialtechnik TU Clausthal CY - Clausthal-Zellerfeld, Germany DA - 19.02.2025 KW - Reparaturschweißen KW - Thermisches Ausfugen KW - Offshore KW - Sprühlichtbogen KW - Eigenspannungen PY - 2025 AN - OPUS4-62630 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Komann, Steffen T1 - Managementsystem Guide der IAEA (TS-G-1.4) N2 - Es wird der Safety Guide der IAEA für das Managementsystem für den Transport radioaktiver Stoffe vorgestellt. Des Weiteren werden die BAM-Gefahrgutregeln für das Managementsystem erläutert. T2 - Informationsaustausch zur verkehrsrechtlichen Aufsicht bei der Beförderung radioaktiver Stoffe CY - Bonn, Germany DA - 04.02.2025 KW - Radioaktive Stoffe KW - Rückbau kerntechnischer Anlagen KW - Transport KW - Gefahrgut PY - 2025 AN - OPUS4-62654 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hajhariri, Aliasghar T1 - Enhancing efficiency and safety of LH2 storage for a cleaner future N2 - As the world moves toward decarbonization and a green energy transition, hydrogen is increasingly recognized as a key energy carrier. However, its characteristics include a low volumetric energy density, necessitating storage in a high-density form to enable efficient energy transfer. Liquefied hydrogen (LH₂) offers a solution by providing high gravimetric energy storage within a confined volume. However, cryogenic hydrogen presents significant technical and safety challenges that must be addressed. This presentation explores the safety aspects that impact the integrity of storage systems and provides practical data analysis alongside experimental results, contributing to a broader understanding of liquid hydrogen storage and transportation. T2 - Online Colloquium H2Safety@BAM CY - Berlin, Germany DA - 19.02.2025 KW - Multi-Layer Insulation KW - Cryogenic KW - Liquid Hydrogen KW - Heat transfer PY - 2025 AN - OPUS4-62611 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Terhedebrügge, Gabriel A1 - Prager, Jens T1 - How can SHM be applied in a quality assured and legally compliant manner? T1 - Wie kann SHM qualitätssicher und rechtssicher angewendet werden? N2 - Many SHM applications developed at universities and research institutions have not yet left the laboratory scale. Possible reasons for this include: - Real components and structures are often more complex than expected, - The POD (probability of detection) of the SHM system is usually difficult to determine, - The reliability of SHM systems is often unsatisfactory, and - The transition from recurring inspection to permanent monitoring with automated SHM systems fails due to existing safety regulations and testing standards. The workshop addresses these issues and aims to present solutions that facilitate the practical use of SHM. The solutions will be developed using real-world applications, such as those in the field of renewable energy. N2 - Viele SHM-Anwendungen, die an den Universitäten und Forschungseinrichtungen entwickelt wurden, haben den Labormaßstab noch nicht verlassen. Mögliche Gründe dafür sind, - dass reale Bauteile und Strukturen häufig komplexer sind als erwartet, - die POD (probability of detection) des SHM-Systems zumeist schwer bestimmbar ist, - die Zuverlässigkeit der SHM-Systeme oft nicht zufriedenstellend ist und - der Übergang von wiederkehrender Prüfung zur permanenter Überwachung mit automatisierten SHM-Systemen an vorhandenen Sicherheitsrichtlinien und Prüfvorschriften scheitert. Der Workshop greift diese Fragestellungen auf und soll Lösungsansätze aufzeigen, die den Einsatz von SHM in der Praxis erleichtern. Die Lösungen werden beispielhaft für reale Anwendungen, z.B. aus dem Bereich der erneuerbaren Energien, erarbeitet. T2 - SCHALL 25 CY - Dresden, Germany DA - 28.03.2025 KW - SHM KW - Legal aspects KW - Pressure vessels KW - SMART-tools KW - QI-Digital KW - Periodic inspection PY - 2025 AN - OPUS4-62909 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Griesche, Axel T1 - Laser-Induced Breakdown Spectroscopy (LIBS) for Hydrogen Measurements in Steel N2 - Laser-induced breakdown spectroscopy (LIBS) allows for a time and spatially resolved almost non-destructive in situ measurement of hydrogen in metals. A surface pretreatment is not necessarily needed. We measured quantitatively hydrogen in steel samples, which were charged either electrochemically or by high-pressure hydrogen gas and compared the results. Further, the feasibility of quantitative hydrogen line scan measurements was demonstrated by measuring hydrogen at water jet cut surfaces. The hydrogen concentrations measured with the help of LIBS were compared with CGHE measurements. It was observed that hydrogen can be reliably measured with LIBS for concentrations larger than 2 wt.-ppm. The results show that LIBS is a promising technique for time- and spatially resolved measurements of hydrogen in steel and steel weldments. Results of time-dependant hydrogen permeation experiments will also be presented. T2 - H2MSE 2025 CY - Siegburg, Germany DA - 11.02.2025 KW - LIBS KW - Hydrogen Measurements KW - Steel PY - 2025 AN - OPUS4-62561 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hübner, Martin A1 - Kromm, Arne A1 - Kannengießer, Thomas A1 - Dittmann, Florian A1 - Varfolomeev, Igor T1 - Effect of weld design on fatigue strength of welded components using LTT filler materials N2 - Low transformation temperature (LTT) filler metals are an innovative approach to reduce tensile residual stress in weld seams and the surrounding heat affected zone (HAZ). The reduced tensile stress leads to an improvement in the fatigue strength of welded components. LTT filler metals are characterized by a reduced martensite start temperature (Ms), which is close to room temperature because of their chemical composition. This paper focuses on the hybrid use of LTT filler metals, where the LTT filler is applied as an additional layer to conventional welds on fatigue-critical spots. Conventional gas metal arc welded longitudinal stiffeners are used as specimens and at the face ends of the stiffeners, a second LTT layer was added with various weld modifications. These modifications were achieved by changing the welding parameters such as welding speed and offset to the first layer. These samples were used to analyze shape, dilution and resulting Ms, residual stress and fatigue strength. The dilution and dilatometer verified Ms did not change significant, although the surface of the 2nd LTT weld seam was varying clear with each modification. However, the weld modification had a significant effect on the residual stress state and the fatigue strength. The X-ray determined residual stress in the HAZ became lower when the weld toe of the LTT layer was further away from the stiffener. The Fatigue strength is clearly dependent on the residual stress state. The lower the residual stress at weld toe, the higher the fatigue strength. All samples with LTT weld exhibit significantly higher fatigue strength values than conventionally single and double-layer welded samples. The results show that on the one hand LTT filler metals increase the fatigue strength, and on the other hand the impact of LTT fillers materials is not restricted to the dilution and Ms, the shape of the weld seam must also be considered. T2 - IIW Intermediate Meeting CII CY - Trollhättan, Sweden DA - 10.03.2025 KW - LTT (Low Transformation Temperature) KW - Residual stress reduction KW - Fatigue strength KW - High-strength steels KW - Welding PY - 2025 AN - OPUS4-62708 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Griesche, Axel T1 - In situ Measurement of Hydrogen in Steel using Laser‑induced Breakdown Spectroscopy (LIBS) N2 - The ISO 3690 standard “Determination of hydrogen content in arc weld metal” requires a thermal activation of the diffusible hydrogen in a piece of weld metal for the subsequent ex situ concentration measurement by carrier gas hot extraction CGHE or thermal desorption spectroscopy (TCD). Laser-induced breakdown spectroscopy (LIBS) offers a time and spatially resolved, almost non-destructive, in situ measurement of hydrogen at surfaces without sample preparation. We measured hydrogen in steels, which were charged either electrochemically or by high-pressure hydrogen gas and compared the results. Further, the feasibility of quantitative hydrogen line scan measurements with LIBS was demonstrated by measuring hydrogen at water jet cut surfaces. The hydrogen concentrations measured with the help of LIBS were compared with CGHE measurements. It was observed that hydrogen can be reliably measured with LIBS for concentrations larger than 2 wt.-ppm. The maximum hydrogen concentration achieved using electrochemical charging was 85.1 ppm. The results show that LIBS is a promising technique for time- and spatially resolved measurements of hydrogen in steels. T2 - 2025 European Winter Conference on Plasma Spectrochemistry CY - Berlin, Germany DA - 02.03.2025 KW - Hydrogen measurement KW - LIBS KW - Spatial resolution KW - Temporal resolution PY - 2025 AN - OPUS4-62699 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Czeskleba, Denis T1 - Numerical simulation of hydrogen diffusion in thick-walled S690 SAW joints: the role of microstructure-dependent diffusion vs. welding heat input N2 - S690 steels are increasingly employed in modern steel construction, including building, plant, and mobile crane applications, due to their high strength and weldability. Submerged arc welding (SAW) is commonly used for these thick-walled structures but poses a risk of delayed hydrogen-assisted cold cracking (HACC). The influence of microstructure-dependent diffusion coefficients (DH) on hydrogen accumulation and distribution during welding and cooling remains poorly understood. In this study, the HACC susceptibility of thermomechanically rolled (MC) and quenched and tempered (Q) variants of S690 steel was compared. Weldments were fabricated using SAW, followed by electrochemical hydrogen permeation tests to determine microstructure-specific DH. A numerical model was developed to analyze hydrogen diffusion as a function of temperature, time, and microstructure. Results showed that the MC-grade exhibited slightly faster hydrogen diffusion than the Q-grade. However, simulations indicated that higher welding heat input and increased plate thickness had a significantly greater impact on hydrogen retention than microstructure-dependent diffusion effects. These findings suggest that while differences in hydrogen diffusivity exist between S690MC and S690Q, microstructure-specific diffusion plays a minor role in HACC risk. Instead, proper control of welding parameters is crucial for mitigating HACC, particularly in thick-plate, multi-layer SAW joints. T2 - Cracking Phenomena in Welding and Additive Manufacturing, 5th Int. Conference CY - Trollhätten, Sweden DA - 12.03.2025 KW - Hydrogen Cracking KW - Submerged Arc Welding KW - Hydrogen Diffusion KW - Cold Cracking PY - 2025 AN - OPUS4-63126 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kaiser, Sebastian T1 - Evaluation of welding on in-service pressurized hydrogen pipelines by component testing N2 - Hydrogen transportation is fundamentally different from natural gas (NG) as it can be absorbed into the pipeline material. However, pipelines require frequent maintenance or repair, in some cases on or onto the pipelines while they are still under pressure. This in-service welding causes challenges for hydrogen operations. They can be roughly divided into: (1) possible austenitization of the inner pipe material exposed to hydrogen, and (2) welding itself with its temperature cycles. Both lead to a significant increase in hydrogen solubility/diffusivity of the materials. Fundamental investigations are required due to the missing service experience. The present study introduces a specially designed demonstrator concept for the assessment of the welding processing conditions. The mock-up was designed to enable temperature measurement during welding as well as ex-post extraction of samples for the quantification of the absorbed hydrogen. The necessary pressurized hydrogen volume was limited by the insertion of a solid cylinder. Welding experiments on the pressurized mock-ups (DN50 and DN200) have shown that the austenitization temperature is nearly reached on the inner surface of the pipeline. This corresponds to a significant hydrogen absorption of several ppm in the welded joint, especially for thin-walled pipelines. Nonetheless, a potential hydrogen assisted cracking was not identified. T2 - 24. Werkstofftechnisches Kolloquium CY - Chemnitz, Germany DA - 02.04.2025 KW - Pipeline KW - In-Service KW - Welding KW - Hydrogen PY - 2025 AN - OPUS4-62917 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Reichel, Levin A1 - Kromm, Arne A1 - Michael, Thomas A1 - Schroepfer, Dirk A1 - Kannengiesser, Thomas T1 - Modern welding processes for optimizing repair welding on high-strength offshore steels N2 - The successful energy transition in Germany will require offshore wind turbines with outputs >10 MW in the future, for which high-strength steels with a yield strength of up to 500 MPa and wall thicknesses up to 150 mm are increasingly being used. The repair of weld seams when detecting defects during NDT requires localized gouging and rewelding. This involves high demands on welding manufacturing, especially for highstrength steels. Due to a lack of investigations, there are no repair concepts and information in standards and guidelines, particularly for high-strength thick plate joints made of high-strength offshore steels. However, these are urgently needed to enable processors, especially SMEs, to carry out safe and economical repairs. Therefore, BAM startedthe FOSTA project P1629 (IGF 01IF22746N) to investigate the stress-optimized repair(local gouging and welding) of high-strength thick plate joints made of offshore grades in the yield strength range off 355 to 460 MPa and similar weld metal with controlled high-performance GMAW processes and optimized narrower gouging grooves. The experimental analyses consider the complex interaction of material, process, and designrelated influences on the formation of weld-related stresses and the special microstructure of high-strength fine-grain structural steels. Welding-related material Degradation and crack-critical residual tensile stresses need to be avoided to ensure high component safety and performance. With component-related welding experiments on special testing equipment, adapted process and heat control concepts along with variable groove configurations will be developed and recommendations for guidelines elaborated. This is the prerequisite for fully utilizing the strength potential of high-strength steels and making a valuable contribution to the energy transition in Germany, especially for steelprocessing SMEs. T2 - 6. Symposium Materialtechnik CY - Clausthal-Zellerfeld, Germany DA - 20.02.2025 KW - Narrow groove KW - Optimized repair welding KW - Modern welding processes KW - High-strength steel PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-636520 DO - https://doi.org/10.21268/20250507-5 SP - 3 EP - 15 AN - OPUS4-63652 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Reichel, Levin T1 - From conventional to narrow groove repair: Optimizing repair welding with modern welding processes for high strength offshore steels N2 - The successful energy transition in Germany will require offshore wind turbines with outputs >10 MW in the future. To achieve these high outputs, turbines far from the coast are required, featuring large subsea jacket structures (30 m up to 50 m) and tall towers (up to 200 m). High-strength steels with a yield strength up to 500 MPa and wall thicknesses of up to 120 mm are increasingly being used for these structures. During manufacture, weld defects detected by non-destructive testing (NDT) require localized repair (gouging and rewelding). To date, there is a lack of repair concepts and information in standards and guidelines. Therefore, BAM initiated the FOSTA project P1629 (IGF 01IF22746N) to investigate the stress-optimized repair (local gouging and welding) of high-strength thick plate joints made of offshore grades in the yield strength range off 355 to 460 MPa and similar weld metal. This research aims to develop a stress-optimized repair concept for thick plate joints, using controlled high-performance GMAW processes and optimized, narrow gouging grooves. Thermal and mechanical gouging are performed, allowing the groove configuration to be modified. Modern welding processes provide deep root penetration and focused energy input capable of welding narrow seams. The aimed residual stress reduction can be attributed to the lower input of weld metal due to the changes in groove configuration and to the reduction in heat input per layer due to the controlled arc process. The experimental analyses take into account the interaction of process, material, and design-related influences on the formation of weld induced stresses. Concluding with recommendations for guidelines elaborated for steel-processing SMEs. T2 - 78th IIW Annual Assembly and International Conference CY - Genoa, Italy DA - 22.06.2025 KW - Narrow groove KW - Optimized repair welding KW - Modern welding processes PY - 2025 AN - OPUS4-63651 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schröder, Nina T1 - Influence of various microalloying strategies on the mechanical properties of weld seams in S690QL steel N2 - Microalloying elements such as niobium (Nb) and titanium (Ti) play a crucial role in achieving the desired mechanical properties of quenched and tempered high-strength fine-grained structural steels with a nominal yield strength of ≥ 690 MPa. Current specifications for the chemical composition only define upper limits for these elements, providing manufacturers with some flexibility. However, even minor deviations in alloying concepts can significantly influence the resulting mechanical properties. Consequently, accurately predicting weldability and the integrity of welded joints becomes challenging or even unfeasible due to variations in composition and the associated microstructural changes. Potential adverse effects include the softening of the heat-affected zone (HAZ) or, conversely, localized hardening phenomena. To address these challenges, various microalloying strategies with different Ti and Nb contents are being systematically investigated for the first time using specially designed laboratory-cast alloys. Each alloying approach is based on the commonly used S690QL steel grade while maintaining consistent chemical composition and heat treatment parameters. T2 - 78th Annual Assembly and International Conference CY - Genoa, Italy DA - 22.06.2025 KW - HSLA KW - Digital Image Correlation KW - HAZ Softening KW - Impact Toughness KW - Microalloying influence PY - 2025 AN - OPUS4-63648 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Neumann, Martin T1 - Small modular reactor (SMR) - Prinzip und Potenzial N2 - Derzeit gewinnen Small Modular Reactors (SMR) im Bereich zwischen 30 und 300MW in der internationalen Community stark an Gewicht. Diverse Länder entwickeln diese Reaktorkonzepte und viele Länder (unter anderem die Schweiz) planen, diese einzusetzen. Dieser Vortrag beleuchtet das Prinzip und das Potenzial der SMR sowie Chancen und Risiken. T2 - Vortragsreihe am Sportgymnasium Davos CY - Davos, Switzerland DA - 06.03.2025 KW - SMR KW - Radioaktiv PY - 2025 AN - OPUS4-63434 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Czeskleba, Denis T1 - Numerical simulation of hydrogen diffusion in submerged arc multilayer welds as a tool for the evaluation of cold cracking resistance N2 - High-strength structural steels are increasingly used in modern steel construction for economic and design reasons, e.g., in building, plant or mobile crane construction. By using steels with higher yield strengths (≥690 MPa), significant weight reductions and lower processing costs can be achieved by reducing the wall thickness. For example, substituting S235J2 with S960QL can reduce weight by up to 78%. Current efforts in lightweight design result from the goal of reducing greenhouse gas emissions by up to 65% by 2030 compared to 1990. These demands mean a significant reduction in process emissions in industry by increasing the efficiency of energy and raw materials. Submerged arc welding (SAW) offers high deposition rates and the welding of sheet thicknesses of up to 200 mm. Due to their special microstructure to achieve strength, high strength steels have reduced ductility and are susceptible to hydrogen-assisted cold cracking (HACC), which can also form with delay. In addition, large plate thicknesses lead to high residual welding stresses and long diffusion paths for hydrogen introduced via the welding process, for example. Numerical simulations provide a tool for evaluating the susceptibility of welded joints to cold cracking. In this study, the influence of heat input (ranging from 14.5 kJ/cm to 22 kJ/cm) and plate thickness (30 mm to 60 mm) on the hydrogen content in welded joints was investigated using the finite difference method. The simulation was parametrized to account for weld geometry, heat input and conduction, as well as hydrogen diffusion. Experimental investigations within the project determined hydrogen diffusion coefficients using electrochemical permeation. Additionally, the geometry of the weld layers was analyzed through macrosection examinations. These simulations showed that the heat input has a significant influence on the effusion of hydrogen and the distribution of the hydrogen concentration. Significant influencing factors are above all the sheet thickness and the thickness of the weld bead, as the hydrogen needs more time for effusion with longer diffusion paths. The simulation results can be used to derive HRHT diagrams and improve efficiency through process optimization. T2 - IIW Intermediate Meeting 2025 CY - Trollhätten, Sweden DA - 10.03.2025 KW - Hydrogen Cracking KW - Submerged Arc Welding KW - Hydrogen Diffusion KW - Cold Cracking PY - 2025 AN - OPUS4-63125 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Neumann, Martin T1 - Nuclear disposal - transport and storage of radioactive waste N2 - This presentation deals with transport, interim storage, and final disposal of radioactive material in Germany in the context of the University of Magdeburg course "Introduction to nuclear plant design and safety". The IAEA regulatory framework, relevant tests for ensuring safety, and transport packages are a major part of the transport aspect. Different interim storage designs are discussed as well as the current state of final repositories in Germany analyzed. Finally, a European perspective is given. T2 - Vorlesungsreihe "Introduction to nuclear plant design and safety" CY - Magdeburg, Germany DA - 13.06.2025 KW - Nuclear KW - Transport KW - Radioactive KW - Material PY - 2025 AN - OPUS4-63433 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nagelschmidt, Sven T1 - Application study of time-temperature correlation methods on test data of metal seals N2 - Reliable experimental data and prediction models are required to evaluate the behavior of components and materials over long periods of time. One method is based on the time-temperature equivalence principle, according to which a state or material property occurs or can be achieved equivalently at different time-temperature combinations. Higher temperatures generally shorten the duration and vice versa. Based on this approach, the long-term behavior of metal seals, as used in storage containers for spent nuclear fuels and high-level radioactive waste, has been studied at BAM and other institutions around the world for several years. However, such tests are often not planned as a preliminary point regarding the basic conditions of time-temperature related models. Gaps are then sometimes identified during the evaluation, for example because certain temperature values are missing, or the measurement intervals were not selected appropriately. This study evaluates exemplarily the status of the test data of metal seals at the BAM regarding the applicability of existing time-temperature correlation methods and corresponding models. Based on the existing database, the aim is to show which method and model are more likely to be applicable and which additional tests might be necessary to obtain a more suitable database. The tests so far have provided important findings for the planning and adaptation of possible further tests and for suitable model developments. Identified gaps in the data basis led to further development of the methods. In the present work, a time-temperature correlation was determined based on a time-temperature parameter from GRAHAM and WALLES for a selected data range. T2 - Pressure Vessels & Piping Conference PVP2025 CY - Montreal, Canada DA - 20.07.2025 KW - Time-temperature equivalence KW - Metal seals, KW - Time-temperature superposition KW - Time-temperature parameters PY - 2025 VL - 2025 SP - 1 EP - 4 PB - ASME CY - USA AN - OPUS4-63789 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ghaznavi, Ali A1 - Kästle, Emanuel D. A1 - Popiela, Bartosz A1 - Duffner, Eric T1 - Damage monitoring of hydrogen composite pressure vessels using acoustic emission technique and machine learning N2 - A good understanding of the structural stability of hydrogen composite overwrapped pressure vessels (COPV) is important for the cost-effective design and safe operation of hydrogen storage systems. Acoustic emission (AE) monitoring is a non-destructive method sensitive to microstructural damages such as e.g. fiber breakage, and matrix cracking in COPVs. This study proposes a novel approach for damage monitoring by integrating acoustic emission techniques with machine learning (ML) algorithms to classify and predict damage types in COPVs. However, training accurate classification models requires extensive labeled datasets, which are very challenging to generate due to the nature of AE signal data and the lack of in-situ observations of microscopic failures in COPVs. Our research overcomes this limitation by automating the labeling process of AE signal data for different COPVs using unsupervised ML methods. The most representative features were extracted and then selected from recorded AE signals. Different unsupervised clustering algorithms were utilized based on various extracted feature combinations. The most stable clustering result was achieved and later used as appropriate labels for training classification algorithms. A deep neural network-based deep learning (DL) architecture was used to train discriminative models on AE data, identify patterns, and classify damage types into different classes with improved accuracy and speed for each COPV. Results demonstrate the potential of the proposed combined deep learning approach to train predictive models in identifying failure patterns. The trained models based on individual COPVs show high training, validation, and test accuracy for unseen datasets and offer enhanced predictive capabilities by following advanced DL techniques compared to traditional monitoring methods. The proposed method highlights its potential to improve the efficiency and safety of hydrogen storage systems. T2 - SCHALL 25 CY - Dresden, Germany DA - 26.03.2025 KW - Sequential Neural Network KW - Acoustic Emission KW - Composite Overwrapped Pressure Vessels KW - Damagemonitoring KW - Machine Learning KW - Deep Learning KW - Deep Neural Network PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-629040 DO - https://doi.org/10.58286/30958 SP - 1 EP - 12 AN - OPUS4-62904 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Karapanagiotis, Christos T1 - Toward a Digital Twin of Hydrogen Pressure Vessels Enabled by Distributed Fiber Optic Sensors N2 - We present a digital replica of a hydrogen pressure vessel enabled by distributed fiber optic sensors (DFOS). This digital replica dynamically displays and updates the vessel’s structural condition by calculating strain residuals defined as the difference between the measured DFOS strain and the expected strain based on pressure data. As an example, we show the ability of the DFOS to detect and localize damage caused by drilling six holes into the vessel’s body. This digital replica represents a foundational step toward a fully integrated digital twin for predictive maintenance and remaining lifetime prognosis. T2 - Sensor and Measurement Science International 2025 CY - Nuremberg, Germany DA - 06.05.2025 KW - Fiber optic sensors KW - Hydrogen KW - Digital twins KW - Structural health monitoring KW - Machine learning KW - Predictive maintenance PY - 2025 AN - OPUS4-63087 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Popiela, Bartosz A1 - Günzel, Stephan A1 - Schukar, Marcus A1 - Mair, Georg W. A1 - Krebber, Katerina A1 - Seidlitz, Holger T1 - Impact of internal pressure control during manufacturing on residual stresses and safety performance of type 4 pressure vessels N2 - Composite pressure vessels are commonly manufactured using the wet filament winding process, where various process parameters can influence the performance of the finished component. In this study two designs of wet filament wound 6.8-liter type 4 composite pressure vessels were manufactured. Both differ only by the internal pressure used during the filament winding, which primarily influences the residual stress state in the composite structure. An extensive experimental study was carried out, including 10 slow burst tests and strain measurements with fiber optic sensors. Significant differences can be observed in the performance of the two designs even though the used stacking sequence, materials and other manufacturing parameters are the same for both designs. A discussion of the differences in the behavior of both cylinder types is provided, including the strain distribution in slow burst tests and failure mechanism. KW - Residual stresses KW - Slow burst tests KW - Filament winding KW - Type 4 composite pressure vessels KW - Hydrogen PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-626663 DO - https://doi.org/10.1016/j.jcomc.2025.100581 SN - 2666-6820 VL - 17 SP - 1 EP - 9 PB - Elsevier B.V. CY - Amsterdam, Netherlands AN - OPUS4-62666 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Popiela, Bartosz T1 - Creep Phenomena During Initial Loading of Type 4 Composite Pressure Vessels N2 - A poster presentation on the impact of creep phenomena during initial loading on the safety of type 4 composite pressure vessels. A statistical evaluation of slow burst tests shows an increase of the survival rate of initially loaded composite pressure vessels (sustained load and increased pressure) compared to the ones tested in a brand-new state. T2 - ASME Pressure Vessels & Piping® Conference CY - Quebec, Canada DA - 20.07.2025 KW - Composite KW - Pressure vessel KW - Safety KW - Creep PY - 2025 AN - OPUS4-63761 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Chaudhuri, Somsubhro T1 - WTB-IRT: Modelling and Measurement of Thermal Contrast in wind turbine rotor blades (WTBs) N2 - To understand the results that can be obtained with thermography of operational wind turbine blades, a climate chamber based experiment was performed. The results of these experiments were additionally modelled using COMSOL Multiphysics. The results have been presented at the conference. T2 - Advanced Infrared Technology and Applications (AITA) 2025 CY - Kobe, Japan DA - 15.09.2025 KW - Thermography KW - Thermografie KW - Wind turbine rotor blades KW - Windenergie Anlage Rotorblätter KW - FEA PY - 2025 AN - OPUS4-64222 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - VIDEO A1 - Popiela, Bartosz T1 - Better with age? Discussion of creep phenomena during initial loading of type 4 composite pressure vessels N2 - A video for the Rudy Scavuzzo Student Paper Competition at ASME PVP 2025. The topic of the presentation is the impact of creep phenomena during initial loading on the safety of type 4 composite pressure vessels. T2 - ASME Pressure Vessels & Piping Conference (ASME PVP 2025) CY - Quebec, Canada DA - 20.07.2025 KW - Composite KW - Pressure vessel KW - Safety KW - Creep PY - 2025 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-63763 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -