TY - JOUR A1 - Nicolai, Marcel A1 - Bulling, Jannis A1 - Narayanan, M.M. A1 - Zeipert, Henning A1 - Prager, Jens A1 - Henning, Bernd T1 - Dynamic interface behavior in coupled plates: Investigating Lamb wave mode repulsion with a spring-based model N2 - This study investigates the phenomenon of mode repulsion in Lamb waves propagating through two coupled plates with an elastic interface. Using a spring-based coupling model and the Scaled Boundary Finite Element Method, the dispersion curves of the coupled system are analyzed under various interface conditions—weak coupling, sliding boundary, and perfect coupling. This research highlights how the mechanical stiffness of the interface influences the separation of modes and the emergence of repulsion regions. A novel focus on interface displacements reveals a unique dynamic behavior within the repulsion regions, driven by in-phase and out-of-phase oscillations of the coupled plates. The findings provide a physically grounded explanation of mode repulsion, linking it to the strain patterns in the interface. This insight lays the theoretical groundwork for future applications in material characterization and non-destructive evaluation, enabling more precise selection of Lamb wave modes for scientific and industrial purposes. KW - Lamb waves KW - Mode repulsion KW - Coupled plates KW - Elastic interface KW - Dispersion curves PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-642245 DO - https://doi.org/10.1016/j.ultras.2025.107799 SN - 0041-624X VL - 158 SP - 1 EP - 9 PB - Elsevier BV AN - OPUS4-64224 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - You, Yi A1 - Xue, Boyang A1 - Riedel, Jens T1 - Enhancement of LIBS plasma in air with organic solvent vapors N2 - Laser-induced breakdown spectroscopy (LIBS) offers versatile, field-deployable elemental analysis; however, compact, high-repetition-rate nanosecond laser systems typically face constraints in power consumption and size, often compromising emission intensity and thus analytical performance. We demonstrate a significant improvement in LIBS signals through the controlled introduction of common organic solvent vapors into a sheath gas, with a diode-pumped solid-state laser (1064 nm, 2–28 kHz repetition rate, 450–600-μJ pulse energy). Optical and acoustic diagnostics reveal up to ca. 40-fold enhancement of the N II emission line at 567 nm when ambient air serves as the analyte. Maximal enhancement occurs at intermediate repetition rates of ca. 15 kHz, particularly at pulse energies approaching the optical breakdown threshold; this observation suggests a viable strategy for operating LIBS at lower pulse energies and higher repetition rates. Enhancement effects scale jointly with both vapor pressure and ionization energy of the organic species, with acetone and toluene markedly outperforming methanol and isopropanol. These findings provide a rational foundation for significantly improving the analytical performance of portable LIBS instruments without exceeding platform-specific constraints. KW - LIBS PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-653758 DO - https://doi.org/10.1016/j.sab.2025.107309 SN - 0584-8547 VL - 236 SP - 1 EP - 6 PB - Elsevier B.V. AN - OPUS4-65375 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Holzer, Marco A1 - Johansen, Sidsel M. A1 - Christensen, Johan F.S. A1 - Smedskjaer, Morten M. A1 - Cicconi, Maria Rita A1 - de Ligny, Dominique A1 - Müller, Ralf A1 - de Camargo, Andrea S.S. A1 - Maaß, Robert T1 - Direct connection between secondary relaxation mode and fracture toughness in alkali-aluminosilicate glasses N2 - Oxide glasses are intrinsically brittle, lacking sufficient atomic-scale mechanisms that can relax mechanical stresses in the vicinity of a propagating crack. As a result, fracture is typically well-captured by considering local bond rupture at the crack tip. Here we demonstrate that barrier energies related to the low-temperature 𝛾-relaxation mode in alkali-aluminosilicate glasses are inversely related to the fracture toughness measured via standardized three-point bending fracture experiments. This holds true for both a series with varying cations (Li, Na, K) and one with varying Li concentration. The structural rationale for this finding is gained via Raman spectroscopy. The findings suggest that a fundamental structural relaxation mode measured on bulk specimens can serve as an effective guideline for fracture toughness of oxide glasses. Data for additional silicate glasses support this conclusion. KW - Fracture toughness KW - Oxide glass KW - Mechanical properties KW - Alkali-aluminosilicate glasses KW - Internal friction PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-651540 DO - https://doi.org/10.1016/j.mtadv.2025.100669 SN - 2590-0498 VL - 29 SP - 1 EP - 10 PB - Elsevier Ltd. CY - Amsterdam, Niederlande AN - OPUS4-65154 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fischer, Tim A1 - Huber, Norbert T1 - Microstructure and orientation effects on microcompression-induced plasticity in nanoporous gold N2 - Understanding the plastic deformation of nanoporous metals requires a detailed examination of their small-scale microstructural features. In this work, we present a computational study of micropillar compression in single crystal nanoporous gold (NPG) using crystal plasticity. This approach enables a systematic investigation of three key microstructural effects, including ligament size (50 ≤ 𝑙 ≤ 400 nm), solid fraction (0.2 ≤ 𝜑 ≤ 0.3), and initial crystal orientation ([001] and [111] ̄ ), on the plastic response far beyond yielding. After validation against experimental data, the study reveals that, in line with the ’smaller is stronger’ trend, besides the yield strength, the strain hardening rate also increases as ligament size decreases. Moreover, the strain hardening rate follows a power-law scaling with solid fraction, similar to the yield strength. The analysis of two distinct crystal orientations presents findings contrasting with previous assumptions. While the yielding onset remains orientation-independent, as expected, an increase in the strain hardening rate emerges for the harder [11-1] orientation with continued compression. An effect that becomes more pronounced with increasing solid fraction and decreasing ligament size. Under these conditions, harder orientations also amplify local stress heterogeneity. Notably, the stress distribution in NPG is nearly twice as wide as that observed in the single crystal bulk material (𝜑 = 1.0). Compared to the crystal plasticity approach, traditional isotropic plasticity predicts more uniform local stress fields. KW - Nanoporous gold KW - Microcompression KW - Plasticity KW - Size effect KW - Micromechanics PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-650137 DO - https://doi.org/10.1016/j.actamat.2025.121798 SN - 1359-6454 VL - 304 SP - 1 EP - 13 PB - Elsevier Inc. AN - OPUS4-65013 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Durlo Tambara, Luís Urbano A1 - Nikoonasab, Ali A1 - Radtke, Martin A1 - de Oliveira Guilherme Buzanich, Ana A1 - Gluth, Gregor T1 - Determination of the oxidation depths of ground granulated blast furnace slag-containing cement pastes using Mn K-edge X-ray absorption near-edge structure spectroscopy N2 - The redox potential of the pore solution of hardened cements containing ground granulated blast furnace slag (GGBFS) affects reinforcement corrosion and immobilization of radioactive waste. Here, Mn K-edge X-ray absorption near-edge structure (XANES) spectroscopy was applied to determine the depth profile of the oxidation state of manganese in hardened GGBFS-containing cement pastes. Manganese was oxidized in the outer regions of some of the pastes, but the depth to which this occurred was not identical with the ‘blue-green/white color change front’, usually interpreted as indicating oxidation of sulfur species. For CEM III/B, the color change of the material was gradual and thus unsuitable for a precise determination of the oxidation depth, while for the alkali-activated slag, a distinct color change front was found, but full oxidation of manganese and sulfur had not occurred in the brighter region. Mn K-edge XANES spectroscopy is thus a more reliable method than the determination of the visual color change front to follow the ingress of the oxidation front. KW - Manganese KW - Oxidation KW - Sulfide KW - Alkali-activated materials KW - Redox conditions PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-651469 DO - https://doi.org/10.1111/jace.70445 SN - 0002-7820 SN - 1551-2916 VL - 109 IS - 1 SP - 1 EP - 11 PB - Wiley CY - Oxford AN - OPUS4-65146 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Campari, Alessandro A1 - Konert, Florian A1 - Razavi, Nima A1 - Sobol, Oded A1 - Alvaro, Antonio T1 - Hydrogen-assisted cracking: A deep learning approach for fractographic analysis N2 - Hydrogen handling equipment suffers from interaction with their operating environment, which degrades the mechanical properties and compromises component integrity. Hydrogen-assisted cracking is responsible for several industrial failures with potentially severe consequences. A thorough failure analysis can determine the failure mechanism, locate its origin, and identify possible root causes to avoid similar events in the future. Postmortem fractographic analysis can classify the fracture mode and determine whether the hydrogen-metal interaction contributed to the component’s breakdown. Experts in fracture classification identify characteristic marks and textural features by visual inspection to determine the failure mechanism. Although widely adopted, this process is time-consuming and influenced by subjective judgment and individual expertise. This study aims to automate fractographic analysis through advanced computer vision techniques. Different materials were tested in hydrogen atmospheres and inert environments, and their fracture surfaces were analyzed by scanning electron microscopy to create an extensive image dataset. A pre-trained Convolutional Neural Network was finetuned to accurately classify brittle and ductile fractures. In addition, Grad-CAM interpretability method was adopted to identify the image regions most influential in the model’s prediction and compare the saliency maps with expert annotations. This approach offered a reliable data-driven alternative to conventional fractographic analysis. KW - Failure analysis KW - Fractographic analysis KW - Hydrogen embrittlement KW - Material compatibility PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-646610 DO - https://doi.org/10.1016/j.commatsci.2025.114366 SN - 0927-0256 VL - 262 SP - 1 EP - 16 PB - Elsevier Science CY - Amsterdam [u.a.] AN - OPUS4-64661 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tóth, Péter A1 - Hofmann‐Böllinghaus, Anja A1 - Dumont, Fabien A1 - Anderson, Johan A1 - Sjöström, Johan A1 - Bergius, Mikael A1 - Chiva, Roman A1 - Lalu, Octavian T1 - Finalisation of the European Approach to Assess the Fire Performance of Facades—Brief Information on the Outcome of the Project N2 - This research was conducted within the framework of project SI2.825082, funded by the European Commission—DG GROW. The project's objective was to finalise a European approach for assessing the fire performance of façades under medium and large fire exposure conditions. The national standards BS 8414‐1:2020/BS 8414‐2:2020 and DIN 4102‐20:2017 served as the foundation for developing the new assessment method. As part of the project, a theoretical round robin, initial testing activities and a large‐scale experimental round robin were carried out. The theoretical round robin aimed to examine how different laboratories interpreted the preliminary assessment method. Subsequently, the initial testing phase explored the design of the fire source, combustion chamber and secondary opening. The experimental round robin involved testing four façade systems across three laboratories using the assessment method documents, resulting in 12 tests for medium‐scale and 12 for large‐scale exposure—24 tests in total. These tests provided data to develop a calibration scheme and define appropriate performance criteria for classification. In this paper, the representatives of the project consortium summarise the research process and outline the proposed testing and evaluation methodology, which is intended to form the foundation of a future European testing standard for façades. The article also highlights the need for further research to establish rules for extended application of test results. KW - Facade KW - Testing PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-654731 DO - https://doi.org/10.1002/fam.70042 SN - 0308-0501 SP - 1 EP - 27 PB - John Wiley & Sons Ltd. AN - OPUS4-65473 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sobczak, M. A1 - Lecompagnon, Julien A1 - Hirsch, Philipp Daniel A1 - Pieczonka, Ł. A1 - Ziegler, Mathias T1 - Impact damage characterization on CFRP parts using laser line scanning active thermography N2 - This study presents a dual-path data processing framework for the detection and characterization of barely visible impact damage (BVID) in carbon-fiber-reinforced polymer (CFRP) structures using laser line thermography (LLT). A robotic LLT system was used to scan impacted CFRP specimens, and the resulting thermal sequences were analyzed using two complementary methods: full thermogram reconstruction followed by Pulse Phase Thermography (PPT) to detect subsurface delaminations, and Time-Summed Gradient Filtering (TSGF) to enhance surface-breaking cracks. Both processing paths produced interpretable results that were fused into a unified combined image and overlay mask, enabling simultaneous visualization of different defect types from a single scan. Quantitative analysis was performed on the binary masks to extract defect dimensions and Signal-to-noise ratio (SNR) values. The results demonstrated that delaminations and multiple cracks could be accurately detected and spatially distinguished, with good agreement to reference methods such as flash thermography and vibrothermography. This work highlights the potential of LLT as a versatile and scalable inspection technique, where multimodal defect detection and segmentation can be achieved through targeted processing and data fusion strategies. KW - Active thermography KW - CFRP KW - Laser line scanning KW - Delamination KW - Cracks KW - BVID KW - NDT PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-654097 DO - https://doi.org/10.1016/j.compositesb.2026.113425 SN - 1359-8368 VL - 313 SP - 1 EP - 9 PB - Elsevier Ltd. AN - OPUS4-65409 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröder, Nina A1 - Uhlig, Marvin A1 - Kromm, Arne A1 - Schröpfer, Dirk A1 - Höfer, Kevin A1 - Hensel, Jonas A1 - Kannengießer, Thomas T1 - Challenges in the evaluation of the weldability of old mild steels for future use N2 - For reasons of sustainability and cost efficiency, there is an increasing trend in the steel-processing industry to retrofit existing structures, avoiding costly shutdowns or dismantling. Although welding is a cost-effective joining method, it is rarely applied to old steels, whereas riveted or bolted connections are often uneconomical. Repair and refurbishment frequently require the replacement of damaged material or the creation of dissimilar old–new steel joints. Due to the varied manufacturing processes of historical steels, not all twentieth-century steels are inherently weldable, making an initial assessment of weldability essential. In this study, a historical non-deoxidized mild steel (produced by Siemens–Martin processing) originating from the construction of the Berlin Radio Tower (erected in 1926) was investigated using dilatometry to analyze its welding behavior. A database of welding CCT diagrams and HAZ simulations was established to support practice-oriented welding experiments, providing key insights into their weld-metallurgical behavior and weldability. Furthermore, initial welding trials were conducted, and the local residual stress states in dissimilar old–new steel joints were determined. These foundational investigations are critical for the development of innovative, load-adapted welding concepts for the repair and refurbishment of existing old-steel infrastructure in Germany. KW - Old mild steels KW - Repair welding KW - Weldability KW - Thermo-physical simulation KW - CCT diagrams PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-654784 DO - https://doi.org/10.1007/s40194-026-02366-6 SN - 1878-6669 SP - 1 EP - 14 PB - Springer nature AN - OPUS4-65478 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - George, Janine A1 - Ouellet-Plamondon, Claudiane A1 - Reyes, Kristofer T1 - Introduction to the “Accelerate Conference 2023–2024” themed collection N2 - The collection showcases the ways in which automation, machine learning and robotics are transforming experimental materials science and chemistry into continuous, computationally integrated processes. It features innovations regarding autonomous laboratories, Bayesian optimisation, high-throughput experimentation and computation, and AI-driven literature extraction, which simplify and scale up materials discovery. Together, these works outline a modular, responsible framework for accelerating scientific progress through human-guided, data-driven autonomy. KW - Automation KW - Materials Acceleration Platforms KW - Synthesizability KW - Workflows KW - Large Language Models KW - Ontologies KW - Materials Discovery PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-654658 DO - https://doi.org/10.1039/d5dd90057c SN - 2635-098X SP - 1 EP - 2 PB - Royal Society of Chemistry (RSC) AN - OPUS4-65465 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -