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 - Rashidi, Reza A1 - Vaerst, Olivia A1 - Riechers, Birte A1 - Rösner, Harald A1 - Wilde, Gerhard A1 - Maaß, Robert T1 - Atomic-scale strain fluctuations as an origin for elastic microstructures in metallic glasses N2 - Metallic glasses (MGs) exhibit an elastic microstructure that spans from a few to hundreds of nanometers, the origin of which continues to remain poorly understood. Here we employ four-dimensional scanning transmission electron microscopy (4D-STEM) on a Zr65Cu25Al10 (at. %) bulk MG. Mapping local diffraction patterns over representative areas also probed elastically with automated nanoindentation, two comparable correlation length scales have been identified. Specifically, local diffraction patterns are analyzed with respect to their ellipticity, revealing systematic fluctuations between positive and negative volumetric strains. A power spectrum analysis of the strain fluctuations returns a dominant length scale of the order of 100 nm, which is very much compatible with what elastic property mapping indicates. Annealing reduces the magnitude of the statistical strain fluctuations, without strongly affecting the associated fluctuation length scale. These findings demonstrate that atomic-scale strains are very likely the origin of the structurally unexpected large elastic fluctuations obtained in nanoscale contact mechanics experiments. KW - Metallic glass KW - 4D-STEM KW - Strain anisotropy KW - Nanoindentation KW - Elastic microstructure KW - Heterogeneities PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-654991 DO - https://doi.org/10.1016/j.actamat.2026.121982 SN - 1359-6454 VL - 308 SP - 1 EP - 8 PB - Elsevier Inc. AN - OPUS4-65499 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 - Wiesner, Yosri A1 - Eisentraut, Paul A1 - Altmann, Korinna T1 - One Year Observation of Microplastic Concentrations in the River Rhine N2 - In recent years, the quantification of microplastics (MP) in aquatic environments has gained increasing attention, particularly regarding their environmental distribution and potential exposure levels. Environmentally relevant exposure data are still essential for a realistic risk assessment of the harmful health potential of microplastics in freshwater systems. This study addresses a large data set of MP concentrations analyzed and processed under statistical aspects and provides mass concentrations as well as associated size fractions of the detected MP. Over a 12 month period, samples were collected at three locations and analyzed across three particle size fractions (100−500 μm, 50−100 μm, and 10−50 μm) using thermalextraction desorption-gas chromatography/mass spectrometry (TED-GC/MS). The most prevalent polymers identified were polyethylene (PE), polypropylene (PP), polystyrene (PS), styrene−butadiene rubber (SBR), and natural rubber (NR). Statistical analyses, including principal component and cluster analysis, revealed size-dependent patterns,minor seasonal variation and spatial variations. These findings are particularly significant for ecotoxicological research and regulatory development, especially regarding tire abrasion a rarely quantified but potentially harmful MP source. The study contributes aluable data for future environmental monitoring and supports EU directives on wastewater and drinking water quality KW - TED-GC/MS KW - Microplastics KW - Environment KW - Monitoring KW - Reference data PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-654669 DO - https://doi.org/10.1021/acsestwater.5c00530 SN - 2690-0637 SP - 1 EP - 10 PB - American Chemical Society (ACS) AN - OPUS4-65466 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 -