BAM-Publica - Publikationsserver der Bundesanstalt für Materialforschung und -prüfung
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Materials design using chemical heuristics, workflows, and machine learning
No full textBonds and local atomic environments are key descriptors of material properties, used to establish design rules and heuristics, and serve as descriptors in machine-learned interatomic potentials and the general machine learning of material properties.
Software implementations such as ChemEnv and LobsterEnv identify local atomic environments based on geometrical characteristics and quantum-chemical bonding analysis (here using Crystal Orbital Hamilton Populations as computed with LOBSTER). Fully automated workflows and analysis tools now enable large-scale quantum-chemical bonding analysis. The first part of the lecture will demonstrate how these tools help develop new machine-learning models and intuitive understandings of material properties.
New universal machine-learned interatomic potentials, such as MACE-MP-0, have been developed. The second part of the lecture will showcase how these potentials, combined with DFT, can accelerate research. It will focus on the interplay between DFT and machine-learned interatomic potentials, presenting automated workflows for training, fine-tuning, and benchmarking these potentials, implemented in our software autoplex. Additionally, it will show how to train new interatomic potentials from scratch by exploring potential energy surfaces, with the potential to enhance current universal machine-learned potentials.
The lecture will also discuss the trend toward automation in computational materials science and our recent contributions
Investigation of Shock Wave Propagation in Soft Tissue Simulants: An Analysis of Organic Gelatin and Synthetic Gel
No full textThis study investigates the effects of shock waves on soft tissue simulants, focusing on organic gelatin and a synthetic gel. Although extensive research has focused on the mechanical properties of soft tissue simulants, their behavior under shock wave conditions, such as those caused by blasts, is less understood. As explosives are increasingly used in modern combat scenarios, it is essential to study how shock waves interact with soft tissue. This knowledge is crucial for improving protective equipment and evaluating blast effects on the human body. A two-phase methodology was applied: First, organic gelatin production and synthetic gel composition were analyzed, identifying uncertainties and measuring sound speeds at varying temperatures to align with human tissue properties. Second, simulants were subjected to free-field shock waves, and embedded pressure sensors captured wave propagation, peak overpressures, and propagation velocity. Findings provide comparative insights into shock wave responses of simulants, offering a foundation for future experimental setups
Revealing the (positive) role of porosity within polymeric additively manufactured lattices via X-ray computed tomography
No full textThe mechanical properties of lattice geometries are known to be significantly influenced by a variety of manufacturing defects. This study investigates the influence of porosity on the mechanical behaviour of strut-based body-centred cubic (BCC) lattice structures produced with powder bed fusion with laser beam PBF-LB/P using PA2200 nylon powder. The study combines advanced techniques, including in-situ laboratory X-ray computed tomography (XCT), synchrotron XCT to visualise pores and roughness in high resolution at a single-cell level and image-based finite element analysis (FEA). The findings show that failure in thin-walled AM lattices is governed by the combined effects of porosity morphology, location, surface roughness, and cross-section reduction. The presence of internal porosity is found to attenuate both the amplitude of elastic modulus fluctuations and the severity of stress concentrations induced by surface irregularities
Aufgaben der BAM im Bereich Gefahrguttanks
No full textDie Präsentation gibt einen Überblick über die Aufgaben der BAM im Bereich der Gefahrguttanks. Dabei werden die Bereiche Zulassung, Beratung und Information und Forschung im Bereich der Tanks angesprochen
Production of a 1-10 μm polypropylene reference material for development of analytical methods
No full textThe poster is about the preparation of microplastics in the size range of 1-10 µm. These size range of particles can be inhalded and therefore be toxic for humans. The preparation is done by comminution of PP pellets and sieving. Characterisation occured for size with laser diffraction, for type with FTIR and for shape with SEM
Residual stress reduction using a low transformation temperature welding consumable with focus on the weld geometry
No full textLow transformation temperature (LTT) welding consumables represent an innovative approach to realize compressive residual stress in the weld seam and HAZ. LTT welding consumables use the volume-expanding martensitic phase transformation near room temperature to generate compressive residual stress during cooling. This article focuses on the weld geometry and its influence on residual stress reduction using an LTT welding consumable. For this purpose, layers with an LTT welding consumable were additionally applied to the front sides of conventionally welded longitudinal stiffeners. Different weld geometries of the second weld seam could be realized by varying the welding parameters. These samples were analyzed for geometric parameters, chemical composition, and residual stress. While the chemical composition and martensite start temperature (MS) were only slightly influenced by parameter changes, a clear influence with regard to residual stress and weld geometry was observed. Depending on the shape of the second LTT weld seam, residual stress reductions of 200 to 500 MPa were achieved using the same LTT welding consumable
Optimization of production process for microplastics reference materials
No full textMicroplastics (MP) are defined as plastic particles mainly consisting of polymers in the size range of 1 to 1000 µm. They can be found in a wide range of environmental matrices but also in food products, indicating a potential risk on humans and environment. Plastic debris in the environment or food chain are extremely complex in terms of size, concentration, polymer type, levels of physiochemical degradation and undefined morphologies which makes their isolation and detection in complex matrices challenging. Analytical detection methods and techniques to identify and quantify microplastics in environmental and food matrices are numerous but validated and standardized methods are currently lacking. To close this research gap, reference materials (RMs) and representative sample preparation approaches are urgently needed. Homogeneity and stability are two crucial characteristics for the certification process of the reference materials. For this purpose, we aim to present ways to prepare reference materials containing very low masses of close-to reality plastic particles with broad size distribution (10-100 µm) that are homogeneously distributed in tablet-to-tablet variation and stable over time. Our work is based on the ISO Guide 30:2015 and ISO Guide 35:2017 to fulfil the criteria set in future standards ISO/DIS 16094-2 and ISO/DIS 16094-3. The property of interest will be the mass detected by thermogravimetric analysis (TGA). Furthermore, informative values will be achieved by mass-based technique TED-GC/MS and spectroscopic microscopy techniques, such as µ-FTIR spectroscopy and µ-Raman
Digitale QI: Inspektion von Rotorblättern von Windenergieanlagen
No full textDer 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
Magnetism in iron alloys: methodological advances for thermodynamics, defects, and kinetics
No full textSteels are among the technologically and economically most relevant materials. Key innovations in important sectors of human society such as mobility, energy and safety, are currently based on alloying of Fe with other transition-metal elements such as Mn, Cr, or Co. Due to strong impacts and conceptual challenges related to magnetism, however, the fundamental understanding and the ability to computationally design these steels in high-throughput approaches lags behind other classes of alloys. In this article, we will provide a substantial review of the role of magnetism, magnetic excitations and transformations for alloy thermodynamics, point defects, interfaces and kinetics. This will be achieved by combining insights from different methods: Ab initio simulations have the advantage that the magnetic ground state is intrinsic part of the electronic minimization. Due to the coarsening of the many-electron structures and therewith magnetic interactions, tight-binding methods can handle larger system sizes. Effective interaction models provide the freedom to exploit more sophisticated magnetic interactions. The performance of these methods in terms of magnetic properties of Fe alloys will be evaluated by providing state-of-the-art results for their sensitivity to magnetism. Furthermore, dedicated experiments will be discussed to complete the understanding of magnetic effects in Fe alloys and to validate the modeling strategy
Multichannel real-time detection of biomarkers with highly miniaturized photonic microchips
No full textThe development of novel photonic integrated microchips (PIC) is a promising approach to allow for the convenient detection of key biomarkers in complex matrices through multichannel real-time analysis in a highly compact package. This study reports the successful development and application of a backside released CMOS chip designed for the multichannel real-time detection of biomarkers. Operating at the C-band at approx. 1550 nm, the microchip features three dedicated detection sensors in addition to a reference sensor, enabling simultaneous analysis of multiple biomarkers. The compact and highly miniaturized design of this microchip, with a footprint of just 1 mm², positions it as promising candidate for point-of-care diagnostics and personalized medicine applications. This technology opens a path to transform biomarker detection across various medical fields, offering rapid, reliable, and cost-effective diagnostic solutions. In conclusion, the presented multichannel photonic microchips signify a substantial leap forward in real-time biomarker detection, providing a highly capable platform for future research and clinical applications