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Geometrically non-linear large planar deformations of shear deformable beams: Derivation, approximation, and numerical validation using Finite Element analysis
No full textIn this paper, we present derivations for the dynamic equations of motion of a shear deformable beam undergoing geometrically non-linear large deformations in a single plane. In the static case, these governing equations are given by six coupled, non-linear ordinary differential equations of first order which we present in the Lagrangian frame of reference and henceforth refer to as the Brunk–Herbrich–Weckner (BHW) beam theory. We confirm analytically that under pure bending an initially straight beam deforms into a circle, a known bench-mark solution. Next, we confirm numerically that our results agree well with the commercial Finite-Element code Abaqus for several example problems with increasing complexity, including the effect of axial preload as well as varying property domains along the beam. Abaqus is regarded as the state-of-the-art for non-linear structural analysis within the aerospace industry. Next, we show that the well-known Timoshenko–Ehrenfest and Euler–Bernoulli beam theory can be obtained from the general Brunk-Herbrich-Weckner beam theory in the limit of small deformations. Finally, we introduce the Iterative Projection Method which improves the results of the linearized Timoshenko–Ehrenfest beam theory without the computational cost associated with the fully non-linear analysis for all numerical test cases considered
Uncovering Li-ion Battery Degradation: Possibilities Offered by GD-MS Analysis
No full textUncovering Li-ion Battery Degradation: Possibilities Offered by GD-MS Analysis
Since their introduction, lithium-ion batteries (LIBs) have revolutionized the energy storage market, which they now dominate thanks to their high energy density, power capability, and efficiency.1, 2 Despite widespread adoption, global demand for LIBs is projected to grow by around 27% per year.3 This raises concerns about the availability of critical minerals essential to LIB production. Meeting future demand will therefore require next-generation LIBs—an ambition that hinges on a deeper understanding of the degradation processes that limit performance and lifetime.
Because LIBs are chemically and physically complex systems, capacity fade stems from multiple degradation phenomena that act concurrently as cells age.4 In particular, the formation and growth of interfacial layers at the electrodes during repeated charge–discharge cycling make a substantial contribution to component degradation.5
Glow Discharge Mass Spectrometry (GD-MS) offers depth-resolved elemental and isotopic analysis of battery electrodes and has proven to be a powerful tool for tracking degradation in LIBs. Using a ASTRUM Swift GD-MS spectrometer, we identified degradation pathways in both cathodes and anodes across various cell chemistries, linking electrochemical behavior with changes in structure and elemental distributions. These insights help clarify the mechanisms that accelerate aging and capacity loss
Herausforderungen beim Instandsetzungsschweißen von Altstahl – vom Werkstoffverhalten zur Schweißpraxis
No full textAus Gründen der Nachhaltigkeit und Wirtschaftlichkeit ist in der stahlverarbeitenden Industrie ein deutlicher Trend zum Bauen im Bestand zu beobachten, um kostenintensive Sperrungen oder Rückbaumaßnahmen zu vermeiden. Obwohl das Schweißen als effizientes und wirtschaftliches Fügeverfahren gilt, findet es im Zusammenhang mit Altstählen bislang nur begrenzt Anwendung. Stattdessen werden häufig Nieten- oder Schraubenverbindungen eingesetzt, die jedoch in vielen Fällen als unwirtschaftlich einzustufen sind.
Für Instandsetzungsmaßnahmen ist es häufig erforderlich, beschädigtes Bestandsmaterial durch moderne Stähle zu ersetzen oder Verbindungen zwischen Alt- und Neumaterialien herzustellen. Aufgrund der unterschiedlichen Herstellungsverfahren und Legierungskonzepte historischer Stähle ist jedoch nicht jeder Stahl aus dem 20. Jahrhundert ohne Weiteres schweißgeeignet. Daher ist zunächst eine systematische Prüfung der Schweißeignung erforderlich.
m Rahmen der vorliegenden Untersuchungen wurden verschiedene Altstähle hinsichtlich ihres Schweißverhaltens mittels Dilatometrie analysiert. Darüber hinaus wurden Schweißuntersuchungen an Mischverbindungen zwischen Altstahl und einem modernen Baustahl durchgeführt, um das Schweißverhalten und mögliche Gefügeveränderungen in der Übergangszone detailliert zu bewerten. Ziel war es, eine umfassende Datenbasis aus Schweiß-Zustands-Zeit-Diagrammen sowie Simulationen der Wärmeeinflusszone zu erstellen, um praxisrelevante Schweißuntersuchungen ableiten zu können. Diese Untersuchungen liefern wesentliche Erkenntnisse über das schweißmetallurgische Verhalten und die Schweißeignung der untersuchten Altstähle sowie deren Kombination mit modernen Werkstoffen.
Die gewonnenen Grundlagen bilden eine wichtige Basis für die Entwicklung innovativer schweißtechnischer Konzepte zur beanspruchungsgerechten Instandsetzung und Erhaltung bestehender Altstahl-Infrastrukturen in Deutschland
Systematik und Gefügearten nichtrostender Stähle
No full textDer Vortrag erläutert die Bezeichnungssystematik nichtrostender Stahlsorten und stellt verschiedene Gefügearten und deren spezifische mechanisch-technologischen Eigenschaften gegenüber
In situ Measurement of Hydrogen in Steel using Laser-induced Breakdown Spectroscopy (LIBS)
No full textLaser-induced breakdown spectroscopy (LIBS) is an analysis technique that allows contactless and fast in situ measurements of hydrogen in welded steels. The surface does not need necessarily be prepared as the laser can ablate material before the measurement. Depth profiling, point measurements as well as scanning of areas (mapping) can be utilized and automated. The method can be used for quantitative measurements, which requires a calibration with standards of similar material containing known hydrogen concentrations. LIBS is a candidate for ISO 3690, determination of diffusible hydrogen in martensitic, bainitic, and ferritic steel weld metal using arc welding processes with filler material. The capability of the method is shown in a hydrogen diffusion experiment
Wetting Interactions Between Porous Carbon Hosts and Liquid Sodium‐Potassium Alloys Toward Their Use in Negative Electrodes of Alkali‐Metal Batteries
No full textBatteries with liquid alkali‐metal negative electrodes offer a route to compact, high‐performance energy storage. Innovation in alkali‐metal management, i.e., controlled storage, release and transport of liquid alkali metal, can enable simpler and cheaper cell designs. Porous carbons have emerged as potential host materials for liquid alkali metals. Here, X‐ray computed tomography is used to study the wetting interactions between porous carbon hosts and liquid sodium‐potassium alloy (NaK) as a function of carbon host morphology and surface functionalization. While as‐received carbon samples show no affinity toward NaK, heat‐treated carbon is spontaneously infiltrated with NaK filling almost the entire pore volume. It is explored how forced wetting partially fills pores of NaK‐repellant hosts, showing large differences in pore filling based on the average pore size of the host material. In electrochemical discharge experiments, it is shown that both as‐received and heat‐treated carbon felt enable high areal capacities beyond 40 mAh cm−2. However, the heat‐treated carbon shows ten times lower overpotential. Finally, it is demonstrated how heat‐treated carbon felt can enable capillary transport of NaK. In summary, this study elucidates important aspects of the interactions between liquid alkali metals and porous carbon hosts, generating insights into possible applications in liquid alkali‐metal batteries
Challenges in microplastics standardisation
No full textThis talk addresses the challanges in microplastic analytics. It shows the need of standards, analytics and reference materials for accurate and reliable measurements. It explains the state of the art for referenence materials in this field and their problems. A solution is presented with PET tablets. The urgent need of harmonisation it also emphasised
Comparability issues of test specimens in laser powder bed fusion - how to consider differences in thermal history of complex components and primitive test specimens
No full textThe capability to produce complexly and individually shaped metallic parts is one of the main advantages of the laser powder bed fusion (PBF-LB/M) process. However, the thermal history during additive manufacturing of complex components can differ significantly from the thermal history of geometrically primitive test specimens. This can result in divergent microstructures and resulting mechanical properties. It drastically limits the comparability of different built parts and requires expensive full component testing. Moreover, the thermal history as the spatiotemporal temperature distribution has been identified as a major cause for flaw formation. Therefore, it can be hypothesized that a similar thermal history between components and test specimens enhances their comparability. In this talk, the concept of representative test specimens is introduced, which enables the transfer of thermal histories from complex geometries to simple geometries, which can lead to better comparability of material properties
A Customizable Procedure for Predicting Antibiotic Resistance Selection on Novel Antimicrobial Coatings
No full textThe global burden of antimicrobial resistance (AR) has manifested in an increasing number of deaths attributable to antibiotic-resistant bacteria (ARB) in recent years, with projections indicating a continued rise. Combating AR requires a multifaceted approach, one aspect of which involves preventing the spread of ARB in hospital environments via high-touch surfaces, which are known contributors to nosocomial infections. In conjunction with routine disinfection protocols and infection prevention measures, antimicrobial surfaces or antimicrobial coatings (AC) are increasingly being investigated and implemented to reduce microbial transmission via high-touch surfaces, thereby mitigating their spread in healthcare settings. However, similar to antibiotics, prolonged use of such surfaces may lead to the direct or indirect selection of ARB. To prevent this, targeted tests must be developed to predict potential AR selection before AC implementation.
Materials and Methods
As part of the Horizon-Europe-funded project "STOP" (Grant Agreement ID: 101057961), a novel antimicrobial coating is being developed and tested to reduce pathogen transfer on surfaces without selecting for ARB. To this end, two bacterial libraries (80 strains each) were assembled from the two species most associated with AR-attributable mortality worldwide, Escherichia coli and Staphylococcus aureus, as identified in the most recent comprehensive study [1]. Each library maintains a 50/50% ratio of strains resistant or sensitive to third-generation cephalosporins (E. coli) and methicillin (S. aureus), respectively—representing two of the most widespread resistance profiles. An adapted ISO 22196 method was developed using a reference benchmark antimicrobial surface (i.e., copper), with stainless steel serving as a control. The goal was to infer potential advantages of copper-unrelated antibiotic resistance phenotypes on the tested surface.
Results
Metadata, genomic data, and antibiotic susceptibility testing (AST) data were collected for all selected strains in each library, ensuring diversity in sequence types (ST) of clinical relevance, antibiotic resistance gene profiles, and geographical origins. The method was calibrated on copper surfaces using a reference E. coli strain, establishing the initial parameters required for investigators to customize the test for a given AC. Procedural reproducibility was assessed by comparing results from independent operators.
Discussion
The two libraries are currently being screened against the selected copper surfaces to identify potential associations between the resistance phenotypes of the tested species and their observed survival rates post-exposure. Three mutually exclusive outcomes are anticipated: (i) a statistically significant survival advantage of resistant strains compared to sensitive strains, (ii) an inverse scenario where sensitive strains exhibit higher survival, or (iii) no significant difference between the two groups. Furthermore, post hoc principal component analysis utilizing metadata and AST data may help elucidate genetic traits that confer a survival advantage on the tested AC.
Conclusions
This test aims to assist developers of antimicrobial coatings and materials in assessing potential selective pressures toward ARB before these products are implemented and evaluated under real-life conditions
Fiora: Source Data for Training and Testing
No full textThis repository contains source data for training and testing the Fiora model (see GitHub and DOI: 10.5281/zenodo.14651774). As part of the Fiora study (Nowatzky et al., 2025), which introduces a GNN-based fragmentation algorithm for simulating MS/MS spectra, this dataset enables the reproduction of the study’s findings and the training of new spectral prediction models