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Paper des Monats
- ja (32)
Any surface in the environment acts as hotspot for microbial attachment and activity. These biofilms represent the interface between humans and the environment.
While in the past biofilms were often seen as disturbance, we now start to understand the enormous potential of beneficial biofilms. They can be used in a broad range of applications and are sources for new microorganisms and traits. After all, biofilms represent a great example for a collaborative lifestyle.
Residual stress formation during repeated gouging and repair welding cycles of high-strength steels
(2024)
The construction of foundation and erection structures for wind power plants requires the use of modern, sustainable and resource-efficient high-strength fine-grained structural steels. Weld defects due to the welding process are unacceptable. To overcome this issue, local thermal gouging followed by re-welding is a common and cost-effective method. The high shrinkage restraint of the gouge by the surrounding structure can cause crack initiation when design and re-weld induced residual stresses are superimposed. This risk is intensified by the progressive degradation of the microstructure and mechanical properties of high-strength steels during the weld repair process.
This investigation focuses on high-strength steels S500MLO for offshore applications and S960QL for mobile crane applications. The reduction and development of residual stresses caused by local thermal gouging and re-welding was investigated. Digital Image Correlated (DIC) stress-strain analysis was performed during preheating, welding and cooling. The results of the global DIC analysis and local longitudinal and transverse residual stresses of the weld determined by X-ray diffraction were found to be in good agreement. Furthermore, different stress levels were identified during gouging and welding. Repeated repair cycles led to an increase of longitudinal and transverse residual stresses in the weld metal as well as a hardness increase in the heat affected zone.
Indirect combustion noise due to the interaction of flow inhomogeneities with a choked combustion-chamber exit is an important cause of combustion instability in solid rocket motors.
Moreover, it is believed to be an issue in electrical-power generation turbines and aero-engines. If these flow inhomogeneities are essentially characterized by the fluid having a locally appreciablydifferent thermodynamic state, the acoustic response engendered by its interaction with the combustion-chamber exit is commonly referred to as entropy noise. In this paper, dedicated numerical-simulation results of entropy-patch choked-nozzle interactions are presented. Two types of entropy patches were considered: rectangular slugs and circular spots. Moreover, analytical-model-based analysis, of said simulation results, is presented. Based on said analysis, the authors posit the existence of three modeling regimes: the quasi-steady-modeling regime, the blended-physical-effects regime, and the inertial-modeling regime.
Das Ausbreitungsverhalten geführter Ultraschallwellen ermöglicht die großflächige Prüfung von Platten und schalenförmigen Bauteilen wie Rohren und Laminaten auf Fehlstellen von wenigen Prüfpunkten aus. Während die beschränkte Divergenz der geführten Wellen die Ultraschallprüfung begünstigt, erschwert das dispersive und multimodale Verhalten der Lamb-Wellen die Auswertung der Ultraschallsignale. Die dispersive und multimodale Wellenausbreitung verkompliziert die Bestimmung der Fehlerposition bei der Auswertung der Geschwindigkeiten einzelner Wellenpakete. Zudem ist es herausfordernd, einen einfachen Zusammenhang zwischen den Reflexionen der Fehlstelle und deren Größe und Form herzustellen. Eine Möglichkeit zur genauen Bestimmung der Fehlerposition und -geometrie bietet der direkte Vergleich der Messsignale mit den Signalen aus einem Simulationsmodell. Die Nachbildung des Schadens im Simulationsmodell stellt ein inverses Problem dar, das iterativ gelöst werden kann, indem ein Vorwärtsmodell immer weiter optimiert wird. Klassische Ansätze wie die Finite Elemente Methode (FEM) sind für die Simulation von Ultraschallwellen aufgrund der kleinen Wellenlängen im Vergleich zur Bauteilgröße meist ineffizient. Aus diesem Grund basiert das vorgestellte Vorwärtsmodell auf der semi-analytischen Scaled Boundary Finite Element Method (SBFEM), die große Teile der Wellenausbreitung analytisch berechnet. In diesem Beitrag wird die Validierung des zweidimensionalen Modells an Platten mit einer rechteckigen Nut als Ersatzfehler präsentiert und es werden erste Schritte zur Validierung von 3D-Modellen vorgestellt.
This presentation provides an introduction and intermediate results of the Horizon-Europe STAR4BBS project.It focuses on how to maximize the potential of Sustainability Certification Schemes (SCS) and labels to support a successful transition to a sustainable bio-based economy by assessing their effectiveness, robustness, and credibility.
Trace elemental analysis in human serum is integral in both clinical and research settings. Analyzing the level of some specific elements like Se and Zn helps indicate the nutritional and health status. Furthermore, elucidating the roles of trace elements in various physiological and pathological conditions can shed light on disease mechanisms and potential treatments. Inductively coupled plasma mass spectrometry (ICP-MS) stands out as a preeminent method for trace elemental analysis, given its exceptional sensitivity and minimal sample requirements. However, ICP-MS has challenges, such as argon-related interferences that hinder the accurate quantification of elements like Ca, Fe, and Se. The naturally most abundant isotopes of Ca (40Ca), Fe (56Fe), and Se (80Se) are subject to isobaric interference from 40Ar+, 40Ar16O+, and 40Ar2+, thereby complicating their direct measurement and preventing isotope dilution analysis.
In response to these challenges, nitrogen microwave inductively coupled atmospheric pressure mass spectrometry (MICAP-MS) emerges as a viable alternative to ICP-MS, eliminating argon consumption and associated interferences. This study employed MICAP-MS to quantify Ca, Fe, and Se in 11 certified reference human serums using matrix-matched calibration and isotope dilution with the isotopes 40Ca, 56Fe, and 80Se. The results obtained with both methods were validated against certified values, and the suitability of MICAP-MS for isotope dilution was evaluated. Additionally, the performance of MICAP-MS in the Na matrix was investigated and discussed alongside the impact of organic species.
Das Ausbreitungsverhalten geführter Ultraschallwellen ermöglicht die großflächige Prüfung von Platten und schalenförmigen Bauteilen wie Rohren und Laminaten auf Fehlstellen von wenigen Prüfpunkten aus. Während die beschränkte Divergenz der geführten Wellen die Ultraschallprüfung begünstigt, erschwert das dispersive und multimodale Verhalten der Lamb-Wellen die Auswertung der Ultraschallsignale. Die dispersive und multimodale Wellenausbreitung verkompliziert die Bestimmung der Fehlerposition bei der Auswertung der Geschwindigkeiten einzelner Wellenpakete. Zudem ist es herausfordernd, einen einfachen Zusammenhang zwischen den Reflexionen der Fehlstelle und deren Größe und Form herzustellen. Eine Möglichkeit zur genauen Bestimmung der Fehlerposition und -geometrie bietet der direkte Vergleich der Messsignale mit den Signalen aus einem Simulationsmodell. Die Nachbildung des Schadens im Simulationsmodell stellt ein inverses Problem dar, das iterativ gelöst werden kann, indem ein Vorwärtsmodell immer weiter optimiert wird. Klassische Ansätze wie die Finite Elemente Methode (FEM) sind für die Simulation von Ultraschallwellen aufgrund der kleinen Wellenlängen im Vergleich zur Bauteilgröße meist ineffizient. Aus diesem Grund basiert das vorgestellte Vorwärtsmodell auf der semi-analytischen Scaled Boundary Finite Element Method (SBFEM), die große Teile der Wellenausbreitung analytisch berechnet. In diesem Beitrag wird die Validierung des zweidimensionalen Modells an Platten mit einer rechteckigen Nut als Ersatzfehler präsentiert und es werden erste Schritte zur Validierung von 3D-Modellen vorgestellt.
We present our approach and methodology for simulating piping erosion, which occurs during the installation process of suction bucket foundations for offshore wind turbines. We show several simulations and analyze the hydrodynamic and contact forces acting on the granular fabric and the differential pressure of the fluid phase. We demonstrate weak scaling performance on the LUMI supercomputer with a parallel efficiency of up to 90% for 4096 Graphics Compute Dies.
Self-healing polymers have been developed to improve durability and reduce costs associated with maintenance during service. The addition of thermoplastics to thermosets to produce mendable polymers appears as a promising selfhealing technique. In this study, poly (ethylene-co-methacrylic acid) (EMAA) was added to epoxy resin and the effects of EMAA addition on epoxy properties were evaluated. Specimens with two different contents of thermoplastic and particles sizes were manufactured. A two-level full factorial experimental design was used to evaluate the effect of particle size and particle content on properties of epoxy modified with addition of EMAA. Tensile tests and dynamic mechanical analysis (DMA) were used and the evaluated responses were tensile strength, modulus of elasticity, and glass transition temperature (Tg). X-ray computed tomography (XCT) was used to investigate particle size and concentration after manufacturing. It was found that the particle concentration has greater effects on stress–strain behavior of epoxy while Tg was not significantly affected by neither of the analyzed entrance variables.
The Microplastic Microbiome
(2024)
Microplastics represent man-made and newly emerging surfaces in our ecosystems, where they interact with microorganisms. The ecosystem in focus of this presentation will be the aquatic environment. It will be portrayed, which microorganisms use microplastics as a habitat, how environmental factors shape this colonization, and why the biodegradation of plastics in the ocean is an overall unlikely process. We will also discuss whether potentially pathogenic microorganisms use microplastics as a raft. Finally, possible adaptation mechanisms of plastic-colonizing microorganisms will be presented, such as the production of photoreactive molecules. The microplastic microbiome has a large potential to harbor so far unknown species with curious traits, representing an exciting research topic for the future.
Die Transformation der Energienutzung von konventionellen zu erneuerbaren Quellen führt dazu, dass zukünftig mehr Energie effizient zwischengespeichert werden muss. Eine Möglichkeit der elektrochemischen Zwischenspeicherung bieten Lithium-Ionen-Batterien. Hierfür können ausgemusterte Automobilantriebsbatterien verwendet werden. Erfüllen sie die hohen Anforderungen des mobilen Bereichs nicht mehr, haben sie oftmals noch eine ausreichende Kapazität und Leistungsfähigkeit für die stationäre Zwischenspeicherung.
Neben der Verwendung der Batterien im größeren Maßstab, z.B. bei Energieversorgern, werden durch den vermehrten Einsatz von Photovoltaik-Anlagen in Ein- und Mehrfamilienhäusern verstärkt Zwischenspeicher für Privathaushalte nachgefragt. Dies birgt auch für Einsatzkräfte neue Herausforderungen in der Gefahrenabwehr.
Im vom Bundesministerium für Bildung und Forschung (BMBF) geförderten Verbundprojekt „SEE-2L – Sicherheit elektrochemischer Energiespeicher in Second Life Anwendungen“ wurden Versuche mit Second Life Modulen durchgeführt. Verbundpartner im Projekt waren neben der vfdb die Otto-von-Guericke-Universität Magdeburg und die Bundesanstalt für Materialforschung und -prüfung. Zudem war das Institut der Feuerwehr Nordrhein-Westfalen eingebunden.
Die durchgeführten Versuche bilden eine Grundlage für die Einordnung der Batteriespeicher, z.B. aus Sicht des baulichen Brandschutzes, zur Methodik der Brandbekämpfung oder zur Risikobewertung hinsichtlich der Prozess- und Anlagensicherheit.
Im Beitrag werden die Versuchsergebnisse vorgestellt und Ansätze für deren Anwendung gezeigt. Um die gewonnenen Erkenntnisse zu vermitteln, wurde im Projekt zudem ein Schulungskonzept für Einsätze mit Lithium-Ionen-Technologien erarbeitet, das im Beitrag präsentiert wird. Es besteht aus theoretischen und praktischen Anteilen, sodass bei den Feuerwehren praxisnah aus- bzw. fortgebildet werden kann.
Lithium-ion batteries are a key technology for tackling challenges in energy and climate crisis, but up to 30 % are discarded right after production. Quality is closely related to the homogeneity of the used materials and coatings. Fluorine compounds, both in the polymer and from degradation of the electrolyte, are of special interest for the formation and aging of LIBs. Glow-discharge optical emission spectroscopy (GD-OES) emerged as a fast and convenient method for depth-profiling of battery materials. However, fluorine remains a spectroscopic challenge due to a high excitation energy and only few strong emission lines in the UV/Vis spectral range.
We investigated the partial substitution of argon with neon in the plasma gas. The main emission line at 685.603 nm was monitored by both photo multiplier tube (PMT) with Czerny-Turner monochromator at 20 µm slit-size, and charge-coupled device (CCD) with 1200 lines/mm grating. For calibration, we used a set of hot-pressed copper cylinders with varying calcium fluoride amount fraction, ranging from 1.6 % to 4.4 %. Plasma gas mixtures with a mole fraction of 5 %, 10 % and 20 % neon in argon were used. Sensitivity in comparison to pure argon was increased by factor 4, 7 and 14, respectively. In general, PMT detection was more sensitive than CCD. As expected, sputter rates decreased with higher neon content in the plasma gas. Depth-profiling of the cathodes was performed in pulsed mode at constant voltage and pressure, which resulted in stable plasma conditions. We achieve matrix-independent quantitative information on fluorine distribution by correction based on sputter rates.
This advancement in GD-OES provides a more accurate analytical approach for evaluating the homogeneity of lithium-ion battery materials, potentially leading to more sustainable and cost-effective manufacturing processes.
To address the challenges of the climate crisis, multiple solutions for sustainable energy sources and storage systems are needed. One such solution is lithium-ion batteries (LIBs). Currently, 5 to 30 % of LIBs are discarded immediately after manufacturing. The homogeneous distribution of all materials used in the coating of cathodes and anodes is critical for the quality of LIBs. Furthermore, during formation i.e., the first steps of the charge/discharge cycling, the solid-electrolyte interphase forms on the anode particles, which has a huge impact on the performance. The same happens to some extent on the cathode, forming the cathode-electrolyte interphase. Fluorinated polymers and electrolytes are used in the manufacturing of LIBs. The electrolyte in particular is prone to degradation during formation and aging of the batteries. The interface of the cathode material with the aluminum current collector is also a critical point where degraded fluorine components cause pitting corrosion and at the same time promote passivation of the metal foil. Monitoring the spatial distribution of fluorine on these surfaces and interfaces is essential for sustainable LIB production.
In order to reduce global warming, the use of hydrogen as a renewable energy source is becoming more important. To enable this transition, unprecedently large amounts of hydrogen need to be safely transported and stored. Since hydrogen is usually stored and transported under pressure, one scenario to be considered is the release of hydrogen from a leakage with subsequent ignition. The resulting jet flame must be characterized with respect to the thermal radiation emitted into the environment to define safety distances. Various models that characterize the resulting flame shape and radiation already exist in the literature, but these are mainly based on empirical data from hydrocarbon jet flames. To verify the applicability of these models to hydrogen, real-scale tests are carried out at the BAM Test Site for Technical Safety (BAM-TTS) with the aim to assess the flame geometry and the emitted thermal radiation. Parameters such as leakage diameter (currently up to 30 mm), pressure (currently up to max. 250 bar) and mass flow (up to max. 0.5 kg/s) are varied. In particular, the focus will be laid on the measurement and modelling of the thermal radiation. 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 literature are mostly based on unsteady outflow conditions. The experimental setup used here allows for the generation of a steady-state outflow for several minutes and thus a direct comparability with existing (steady-state) models. Furthermore, 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. Following from the experimental investigations, modelling parameters such as the Surface Emissive Power (SEP) and the radiant heat fraction for hydrogen and methane will be compared to literature data.
Science Café Adlershof is having its next edition in 2024 on February 20th '24! We will have one speaker next week: Alexander Winckelmann is a PhD student at Bundesanstalt für Materialforschung und -Prüfung and will give a talk about his stay abroad in Switzerland - there will be free chocolates! There will be enough time to ask questions or simply chat with the guests and participants.
Einleitend wird im Vortrag das Aktivitätsfeld Elektrische Energiespeicher und -umwandlung vorgestellt sowie eine kurze Einführung in die Terminologie der elektrischen Energiespeicher gegeben. Im Folgenden wird das BMBF-Vorhaben SEE-2L vorgestellt. Hier wird der Schwerpunkt auf die Entwicklung und den Aufbau eines Großversuchsstand für das thermische Durchgehen von Lithium-Batterien auf Modul- und Batterieebene gelegt. Darüber hinaus werden die Ergebnisse einer ersten Versuchsserie vorgestellt. Zum Abschluss wird ein kurzer Ausblick zu weiteren anstehenden Versuchen gegeben.
Second Life Verwendungen - Untersuchungen und erste Erfahrungen mit einem Ausbildungsdemonstrator
(2024)
Der Vortrag gibt zunächst einen Themeneinstieg in den Bereich der Second-Life-Batterien sowie rechtliche und technische Grundlagen zu Lebenszyklus und Alterung. Im Weiteren werden experimentelle Ergebnisse aus Versuchen zum thermischen Durchgehen mit Batteriemodulen aus dem BMBF-Vorhaben SEE-2L vorgestellt. Darüber hinaus wird ein eigens entwickelter Ausbildungsdemonstrators vorgestellt, welcher einen wesentlichen Baustein des Ergebnistransfers aus dem Vorhaben darstellt.
The consideration of ageing mechanisms is with integration into the IAEA-requirements now obligatory for the design of transport packages. For packages intended to be used for shipment after storage the consideration of the effects of ageing mechanisms during storage in safety analyses and the implementation of corresponding instructions for operation and maintenance are required. Therefore, these packages have been maintained during storage in a manner that all requirements specified in the IAEA-requirements and in the applicable certificates of approval have been fulfilled.
BAM is the competent authority in Germany for evaluating the thermal and mechanical design of packages for the transport of radioactive materials. In this context, BAM also evaluates the aging mechanisms and aging effects occurring during the long-term storage period of such transport packages. BAM has developed a guideline for the implementation of ageing assessment and of the measures for ageing management into the approval procedure based on IAEA-requirements.
The goal of the presented paper is to introduce this guideline and the general approach for ageing management requirements and to describe the application to a specific package design. The type and amount of the ageing management not only depend on the use of the packaging, but also on the accessibility of the components that are considered in the ageing assessment. The different operating phases of a packaging are considered for the ageing assessment, such as loading, interim storage or transport.
The implementation of measures for ageing management is divided into three levels – systemic measures, package design related measures and documentation. The systemic measures are attributed to the general management system and define the whole activities for organization of ageing management like structure, responsibilities, documentation, reports and evaluation. The package design related measures are defined in an ageing management plan. These measures shall ensure that the anticipated changes of the package design under consideration of ageing effects still complies with the design approval specification. Therefore, an ageing surveillance program and, if necessary, a gap analysis program shall be developed. The ageing management documentation ensures the continuous documentation of the compliance of a specific package to the approved package design, comprising mainly records resulting from operation and surveillance.
Die Integration und Wiederverwendung von Wissen und Daten aus der Herstellung, Bearbeitung und Charakterisierung von Materialien wird im Zuge der digitalen Transformation in der Materialwissenschaft und Werkstofftechnologie in verschiedenen Projekten behandelt. Dabei liegt der Fokus auf der Interoperabilität von Daten und Anwendungen, die nach den FAIR-Prinzipien erstellt und veröffentlicht werden. Zur Umsetzung eines komplexen Datenmanagements und der Digitalisierung im Bereich der Materialwissenschaften gewinnen Ontologien zunehmend an Bedeutung. Sie ermöglichen sowohl menschenlesbare als auch maschinenverständliche und -interpretierbare Wissensrepräsentationen durch semantische Konzeptualisierungen.
Im Rahmen des Projektes Plattform MaterialDigital (PMD, materialdigital.de), welches in dieser Präsentation vorgestellt wird, werden Ontologien verschiedener Ebenen entwickelt (verbindende mid-level sowie Domänen-Ontologien). Die PMD-Kernontologie (PMD Core Ontology - PMDco) ist eine Ontologie der mittleren Ebene, die Verbindungen zwischen spezifischeren MSE-Anwendungsontologien und domänenneutralen Konzepten herstellt, die in bereits etablierten Ontologien höherer Ebenen (top-level Ontology) verwendet werden. Sie stellt somit einen umfassenden Satz von durch Konsensbildung in der Gemeinschaft (geteiltes Vokabular) entstanden Bausteinen grundlegender Konzepte aus der Materialwissenschaft und Werkstofftechnik (MSE) dar. In dieser Präsentation wird die PMDco adressiert.
Weiterhin wird eine auf die PMDco bezogene normenkonforme ontologische Repräsentation zur Speicherung und Weiterverarbeitung von Zugversuchsdaten – die Tensile Test Ontology (TTO) – präsentiert, die in enger Zusammenarbeit mit dem zugehörigen DIN-Standardisierungsgremium NA 062-01-42 AA erstellt wurde. Dies umfasst den Weg von der Entwicklung einer Ontologie nach Norm, der Konvertierung von Daten aus Standardtests in das interoperable RDF-Format bis hin zur Verbindung von Ontologie und Daten. Auf Grundlage der dabei entwickelten Struktur und Vorgehensweise können weitere Materialcharakterisierungsmethoden semantisch beschrieben werden, woraus sich in diesem Zusammenhang Kooperationsmöglichkeiten ergeben.
Morphological and chemical analysis of mesoporous mixed IrOx-TiOy thin films as electrode materials
(2024)
Porous films play an important role particularly in energy applications like photovoltaics, electrolysis or batteries. Thin film properties such as thickness, chemical composition, crystallinity of the framework, and porosity define the activity of the porous films. The accurate morpho-chemical characterisation of mesoporous thin films is a challenging analytical task which requires the consideration of new analytical approaches based on the combination of data of different methods able to address the structure and chemical composition at the nanoscale. In this contribution we characterise thin mesoporous iridium-titanium mixed oxide film properties by Electron Probe Microanalysis (EPMA) with Energy-Dispersive X-ray Spectroscopy (EDS) at an SEM applied in a dedicated “thin film analysis” approach (1). Thus, the film mass deposition, film thickness and the film density can be determined. Further, by dividing the measured film density to an assumed (theoretical) metal oxide framework (skeletal) density, the thin film porosity can be extracted, too.
In order to assess the homogeneity of the thin film properties like the chemical composition, Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and Auger Electron Spectrometry are applied in the depth profiling mode, so that possible in-depth gradients are detected. Lateral inhomogeneities in the chemical composition and structure of the thin mesoporous films are also identified by applying the same methods in the line-scan or mapping mode, which can be further combined with in-depth sputtering for 3D information. The role of the spatial resolution of the analytical methods considered, which can go down well below 100 nm, will be highlighted.
Traceable morphological and chemical characterization of nanomaterials with respect to the various possible sizes, size distributions, shapes, and concentrations of real-world nanoparticles (NPs) is a challenging task. Particularly for the nonspherical, non-monodisperse nanoparticles – as typically for most of the commercial particles, including their strong tendency to agglomerate, there is a lack of standard operation procedures providing accurate nanoparticle characterisation.
In the framework of the pre-standardisation framework of VAMAS (Versailles Project on Advanced Materials and Standards, www.vamas.org) two interlaboratory comparison (ILC) studies are being carried out under the Technical Working Area (TWA) 34 “Nanoparticle Populations”:i) Project #15 addresses the analysis of the size and shape distribution of TiO2 bipyramidal NPs by traceable imaging methods such as TEM, SEM, STEM-in-SEM, AFM as well as with SAXS as an ensemble method. This ILC is thought as the next level development of the case studies exemplified in the published ISO standards ISO 21363 and ISO 19749. It was agreed to complete the first ILC with the NPs already prepared according to the same procedure on a TEM grid, and, at a later stage, to carry out second ILCs with the same NPs distributed to the participants as liquid suspensions together with protocols for the uniform NP deposition on suited substrates - as developed and optimized within the European project nPSize. Once having good deposition protocols available, the door for automated image analysis gets opened. Corresponding image analysis protocols and reporting templates have been distributed to the ILC participants, too.
ii) Project #16: two spherical SiO2 NP samples with bi-modal size distributions in two nominal relative number concentrations were prepared and distributed also as liquid suspensions accompanied by sample preparation, measurement, and image analysis protocols and reporting templates. Here, the NP concentration is the primary parameter to be measured. For the imaging methods it is targeted to
measure the relative nanoparticle concentrations (relative populations of the two modes).
The results of all the participating laboratories, in both ILCs, compiled in comparative representations will be shown and discussed for the first time. The reduction of the measurement uncertainties associated to the size, shape and number-concentration results induced by the significant improvement of the sample preparation on substrates (as single particles with a high-density coverage), combined with welldefined image analysis procedures will be highlighted.
Advancements in bulk metallic glass thermoplastic forming unleash the potential to fabricate microscale metallic features with unparalleled precision and durability, i.e. microspine gripping structures for mobility platforms on planetary or in-space robots. Four designs of grippers were fabricated and rigorously tested. Coefficient of friction on four test surfaces were measured and compared to SiC paper and Velcro. The hardness and elasticity of the bulk metallic glasses make them a game-changer in the field, offering a superior alternative to conventional nonmetallic grippers.
An interlaboratory study, involving eigth international laboratories and coordinated by COMTES FHT (Czech Republic), was conducted to validate tensile measurements obtained using miniature specimens on additively manufactured (AM) components and artifacts. In addition to AM 316L stainless steel (316L SS), a wrought highstrength steel (34CrNiMo6V, equivalent to AISI 4340) was also used. Based on the results, a precision statement in accordance with ASTM E691 standard practice was developed, intended for inclusion in a proposed annex to the ASTM E8/E8M tension testing method. The primary outcomes of the study highlighted the agreement between yield and tensile strength measured from miniature and standard-sized tensile specimens. Furthermore, most tensile properties exhibited similar standard deviations, offering users insight into the efficacy of miniature specimen applications.
The consideration of ageing mechanisms is with integration into the IAEA-requirements now obligatory for the design of transport packages. For packages intended to be used for shipment after storage the consideration of the effects of ageing mechanisms during storage in safety analyses and the implementation of corresponding instructions for operation and maintenance are required. Therefore, these packages have been maintained during storage in a manner that all requirements specified in the IAEA-requirements and in the applicable certificates of approval have been fulfilled.
BAM is the competent authority in Germany for evaluating the thermal and mechanical design of packages for the transport of radioactive materials. In this context, BAM also evaluates the aging mechanisms and aging effects occurring during the long-term storage period of such transport packages. BAM has developed a guideline for the implementation of ageing assessment and of the measures for ageing management into the approval procedure based on IAEA-requirements.
The goal of the presented paper is to introduce this guideline and the general approach for ageing management requirements and to describe the application to a specific package design. The type and amount of the ageing management not only depend on the use of the packaging, but also on the accessibility of the components that are considered in the ageing assessment. The different operating phases of a packaging are considered for the ageing assessment, such as loading, interim storage or transport.
The implementation of measures for ageing management is divided into three levels – systemic measures, package design related measures and documentation. The systemic measures are attributed to the general management system and define the whole activities for organization of ageing management like structure, responsibilities, documentation, reports and evaluation. The package design related measures are defined in an ageing management plan. These measures shall ensure that the anticipated changes of the package design under consideration of ageing effects still complies with the design approval specification. Therefore, an ageing surveillance program and, if necessary, a gap analysis program shall be developed. The ageing management documentation ensures the continuous documentation of the compliance of a specific package to the approved package design, comprising mainly records resulting from operation and surveillance.
We introduce a passive smart dust concept as a novel solution for environmental monitoring. Utilizing chemical reagents like colorimetric indicators and other chemosensors, these particles detect varying environmental conditions. We developed paper-based sensors that are both cost-effective and eco-friendly. In practical tests, these sensors, dispersed over a designated area, successfully identified hazardous substances by changing their color when exposed to acids or bases. This color change was remotely detectable using a drone-mounted color camera. The data thus obtained was processed through specialized software, accurately pinpointing areas of contamination. This method proves the efficacy and scalability of passive smart dust technology for real-time, environmentally sustainable remote sensing of hazardous materials
Use/distribution of cost-effective and biocompatible pieces of cellulose paper as passive optical chemosensors and readout by the camera system.
Modification of the paper surface using various chemically sensitive dyes (indicators) provides an optically detectable reaction and conclusions about the target substances and precise location.
In infrared thermography, the interaction of the heat flow with the internal geometry or inhomogeneities in a sample and their effect on the transient temperature distribution is used, e.g., to detect defects non-destructively. An equivalent way of describing this is the propagation of thermal waves inside the sample. Although thermography is suitable for a wide range of inhomogeneities and materials, the fundamental limitation is the diffuse nature of thermal waves and the need to measure their effect radiometrically at the sample surface only. The crucial difference between diffuse thermal waves and propagating waves, as they occur, e.g., in ultrasound, is the rapid degradation of spatial resolution with increasing defect depth. This degradation usually limits the applicability of thermography for finding small defects on and below the surface.
A promising approach to improve the spatial resolution and thus the detection sensitivity and reconstruction quality of the thermographic technique lies in the shaping of these diffuse thermal wave fields using structured laser thermography.
Some examples are:
• Narrow crack-like defects below the surface can be detected with high sensitivity by superimposing several interfering thermal wave fields,
• Defects very close to each other can be separated by multiple measurements with varying heating structures,
• Defects at different depths can be distinguished by an optimized temporal shaping of the thermal excitation function,
• Narrow cracks on the surface can be found by robotic scanning with focused laser spots.
We present the latest results of this technology obtained with high-power laser systems and modern numerical methods.
Thermographic NDT is based on the interaction of thermal waves with inhomogeneities. The propagation of thermal waves from the heat source to the inhomogeneity and to the detection surface according to the thermal diffusion equation leads to the fact that two closely spaced defects can be incorrectly detected as one defect in the measured thermogram. In order to break this spatial resolution limit (super resolution), the combination of spatially structured heating and numerical methods of compressed sensing can be used.
The improvement of the spatial resolution for defect detection then depends in the classical sense directly on the number of measurements. Current practical implementations of this super resolution detection still suffer from long measurement times, since not only the achievable resolution depends on performing multiple measurements, but due to the use of single spot laser sources or laser arrays with low pixel count, also the scanning process itself is quite slow. With the application of most recent high-power digital micromirror device (DMD) based laser projector technology this issue can now be overcome.
Our studies deal with the application of fully 2D-structured DMD-based excitation and subsequent super-resolution-based defect reconstruction. We analyze the influence of different testing parameters, like the number of measurements or the white content of the excitation pattern. Furthermore, we have dealt with the choice of parameters in the reconstruction that have an influence on the underlying minimization problem in terms of compressed sensing. Finally, the results of the super resolution reconstruction are compared with the results based on conventional thermographic testing methods.
Die zunehmende Bedeutung der luftgekoppelten Ultraschallprüfung (ACUT) in der zerstörungsfreien Prüfung (ZfP) unterstreicht die Notwendigkeit von standardisierten Abläufen und Methoden. Bei der ACUT bestehen grundlegende Unterschiede zur manuell durchgeführten Ultraschallprüfung mit Kontakttechnik oder zur automatisierten Tauchtechnik. Die Unterschiede bei der Bestimmung von Prüfkopfparametern für ACUT wurde von Herstellern, Forschungseinrichtungen und Anwendern bereits als wichtig erkannt, was sie veranlasst hat, im Rahmen des Unterausschusses Luftgekoppelte Ultraschallprüfung der DGZfP die Richtlinie US08 zur standardisierten Charakterisierung von luftgekoppelten Ultraschallwandlern zu erarbeiten. Darüber hinaus bestehen auch bei der Durchführung einer Messung grundlegende Unterschiede, die aktuell in einem Leitfaden zusammengetragen und definiert werden.
In diesem Beitrag wird ein Überblick über die geplanten Inhalte dieses Leitfadens gegeben. Insbesondere wird die Auswahl von Prüfparametern in Form von Frequenzen, Abständen und Positionierung sowie die Auswertung behandelt. Darüber hinaus werden die Ergebnisse eines Ringversuchs vorgestellt, welcher an einem eigens hierfür entwickelten und mit Defekten versehenem Prüfkörper, der sog. ACUT-Prüfplatte, durchgeführt wurde. In diesem Ringversuch werden unterschiedliche Messanordnungen, die mittels luftgekoppeltem Ultraschall möglich sind, anhand des erreichbaren Signal-Rausch-Verhältnisses sowie der messbaren Defektgröße quantifiziert. Zudem findet eine Abgrenzung zu weiteren gängigen Verfahren der ZfP statt. Anhand der hier vorgestellten Ergebnisse ist es möglich, die Anwendbarkeit des luftgekoppelten Ultraschalls unter Berücksichtigung unterschiedlicher Messanordnungen besser einzuschätzen.
Die größten Vorteile der luftgekoppelten Ultraschallprüfung sind: die berührungslose Prüfung und der Verzicht auf ein flüssiges Koppelmittel. Allerdings weisen die meisten luftgekoppelten Prüfszenarien ein sehr geringes Signal-zu-Rausch-Verhältnis (SNR) auf und die Pegel, die von luftgekoppelten Ultraschallwandlern realisiert werden, sind um mehrere Größenordnungen kleiner.
Da diese Herausforderung auch in anderen Disziplinen wie bspw. der Radartechnik existiert und dort ebenfalls eine entscheidende Rolle spielt, wurde die dort eingesetzte Pulskompression auf die physikalischen Gegebenheiten der luftgekoppelten Ultraschallprüfung angepasst und angewandt.
Dieser Beitrag präsentiert die Ergebnisse von zwei Versuchsaufbauten: 1) ein thermoakustischer Sender und ein optisches Mikrofon und 2) ein Paar Ferroelektret-Wandler als Sender und Empfänger. Aufgrund der physikalischen Randbedingungen wurden unipolare Kodierungen verwendet. Die Verwendung von unipolaren Kodes zur Modulation der Anregungssignale stellt dabei eine neue Methode dar, die so die Pulskompression für Ferroelektret- und thermoakustische Wandler ermöglichen soll. Die Anwendung der Pulskompression auf die Kombination aus thermoakustischem Sender und optischem Mikrofon konnte das Signal-zu-Rausch-Verhältnis um bis zu 15 dB und für die Ferroelektret-Wandler um bis zu 23 dB erhöhen.
Die größten Vorteile der luftgekoppelten Ultraschallprüfung sind: die berührungslose Prüfung und der Verzicht auf ein flüssiges Koppelmittel. Allerdings weisen die meisten luftgekoppelten Prüfszenarien ein sehr geringes Signal-zu-Rausch-Verhältnis (SNR) auf und die Pegel, die von luftgekoppelten Ultraschallwandlern realisiert werden, sind um mehrere Größenordnungen kleiner.
Da diese Herausforderung auch in anderen Disziplinen wie bspw. der Radartechnik existiert und dort ebenfalls eine entscheidende Rolle spielt, wurde die dort eingesetzte Pulskompression auf die physikalischen Gegebenheiten der luftgekoppelten Ultraschallprüfung angepasst und angewandt.
Dieser Beitrag präsentiert die Ergebnisse von zwei Versuchsaufbauten: 1) ein thermoakustischer Sender und ein optisches Mikrofon und 2) ein Paar Ferroelektret-Wandler als Sender und Empfänger. Aufgrund der physikalischen Randbedingungen wurden unipolare Kodierungen verwendet. Die Verwendung von unipolaren Kodes zur Modulation der Anregungssignale stellt dabei eine neue Methode dar, die so die Pulskompression für Ferroelektret- und thermoakustische Wandler ermöglichen soll. Die Anwendung der Pulskompression auf die Kombination aus thermoakustischem Sender und optischem Mikrofon konnte das Signal-zu-Rausch-Verhältnis um bis zu 15 dB und für die Ferroelektret-Wandler um bis zu 23 dB erhöhen.
In this paper, we investigate the influence of different heat source pulse shapes by Infrared impulse thermography (IRT) on the results of the thermal shock response spectrum (TSRS) methodology. TSRS is a new alternative approach for evaluating impulse thermography (IRT) data based on an analogy to Shock Response Spectrum (SRS) analysis (ISO 18431) for mechanical systems. It allows processing the entire recorded signal without truncating the saturated thermogram, as in pulse-phase thermography (PPT) or thermal signal reconstruction (TSR). For this purpose, we use a widespread halogen lamp as heat source as well as laser spot. The laser source enables not only to generate a precise shape of the pulse, but also to heat a specific area of the sample uniformly. This makes it possible to suppress influences of lateral fluxes due to uneven distribution of the excitation source on the surface of the specimen and leads to improved results. In order to quantitatively compare the results and to investigate the possible influence of the source shape on the TSRS, the Tanimoto criterion and the signal-to-noise ratio (SNR) were applied to the region of interest (ROI) of the carbon fiber reinforced polymer (CFRP) laminate with artificial defects as defect detectability criterion.
In this study, we investigated the diverse range of materials used for sizing in Iranian paper manuscripts during the Timurid (fifteenth century) to Safavid (sixteenth century) and Qajar (nineteenth century) periods. Our approach combined historical analysis with scientific examination of reconstructed sizings. We reconstructed 15 sizing materials based on identified Persian historical recipes and analysed their physical, optical, and spectral characteristics. Additionally, we assessed their behaviour against the mould fungus Aspergillus flavus. The results revealed distinctive properties for each sizing material, shedding light on their potential applications in paper preservation. Furthermore, our investigation demonstrated variations in hygroscopicity, thickness, grammage, and ash content post-sizing. The sizing materials also exhibited different effects on paper reflectance properties. Additionally, our study revealed insights into the impact of sizing on burnished papers, indicating that the mechanical process of burnishing did not significantly alter the chemical composition or spectral properties of the paper, with only minor changes in brightness observed in specific cases. All tested sizing materials supported varying levels of mould growth, indicating potential implications for paper conservation. Our findings provide valuable insights into the historical practices of Iranian paper sizing and offer practical considerations for the preservation of paper manuscripts.
Mikroplastik Detektion mit Thermoanalytischen Methoden: Analytik, Referenzmaterial, Ringversuche
(2024)
Ich dem Vortrag geht es um die Vorstellung von thermoanalytischen Methoden für die Mikroplastik-Detektion. Verschiedene Kopplungsmöglichkeiten werden gezeigt und die Funktionsweise der TED-GC/MS wird erklärt. Im zweiten Teil werden Referenzmaterialien für die Mikroplastik-Analytik diskutiert. PET -Tabletten des PlasticTrace Projektes werden vorgestellt. Am Ende wird der VAMAS Ringversuch zur Mikroplastik-Detektion gezeigt.
Die additive Fertigung von Metallen hat inzwischen einen Reifegrad erreicht, der einen Einsatz in vielen Industriezweigen ermöglicht oder in greifbare Nähe rückt. Die Vorteile liegen vor allem in der Möglichkeit der Fertigung komplexer Bauteile, die sich konventionell nicht oder nur sehr aufwändig produzieren lassen, sowie in der Fertigung von hochindividualisierten Bauteilen in kleinen Stückzahlen. Allerdings ist der additive Fertigungsprozess hoch komplex und fehleranfällig. Um eine insbesondere für sicherheitsrelevante Bauteile notwendige Qualitätskontrolle zu gewährleisten, ist aktuell aufwändige nachgelagerte ZfP der einzelnen Bauteile notwendig. Alternativen könnten die In-situ-Prozessüberwachung und -prüfung bieten, die aktuell aber noch keinen ausreichenden Entwicklungsstand erreicht haben. Industrielle Fertigungsanlagen bieten keine oder nur geringe Flexibilität und Zugänglichkeit, um umfangreiche Untersuchungen auf diesem Gebiet zu ermöglichen. Daher haben wir an der BAM ein System für den Prozess des selektiven Laserschmelzens (PBF-LB/M) entwickelt, genannt SAMMIE. Es bietet eine komplett offene Systemarchitektur mit voller Kontrolle über den Prozess und flexiblem Zugang zur Baukammer, z.B. optisch sowohl direkt als auch koaxial zum Fertigungslaser. In diesem Beitrag stellen wir das System vor und zeigen erste experimentelle Ergebnisse der In-situ-Überwachung und -prüfung: Thermografische Schmelzbadüberwachung, optische Tomografie und In-situ-Laserthermografie. SAMMIE ermöglicht uns grundlegende Untersuchungen, die helfen werden, die In-situ-Prozessüberwachung und -prüfung weiterzuentwickeln, neue Erkenntnisse über die additive Fertigung zu gewinnen und die Sicherheit und Zuverlässigkeit des Prozesses zu verbessern.
For a deep process understanding of the laser powder bed fusion process (PBF-LB/M), recording of the occurring surface temperatures is of utmost interest and would help to pave the way for reliable process monitoring and quality assurance. A notable number of approaches for in-process monitoring of the PBF-LB/M process focus on the monitoring of thermal process signatures. However, due to the elaborate calibration effort and the lack of knowledge about the occurring spectral directional emissivity, only a few approaches attempt to measure real temperatures. In this study, to gain initial insights into occurring in the PBF-LB/M process, measurements on PBF-LB/M specimens and metal powder specimens were performed for higher temperatures up to T = 1290 °C by means of the emissivity measurement apparatus (EMMA) of the Center for Applied Energy Research (CAE, Wuerzburg, Germany). Also, measurements at ambient temperatures were performed with a suitable measurement setup. Two different materials—stainless steel 316L and aluminum AlSi10Mg—were examined. The investigated wavelength λ ranges from the visible range (λ-VIS = 0.40–0.75 µm) up to the infrared, λ = 20 µm. The influence of the following factors were investigated: azimuth angle φ, specimen temperature TS, surface texture as for PBF-LB/M surfaces with different scan angles α, and powder surfaces with different layer thicknesses t.
Several investigation groups have studied the flame-retardancy modes of action and properties of epoxy resins in the past; nevertheless, the selection of suitable flame retardants for epoxy resins remains challenging, and the transfer to fiber composites is difficult. The addition of flame retardants and glass fibers (GFs) to a polymeric system in a fire scenario changes the polymer's pyrolytic path and burning characteristics, reduces the heat released in the combustion, and suppresses the modes of action in the condensed and gas phase. In this study, the thermal analysis, flammability, fire behavior, residue analysis, fire stability, and quantification of modes of action of three different systems with three halogen-free flame retardants (melamine polyphosphate (MPP), ammonium polyphosphate (APP), and silane ammonium polyphosphate (SiAPP)) and three different types of GFs (unidirectional (UD), bidirectional (BD), and woven roving (WR)) will be compared with pure epoxy resin as a reference.
Distributed fiber optic sensing (DFOS) technique is a promising and robust non-destructive testing tool that can seamlessly acquire environmental conditions over large scales. Therefore, it has found extensive applications in structural health monitoring. Its appeal for monitoring underground facilities lies in the intrinsic properties of the optical fiber, such as immunity to magnetic interference, small size, chemical inertia, etc. This paper provides a concise overview of DFOS applications in underground facility monitoring. Following a brief introduction to the working principle of the DFOS technique, various examples are provided to demonstrate how distributed fiber sensors contribute to monitoring underground facilities. The paper presents unpublished field test results with an emphasis in the energy sector, including monitoring gas storage facilities, geothermal reservoir exploration, and ground movement detection. Furthermore, the paper identifies several directions for enhancing the DFOS system.
Im Rahmen des BMBF-Vorhabens SEE-2L wurde auf dem Testgelände Technische Sicherheit (BAM TTS) ein Großversuchsstand für das thermische Durchgehen von Lithium-Batterien auf Modul- und Batterieebene entwickelt und aufgebaut. Im Zuge des Projektes konnte eine erste Versuchsserie zu den Auswirkungen des thermischen Durchgehens von Batteriemodulen durchgeführt werden. Im Vortrag werden die wesentlichen Ergebnisse der Versuche vorgestellt.
Im Rahmen des Forschungsprojekts "Artificial Intelligence for Rail Inspection" (AIFRI) wird ein KI-Algorithmus entwickelt, um die Fehlererkennung und Bewertung bei der Auswertung von Schienenprüfungen mittels Ultraschall- und Wirbelstromprüfverfahren zu verbessern. Die Bandbreite möglicher Defekte und die Menge an Einflussgrößen auf die Schienenprüfung ist sehr groß, aber die Prüfdaten aus dem Feld bilden diese Bandbreite nicht balanciert ab und sind unzureichend gelabelt. Durch Simulationen werden große Mengen detailliert gelabelter Daten für relevante Schienenschädigungen und Artefakte bereitgestellt. Aus diesen Daten werden wiederum virtuellen Prüffahrten erstellt, die für das Training und die Validierung der KI genutzt werden können.
In unserem Vortrag stellen wir den Erstellungsprozess der Datensätze vor. Jeder Schritt von der Geometriedarstellung bis zur Datenverarbeitung wird erfasst. Der Fokus wird auf Simulationsergebnisse und deren Verarbeitung gelegt. Die Signalverarbeitung spielt in den Datensätzen eine große Rolle, dabei werden die Datensätze an die realen Daten angepasst. Für Wirbelstrom und Ultraschall werden diese Prozesse im Hinblick auf die Fehlertypen Head Checks und Bohrungsanrisse veranschaulicht. Ferner diskutieren wir die Simulation von Schweißnähten, die von beiden Prüfsystem detektiert werden können; und somit besondere Abstimmung bedürfen aber auch Synergieeffekte zwischen den Prüfsystem ermöglichen.
Für die Ablage der Datensätze verweisen wir auf das ebenfalls eingereichte Poster „Verwendung von DICONDE bei der Eisenbahn-Schienenprüfung“.
Das Projekt AIFRI wird im Rahmen der Innovationsinitiative mFUND unter dem Förderkennzeichen 19FS2014 durch das Bundesministerium für Digitales und Verkehr gefördert.
Revolutionizing our polymer industry for adaption to a sustainable carbon circular economy has become one of today’s most demanding challenges. Exploiting renewable resources to replace fossil-fuel—based plastics with biopolymers such as poly(lactic acid) (PLA) is inevitable while using waste streams as a raw material resource at least is promising. When it comes to using PLA as technical polymer, its high flammability must be addressed by flame retardants compatible with the thermoplastic processing of PLA and its compostability. This study proposes microalgae enriched with phosphorus from wastewater (P-Algae) as an elegant way towards a kind of sustainable organophosphorus flame retardant. The concept is demonstrated by investigating the processing, pyrolysis, flammability, and fire behavior of PLA/P-Algae, while varying the P-Algae content and comparing P-Algae with four alternative bio-fillers (phosphorylated lignin, biochar, thermally treated sewage sludge, and metal phytate) with different P-contents as meaningful benchmarks.
The production of formaldehyde on industrial scale requires huge amounts of energy due to the involvement of reforming processes in combination with the demand in the megaton scale. Hence, a direct route for the transformation of (bio)methane to formaldehyde would decrease costs and puts less pressure on the environment. Herein, we report on the use of zinc modified silicas as possible support materials for vanadium catalysts and the resulting consequences for the performance in the selective oxidation of methane to formaldehyde. After optimization of the Zn content and reaction conditions, a remarkably high space-time yield of 12.4 kgCH2O⋅kgcat − 1 ⋅h− 1 was achieved. As a result of the extensive characterization by means of UV–vis, Raman, XANES and NMR spectroscopy it was found that vanadium is in the vicinity of highly dispersed zinc atoms which promote the formation of active vanadium species as supposed by theoretical calculations. This work presents a further step of catalyst development towards direct industrial methane conversion which may help to overcome current limitations in the future.
This presentation gives an overview of the recent achievements in simulating piping erosion during the installation process of suction bucket foundations for offshore wind turbines. The physical correctness of the code is validated, and the simulation code's performance on the LUMI supercomputer is presented. The simulation results are compared to experimental data.
Low Transformation Temperature (LTT)-Schweißzusätze stellen einen innovativen Ansatz zur Erhöhung der Ermüdungsfestigkeit geschweißter Konstruktionen dar. LTT-Schweißzusätze zeichnen sich durch eine martensitische Phasenumwandlung nahe der Raumtemperatur aus, welche Druckeigenspannungen in der Schweißnaht und der Wärmeeinflusszone (WEZ) generieren.
Dieser Vortrag fokussiert sich auf die gezielte Einbringung zusätzlicher LTT-Lagen an ermüdungskritischen Stellen von konventionell geschweißten Verbindungen. Dies ermöglicht eine ökonomische Anwendung, ohne dass die Schweißnahtintegrität zu stark beeinflusst wird. Die Auswirkungen zusätzlicher LTT-Lagen wurden anhand geschweißter Längssteifen aus hochfestem Stahl hinsichtlich der chemischen Zusammensetzung und der Eigenspannungen untersucht. Unter Variation der Schweißgeschwindigkeit und Abstand zur konventionellen Naht konnten 3 unterschiedliche Nahtausführungen des Chrom-Nickellegierten LTT-Zusatzes bewertet werden.
Die chemische Zusammensetzung wurde mittels OES-Analysen untersucht. Dabei stellte heraus, dass die Aufmischung in allen Varianten sehr ähnlich war trotz teils unterschiedlicher LTT-Volumina. Härtebestimmungen ergaben in allen 3 Varianten eine ähnliche Härte. Daraus lässt sich annehmen, dass die Martensitstarttemperatur bei allen Nahtvarianten ähnlich ist.
Röntgenografische Eigenspannungsmessungen belegen, dass die Eigenspannungen am versa-genskritischen Nahtübergang bei Einsatz von LTT-Schweißzusätzen deutlich abgesenkt werden. Während die konventionelle Schweißnaht Zugeigenspannungen von ca. 350 MPa aufweist, können an den LTT-Nähten teilweise Druckeigenspannungen von bis zu -150 MPa nachgewiesen werden. Je höher der Abstand zur konventionellen Naht und je größer das eingebrachte LTT-Volumen ist, umso stärker sind die Eigenspannungsreduzierungen am Nahtübergang. Da in allen 3 Varianten eine ähnliche Martensitstarttemperatur angenommen werden kann, ist somit die Geometrische Komponente der LTT-Zusatzlage ein entscheidender Faktor für die Eigenspannungsreduzierung.
In 2007 the license for the German Konrad repository for low and intermediate level radioactive waste was finally confirmed. Since then, the site is improved, prepared and equipped for the currently planned start of waste package emplacement in 2029. Bundesanstalt fuer Materialforschung und -pruefung is regularly contracted by the Bundesgesellschaft für Endlagerung as the responsible authority for waste product control, waste container design testing, and waste package acceptance. In this context BAM is mainly responsible for design testing of various container types including the evaluation of quality assurance measures for container manufacturing.
In addition to general requirements concerning container design, the casks have to withstand specific mechanical load scenarios. Drop tests from different heights under consideration of the most damaging drop orientation and a stacking test are two examples for necessary safety demonstrations.
If the containers are made from concrete the reinforcement has the function to absorb tensile forces the concrete is not able to withstand by its own. Because of manufacturing imperfections of cylindrical concrete containers manufactured already decades ago, the reinforcement cages are not always exactly, asymmetrically positioned when they were poured. This inspired BAM to perform various ABAQUS® finite-element (FE) simulations by using the example of a simplified cylindrical container design with generic dimensions. On the basis of the calculated tensile and compressive stress distributions suggestions are derived on how a cylindrical concrete container with an imperfectly placed reinforcement cage has to be oriented for a drop or stacking test to ensure the most damaging test scenario.
Dem AVK-Arbeitskreis Wasserstoff-Drucktanks werden ausgehend von Zielen und Aufgaben der BAM sowie der Fachkompetenz auf dem Gebiet der Sicherheit von Composite-Druckbehältern über die prüftechnische Ausstattung, die angewendeten und weiterentwickelten Prüf- und Untersuchungsmethoden sowie zu Beispielen von Forschungsvorhaben wie DELFIN, COLIBRI und SH2APED berichtet.
This paper explores combining a gimbal-mounted tunable diode laser absorption spectroscopy (TDLAS) sensor and a video camera to create a virtual gas camera for methane leak detection. This provides a low-to-zero-cost extension of typical TDLAS gas tomography systems. A prototype setup mounted on a ground robot is evaluated. Results acquired using a simulated methane leak show the feasibility of the virtual gas camera, accurately detecting methane leaks by overlaying concentrations onto a visual image. While the acquisition time is significantly longer than for traditional gas cameras, potential enhancements are discussed. The study concludes that the virtual gas camera is feasible and useful, despite its longer acquisition time. It serves as a valuable software-only addition to typical TDLAS gas tomography systems, offering quickly-available on-site data augmentation for visual leak assessment at low-to-zero cost.
This paper outlines significant advancements in our previously developed aerial gas tomography system, now optimized to reconstruct 2D tomographic slices of gas plumes with enhanced precision in outdoor environments. The core of our system is an aerial robot equipped with a custom-built 3-axis aerial gimbal, a Tunable Diode Laser Absorption Spectroscopy (TDLAS) sensor for CH4 measurements, a laser rangefinder, and a wide-angle camera, combined with a state-of-the-art gas tomography algorithm. In real-world experiments, we sent the aerial robot along gate-shaped flight patterns over a semi-controlled environment with a static-like gas plume, providing a welldefined ground truth for system evaluation. The reconstructed cross-sectional 2D images closely matched the known ground truth concentration, confirming the system’s high accuracy and reliability. The demonstrated system’s capabilities open doors for potential applications in environmental monitoring and industrial safety, though further testing is planned to ascertain the system’s operational boundaries fully.
Understanding Stimulation of Conjugal Gene Transfer by Nonantibiotic Compounds: How Far Are We?
(2024)
A myriad of nonantibiotic compounds is released into the environment, some of which may contribute to the dissemination of antimicrobial resistance by stimulating conjugation. Here, we analyzed a collection of studies to (i) identify patterns of transfer stimulation across groups and concentrations of chemicals, (ii) evaluate the strength of evidence for the proposed mechanisms behind conjugal stimulation, and (iii) examine the plausibility of alternative mechanisms. We show that stimulatory nonantibiotic compounds act at concentrations from 1/1000 to 1/10 of the minimal inhibitory concentration for the donor strain but that stimulation is always modest (less than 8-fold). The main proposed mechanisms for stimulation via the reactive oxygen species/SOS cascade and/or an increase in cell membrane permeability are not unequivocally supported by the literature. However, we identify the reactive oxygen species/SOS cascade as the most likely mechanism. This remains to be confirmed by firm molecular evidence. Such evidence and more standardized and high-throughput conjugation assays are needed to create technologies and solutions to limit the stimulation of conjugal gene transfer and contribute to mitigating global antibiotic resistance.
Gas Distribution Mapping (GDM) is essential in monitoring hazardous environments, where uneven sampling and spatial sparsity of data present significant challenges. Traditional methods for GDM often fall short in accuracy and expressiveness. Modern learning-based approaches employing Convolutional Neural Networks (CNNs) require regular-sized input data, limiting their adaptability to irregular and sparse datasets typically encountered in GDM. This study addresses these shortcomings by showcasing Graph Neural Networks (GNNs) for learningbased GDM on irregular and spatially sparse sensor data. Our Radius-Based, Bi-Directionally connected GNN (RABI-GNN) was trained on a synthetic gas distribution dataset on which it outperforms our previous CNN-based model while overcoming its constraints. We demonstrate the flexibility of RABI-GNN by applying it to real-world data obtained in an industrial steel factory, highlighting promising opportunities for more accurate GDM models.
Packages for the transport of radioactive material are designed to en-dure severe accidents. Packages for the transportation of radioactive material must demonstrate that the package can withstand certain prescribed tests from the IAEA Regulations [1]. In addition to mechanical tests, a thermal test in form of a fire test must be carried out. As packages to be tested at BAM are signifi-cantly larger than previous package designs, BAM has expanded an existing fire test stand. A modular concept is chosen, which means that the arrangement of the burner nozzles can be adapted to the test specimen. The dimensions of the burner rings, the type, the orientation and the number of burner nozzles can be varied depending on the test specimen. In addition, various pumps can be used to set the corresponding mass flow. With the help of a calorimeter test, the fire test stand can be qualified for a specific size of packages regarding the boundary conditions of the IAEA Regulations [1]. Due to the typically wood filled impact limiters in German package designs, a fire test is necessary, as experiments have shown that possible openings that occurred during a mechanical test contributed to the igni-tion of the wood filled impact limiters within the prescribed 30 minutes of the IAEA Regulations [1]. From a series of experiments, two experiments are pre-sented to show the possibilities to obtain different temperatures and temperature rates in the test specimen. In addition to sensor data, the heat flux into the package is calculated to verify that the IAEA boundary conditions are satisfied. In addition to the temperature data, other data such as wind speed and wind direction are also recorded to explain subsequent effects in the measurement data in a comprehen-sible manner.
An Trinkwasserrohren aus ferritischem Stahl (1.4521) sind bei einigen größeren Bauvorhaben massive Korrosionsschäden aufgetreten. Die Leckagen treten ausschließlich durch Spaltkorrosion in Pressverbindungen auf, wo konstruktionsbedingt ein mit Wasser gefüllter Spalt zwischen der Rohr-Außenseite und dem Pressfitting gebildet wird. Im Vortrag werden die gewonnenen Erkenntnisse aus verschiedenen Schadensfällen der jüngeren Vergangenheit vorgestellt.
Acceptable limits for activity release from transport casks for high-level radioactive material specified in the IAEA regulations must be kept by the integrity of cask body and the cask sealing system. BAM as the German competent authority for mechanical, thermal and containment assessment of packages liable for approval verifies the activity release compliance with the regulatory limits. The specification of conservative package design leakage rates is one of the most important aspects in assessment.
Metal seals of the Helicoflex® Type are usually used to ensure the required package tightness for both, storage, and transport of the cask before and after storage. Due to the long-term use the seal behavior is influenced by temperature and time. The mechanical and thermal loadings associated with the routine, normal and accident conditions of transport specified in the regulations can have a significant effect on the leak tightness of the sealing system. Whereas the safety for application of new, non- aged Helicoflex® seals is verified sufficiently, there are still technical data gaps concerning the efficiency of aged Helicoflex® seals.
BAM performed experiments to learn more about the sealing efficiency of aged Helicoflex® seals with Aluminum and Silver outer jackets. The seals were compressed in test-flanges and for artificial ageing the complete flange systems were stored in an oven for several month at a high temperature. After this ageing procedure the flanges were opened completely, the seals were moved a little to vary the contact area, and the flanges were compressed again. During the compression and decompression tests after the aging, load-deformation characteristics of the seals, and leakage rates were measured.
With these tests a load situation was simulated, which can occur in the regulatory drop test of the cask: Under high impact loads the bolted lid can lift a little for a short moment, allowing a little movement of the seal, so that the contact area can change before compressing again.
Details about test conditions and first results will be presented in the poster.
This paper explores combining a gimbal-mounted tunable diode laser absorption spectroscopy (TDLAS) sensor and a video camera to create a virtual gas camera for methane leak detection. This provides a low-to-zero-cost extension of typical TDLAS gas tomography systems. A prototype setup mounted on a ground robot is evaluated. Results acquired using a simulated methane leak show the feasibility of the virtual gas camera, accurately detecting methane leaks by overlaying concentrations onto a visual image. While the acquisition time is significantly longer than for traditional gas cameras, potential enhancements are discussed. The study concludes that the virtual gas camera is feasible and useful, despite its longer acquisition time. It serves as a valuable software-only addition to typical TDLAS gas tomography systems, offering quickly-available on-site data augmentation for visual leak assessment at low-to-zero cost.
This paper outlines significant advancements in our previously developed aerial gas tomography system, now optimized to reconstruct 2D tomographic slices of gas plumes with enhanced precision in outdoor environments. The core of our system is an aerial robot equipped with a custom-built 3-axis aerial gimbal, a Tunable Diode Laser Absorption Spectroscopy (TDLAS) sensor for CH4 measurements, a laser rangefinder, and a wide-angle camera, combined with a state-of-the-art gas tomography algorithm. In real-world experiments, we sent the aerial robot along gate-shaped flight patterns over a semi-controlled environment with a static-like gas plume, providing a welldefined ground truth for system evaluation. The reconstructed cross-sectional 2D images closely matched the known ground truth concentration, confirming the system’s high accuracy and reliability. The demonstrated system’s capabilities open doors for potential applications in environmental monitoring and industrial safety, though further testing is planned to ascertain the system’s operational boundaries fully.
Gas Distribution Mapping (GDM) is essential in monitoring hazardous environments, where uneven sampling and spatial sparsity of data present significant challenges. Traditional methods for GDM often fall short in accuracy and expressiveness. Modern learning-based approaches employing Convolutional
Neural Networks (CNNs) require regular-sized input data, limiting their adaptability to irregular and sparse datasets typically encountered in GDM. This study addresses these shortcomings by showcasing Graph Neural Networks (GNNs) for learningbased GDM on irregular and spatially sparse sensor data. Our Radius-Based, Bi-Directionally connected GNN (RABI-GNN) was trained on a synthetic gas distribution dataset on which it outperforms our previous CNN-based model while overcoming its constraints. We demonstrate the flexibility of RABI-GNN by applying it to real-world data obtained in an industrial steel factory, highlighting promising opportunities for more accurate GDM models.
Packages for the transport of radioactive material are designed to en-dure severe accidents. Packages for the transportation of radioactive material must demonstrate that the package can withstand certain prescribed tests from the IAEA Regulations [1]. In addition to mechanical tests, a thermal test in form of a fire test must be carried out. As packages to be tested at BAM are signifi-cantly larger than previous package designs, BAM has expanded an existing fire test stand. A modular concept is chosen, which means that the arrangement of the burner nozzles can be adapted to the test specimen. The dimensions of the burner rings, the type, the orientation and the number of burner nozzles can be varied depending on the test specimen. In addition, various pumps can be used to set the corresponding mass flow. With the help of a calorimeter test, the fire test stand can be qualified for a specific size of packages regarding the boundary conditions of the IAEA Regulations [1]. Due to the typically wood filled impact limiters in German package designs, a fire test is necessary, as experiments have shown that possible openings that occurred during a mechanical test contributed to the igni-tion of the wood filled impact limiters within the prescribed 30 minutes of the IAEA Regulations [1]. From a series of experiments, two experiments are pre-sented to show the possibilities to obtain different temperatures and temperature rates in the test specimen. In addition to sensor data, the heat flux into the package is calculated to verify that the IAEA boundary conditions are satisfied. In addition to the temperature data, other data such as wind speed and wind direction are also recorded to explain subsequent effects in the measurement data in a comprehen-sible manner.
Following the new paradigm of materials development, design, and optimization, digitalization is the main goal in materials sciences and engineering (MSE) which imposes a huge challenge. In this respect, the quality assurance of processes and output data as well as the interoperability between applications following FAIR principles are to be ensured. For storage, processing, and querying of data in contextualized form, Semantic Web technologies (SWT) are used since they allow for machine-actionable and human-readable knowledge representations needed for data management, retrieval, and (re)use.
The project ‘platform MaterialDigital’ (PMD) aims to bring together and support interested parties from both industrial and academic sectors in a sustainable manner in solving digitalization tasks and implementing digital solutions. Therefore, the establishment of a virtual material data space and the systematization of the handling of hierarchical, process-dependent material data are focused. Core points to be dealt with are the development of agreements on data structures and interfaces implemented in distinct software tools and to offer users specific support in their projects. Furthermore, the platform contributes to a standardized description of data processing methods in materials research. In this respect, selected MSE methods are semantically represented on a prototypical basis which are supposed to serve as best practice examples with respect to knowledge representation and the creation of knowledge graphs used for material data.
Accordingly, this poster presentation illustrates demonstrators developed and deployed within the PMD project. Semantically anchored using the mid-level PMD Core Ontology (PMDco), they address data transformation leading to a novel data management which is based on semantic integrated data. The PMD data acquisition pipeline (DAP), which is fueled by traditional, diverse data formats, and a pipeline applying an electronic laboratory notebook (ELN) as data source are displayed. Additionally, the efficient combination of diverse datasets originating from different sources is demonstrated by the representation of a use case dealing with the well-known Orowan relation.
This report contains detailed information on the preparation of the reference material as well as on homogeneity and stability investigations of the property of interest, the equivalent particle diameter, and on the analytical methods to determine the additional properties. The values for particle size distribution are based on the results from laser diffraction measurements of 3 different devices with at least 3 replicate measurements of 4 randomly chosen units of the reference material P206.
This contributions shows the first results of the ongoing interlaboratory comparisons under VAMAS/TWA 34 Nanoparticle populations related on the determination of pasrticle size distribution and relative concentration of nanoparticles and an example of an ILC running under VAMAS/TWA 41 Graphene and Related 2D Materials on the determination of the lateral diemsnions of graphene oxide flakes by Scanning Electron Microscopy. The link to related standardisation projects at ISO/TC Nanotechnologies are explained.
Advanced materials, such as nanomaterials, 2D materials, or thin films, play a crucial role in driving economic development and addressing major challenges in the coming years. These challenges include mitigating the impact of climate change, advancing lightweight engineering, enhancing catalysis, and improving medical applications.
To comprehend the performance of these materials and ensure their acceptance across various sectors as safe and sustainable for both humans and the environment, the availability of reference procedures, materials, and data is essential. One versatile tool for establishing such references and evaluating the proficiency of individual laboratories and their competencies is through (international) interlaboratory comparisons (ILC). Notably, initiatives like the Versailles Project on Advanced Materials and Standards (VAMAS) provide a platform for conducting ILCs.
This webinar will showcase various examples of interlaboratory comparisons, illustrating their impact on the development of reference products.
The presentation provides an overview of the current European initiatives to introduce the Digital Product Passport (DPP). Starting from the political background, reference is made to the implementation in various European directives. According to current considerations, explosives and pyrotechnics are not excluded from this. The introduction of the DPP system requires the development of a solid basis of relevant standards, which are now being developed. The aim of BAM's efforts will be to digitally align the classification processes with a view to these developments.
Germany had been transporting spent fuel to the reprocessing plant in Sellafield and La Hague for decades until around 2005. Resulting from the obligation to take back the vitrified high-level waste from reprocessing six CASTOR® HAW28M filled with 168 canisters with radioactive waste in vitrified form were transported from Sellafield to the interim storage facility Biblis in 2020. Rail wagons were used for the transport to the port in Barrow-in-Furness, where they were loaded into a dedicated seagoing vessel, certified as INF Class 3 according to the INF Code. This was the first time that vitrified high level waste with considerable heat load was transported under a German design approval certificate.
BAM was involved in the authority assessment of the conditions for the sea transport. For the first transport BAM required among others, assessment of temperature distribution during transport, logging of temperatures of cargo bays and graphical imaging of temperatures of the bay with the cask in order to ensure compliance with temperature specifications, e.g. maximal neutron absorber and gasket temperatures. Special interest was taken in the identification of possible events exceeding the specified temperatures considering the different philosophies of IMDG code and its supplement INF code regarding temperature control of hatches. Results show compliance with assumed conditions.
Electron Back Scatter Diffraction (EBSD) is a very versatile analytical technique allowing for the characterization of material structure. Historically, diffraction images (Kikuchi patterns) registered during EBSD analysis were solved using Hough/Radon transformation. The last decade brought several novel techniques of experimental pattern analysis, focusing entirely on image analysis routines such as pattern matching, or various variants of High-Resolution EBSD. However, all the above-mentioned techniques require prior knowledge of the material structure to perform orientation analysis. The recently presented algorithm employed in Crystallographic Analysis of Lattice Metric (CALM) software, effectively removes this limitation enabling a standard-less analytical approach in EBSD systems. At its core, the CALM technique couples accurate detection of the Kikuchi bands position, with a rigid construction of reciprocal lattice resulting from translational crystal symmetry. A unique characteristic of the methodology also gives an opportunity for application in the analysis of continuous lattice changes, for example tetragonality mapping. During mapping, however, the geometry of the gnomonic projection (represented by the projection center) is continuously altered decreasing overall algorithm efficiency. The work presents an analysis of the projection center in terms of precision and accuracy.
The presentation includes aspects of material design and characterization with a focus on lignin. Examples are the structural elucidation of lignosulfonates by means of two-dimensional chromatography, the mechanochemical degradation and functionalization of Kraft-Lignin with accompanying analytics. Future projects involving the incorporation of lignin into polymers will be presented.
A thousand times thinner than a human hair, nanoparticles (NPs) are finding applications in a range of modern products. However, as some can affect human health or the environment, knowing the types present is essential. Electron microscopy is the ‘gold standard’ for NP analysis, allowing identification based on manual size analysis, but a new method was required to analyse these particles quickly, accurately and in a consistent way.
Germany had been transporting spent fuel to the reprocessing plant in Sellafield and La Hague for decades until around 2005. Resulting from the obligation to take back the vitrified high-level waste from reprocessing six CASTOR® HAW28M filled with 168 canisters with radioactive waste in vitrified form were transported from Sellafield to the interim storage facility Biblis in 2020. Rail wagons were used for the transport to the port in Barrow-in-Furness, where they were loaded into a dedicated seagoing vessel, certified as INF Class 3 according to the INF Code. This was the first time that vitrified high level waste with considerable heat load was transported under a German design approval certificate.
BAM was involved in the authority assessment of the conditions for the sea transport. For the first transport BAM required among others, assessment of temperature distribution during transport, logging of temperatures of cargo bays and graphical imaging of temperatures of the bay with the cask in order to ensure compliance with temperature specifications, e.g. maximal neutron absorber and gasket temperatures. Special interest was taken in the identification of possible events exceeding the specified temperatures considering the different philosophies of IMDG code and its supplement INF code regarding temperature control of hatches. Results show compliance with assumed conditions.
This working paper summarises the current state of knowledge and research on the application of sensors in road pavements, designed to record input quantities and characteristics for structural assessment. In this working paper, sensors generally refer to technical equipment that can used to record the values of physical quantities and display them for interpretation.
The working paper deals with every type of sensor that is permanently connected to the road, i.e. sensors that are installed – in the bound and unbound courses of the superstructure as well as in the sub-base/sub-structure, – next to or above the road (for example on masts) and can contribute to structural recording and its subsequent assessment. This can also include sensors that are primarily used for a different purpose (e.g. traffic control). However, this working paper only describes the application of sensors that are installed primarily for other purposes for the sake of completeness; special publications (e.g. Notes on detection technologies in road traffic) are available for the respective installation situations.
The characterization of really unknown phases typically uses 70 to 150 reflectors for lattice metric calculation. The determination of the lattice parameters follows with 4% accuracy. Including a Z correction up to 1% can be reached. The precision of the lattice parameters ratios (a:b:c) is, however, better than 0.1%.
The talk summarizes challenges in microplastic analysis. It shows the preparation of microplastic reference materials as well as the testing on homogeneity and stability. The reference material is used in an international laboratory comparison to compare different detection methods used for microplastic analysis. The methods used were µ-IR (FTIR+LDIR) for number-based methods and TED-GC/MS and Py-GC/MS for mass-based methods. The ILC was done under the umbrella of VAMAS TWA 45. Results of the participants are presented.
Efficient flame retardancy is often achieved only when applying synergistic multicomponent systems. Flame retardants are combined or used together with adjuvants or synergists to enhance their efficiency, reduce the amount required, or reduce the costs; fibers and fillers contribute to fire properties crucially. Although the main flame-retardant modes of action are known, the detailed scientific understanding usually falls short, when it comes to complex synergistic multicomponent systems, the important tiny optimizations, or quantifying in terms of specific fire properties. This paper tries to illuminate the concept of synergistic flame retardants. The need for the multicomponent approach and the main phenomena are described. Thought-provoking impulses are delivered on how the understanding of multicomponent systems promotes the evidence-based development of future flame retardant polymeric materials. Multicomponent systems are discussed in their capacity as general powerful strategy for achieving and optimizing flame retardant polymeric materials.
This paper is based mainly on the overall conclusions and concrete results of several projects performed in the group of the author. Thanks to my (former) students and co-operation partners in these projects. Thanks for financing to DFG (Scha 730/8-1 Scha 730/8-2, Br 3376/1-1, Scha 730/19-1), AiF IGF (438 ZN, 17833N/2, 19078 N/2), and BMBF (03X0111C, 01DN16040).
Normung und Standardisierung in der zerstörungsfreien Prüfung finden auf nationaler, europäischer und internationaler Ebene statt. Die Übernahme von Leitungsfunktionen in diesen Gremien erzeugt die Möglichkeit der Steuerung von Themen und Inhalte der relevanten Normen. Das persönliche Engagement der Fachexpert*innen in den nationalen Gremien und den europäischen und internationalen Arbeitsgruppen ist ein zusätzlicher Faktor für die inhaltliche Korrektheit und die erwünschte inhaltliche Ausrichtung der Norm. Denn wer nicht normt wird genormt und muss letztlich Regeln verwenden, die andere entsprechend ihrer eigenen Interessen gestalten. Voraussetzung für die Teilnahme in europäischen und internationalen Normungsgremien ist die Mitwirkung in den entsprechenden DIN-Spiegelgremien, welche die europäischen (CEN) und internationalen (ISO) Aktivitäten spiegeln und die Fachexperten für die Mitarbeit autorisieren. Auf internationaler Ebene findet die Normungsarbeit in den technischen Komitees ISO/TC 135 “Non-destructive testing” und ISO/TC 44/SC 5 “Testing and inspection of welds” und ihren Arbeitsgruppen statt. Das europäische Pendant ist das CEN/TC 138 “Zerstörungsfreie Prüfverfahren” mit seinen Arbeitsgremien. Die DIN-Spiegelgremien sind für die deutsche Mitarbeit in diesen Gremien und die inhaltliche Bewertung der Norm-Entwürfe zuständig.
Motivated by the aim of developing an additive manufacturing (AM) technology easily integrated in the process chains of the ceramic industry, the LSD-print technology was conceived as a slurry-based variation of binder jetting (BJ).
BJ and other powder bed technologies (such as powder bed fusion) are amongst the most successful AM techniques, especially for metals and polymers, thanks to their high productivity and scalability. The possibility to use commercially available feedstocks (in the form of powders or granules) makes BJ also attractive for ceramic materials. The application of these techniques to most advanced ceramics has however been difficult so far, because of the limitations in depositing homogeneous layers with fine, typically poorly flowable powders.
In this context, the "layerwise slurry deposition" (LSD) was proposed at TU Clausthal (Germany) as a slurry-based deposition of ceramic layers by means of a doctor blade. Combined with layer-by-layer laser sintering of the material, the LSD process was originally demonstrated for the rapid prototyping of silicate ceramics. Due to the difficulties in controlling the microstructure and the defect formation in laser-sintered technical ceramics, the LSD process was later combined with inkjet printing in the LSD-print technology, which has been further developed at BAM (Germany) in the past decade.
The LSD-print technology combines the high speed of inkjet printing, typical of BJ, with the possibility of producing a variety of high-quality ceramics with properties comparable to those achieved by traditional processing. Due to the mechanical stability of the powder bed, the process can also be carried out with continuous layer deposition on a rotating platform, which further increases its productivity.
This presentation will delve into 10 years of research on the LSD-print of a wide variety of technical ceramics including alumina, silicon carbides and dental ceramics. The discussion highlights how a seemingly small process and feedstock modification (from powders to slurries) has great influence on the challenges and potential of this process, which are being addressed on its path to industrialization.
Multiphoton lithography (MPL), an emerging microfabrication technique, shows great potential in a variety of applications ranging from tissue engineering to soft micro-robotics. Fabricated micro-objects often are expected to undergo shape morphing or bending. Furthermore, ensuring precise property tuning becomes detrimental for the functionality of MPL microstructures. Herein, we present novel MPL materials based on interpenetrating networks (IPNs), which effectively combine the advantages of acrylate and epoxy thermoset systems. A library of 3D MPL IPN microstructures with high 3D structural stability and tailored thermal and micromechanical properties is achieved. MPL laser velocity and fabrication power can be used to tune the morphology and therefore properties of IPN. New IPN microstructures with materials Young's moduli of 4 to 6 MPa demonstrate susceptibility to deformation with high to fully elastic response. Such soft elastic materials hold immense promise within morphable microsystems, soft micro-robotics and cell engineering applications.
Powder bed technologies are amongst the most successful Additive Manufacturing (AM) techniques. The application of these techniques to most ceramics has been difficult so far, because of the challenges related to the deposition of homogeneous powder layers when using fine powders.
In this context, the "layerwise slurry deposition" (LSD) has been developed as a layer deposition method enabling the use of powder bed AM technologies also for advanced ceramic materials. The layerwise slurry deposition consists of the layer-by-layer deposition of a ceramic slurry by means of a doctor blade, in which the slurry is deposited and dried to achieve a highly packed powder. Not only very fine, submicron powders can be processed with low organics, but also the dense powder bed provides excellent support to the parts built. The LSD technology can be combined with binder jetting to develop the so-called “LSD-print” process. LSD-print combines the high-speed printing of binder jetting with the possibility of producing a variety of high-quality ceramics with properties comparable to traditional processing.
The latest development of this technology shows that it is possible to print ceramic parts in a continuous process by depositing a layer onto a rotating platform, growing a powder bed following a spiral motion. The unique mechanical stability of the layers in LSD-print allows to grow a powder bed several centimeters thick without any lateral support. The continuous layer deposition allows to achieve a productivity more than 10X higher compared to the linear deposition, approaching a build volume of 1 liter/hour.
Since microplastics (MPs) can be found everywhere and are becoming a problem of high concern, it is necessary to understand their physico-chemical properties. To obtain reliable analytical data a set of validated methods for sampling, sample preparation, detection, and data evaluation are needed.
To meet these needs an interlaboratory comparison (ILC) with 84 participants worldwide has been organized under the international pre-standardisation platform VAMAS (www.vamas.org/twa45/) as Project 2 “Development of standardized methodologies for characterisation of microplastics with microscopy and spectroscopy methods” within the Technical Working Area TWA 45 “Micro and Nano Plastics in the Environment”. In this ILC thermo-analytical methods (Py-GC/MS and TED-GC/MS) and vibrational methods (µ-Raman and µ-FTIR) have been tested and compared by providing a set of microplastic representative test materials and measurement protocols developed at BAM. The defined measurands were: particle number concentration, particle size distribution (PSD), and polymer identity and mass content. To increase the statistical quality, 6 samples were shipped together with blank samples. Hence, the ILC provides information on precision and accuracy of the results obtained with different methods as well as strengths and limitations of the proposed protocols.
The development of standards that include simulation models is often based on heuristics that include experimental data that is used to calibrate and validate the simulation models. However, these data and the corresponding calibration procedures are usually not part of the publicly accessible documentation making it very difficult to identify gaps in the current standard or extend it to new innovative solutions. The poster shows an adapted procedure that integrates the complete process into a database and a workflow to be published alongside the standard.
Fully automated and decentralized fused filament fabrication of ceramics for remote applications
(2024)
Manufacturing of ceramic components in remote (i.e., geographically isolated) settings poses significant challenges where access to conventional manufacturing facilities is limited or non-existent. Fused Filament Fabrication (FFF) enables the rapid manufacturing of ceramic components with complex geometries. Parts formed by FFF require subsequent debinding and sintering to reach full density. Debinding and sintering are typically executed in separate steps with different equipment, necessitating extensive human handling which hinders process automation and may be challenging for the operator in isolated environments. This poster presents an innovative approach: the integration of all process steps into a single, fully automated system, streamlining the process and minimizing human involvement. Our system combines a dual extrusion filament printer with a porous and heat-resistant ceramic print bed. The porous print bed enables mechanical interlocking of the first printed layers, ensuring adhesion and structural integrity during FFF. Ceramic parts are printed onto thin sacrificial rafts, which are built using an interface material with the same binder as the ceramic filament. After the print is completed, the heat-resistant print bed with all parts is transferred seamlessly with a carrier system into a high-temperature furnace for debinding and sintering. During sintering the sacrificial raft is disintegrated, allowing for unconstrained sintering of the ceramic parts and easy removal of the finished parts. In conclusion, our integrated approach enables significant advancements in the fabrication of complex ceramic components in remote environments with increased efficiency and minimal human handling.
The Laser-Induced Slip Casting is an additive manufacturing technology specifically developed for ceramic materials using water-based ceramic slurries. The process takes place layer-by-layer in a similar fashion as top-down vat photopolymerization, selectively consolidating each layer by means of a laser energy source positioned on the top. Contrary to vat photopolymerization, in which the consolidation is achieved by selectively cross-linking a ceramic-filled resin, LIS uses water-based slurries with a low amount of organic additives (typically < 5 wt%) as feedstocks.
In LIS, a green body is formed by local evaporation of water which causes the suspension to collapse forming a cast, following a mechanism similar to slip casting. Only a small content of organic additives is needed to effectively disperse the ceramic particles and to increase the green strength.
The technology is very versatile and can be applied to all ceramic systems that can be dispersed in water. One of the main advantages is that even dark materials such as silicon carbide can be processed without issues related to light scattering and absorption.
The presentation will discuss strengths and limitations of LIS compared to other AM technologies and will highlight the latest results for alumina and for silicon carbide ceramics.
Blast injuries are among the most common injuries in military operations. Also, in civilian environments, more explosive threats are expected in the future due to emerging conflicts and threats. While the effect of fragments, which is classified as secondary blast injury, could be minimized by police and military personnel’s modern ballistic body protection systems, the effects of shock wave propagation in the body as part of the primary explosion trauma still remain a serious threat needing further research.
The detonation-physical processes of highly dynamic pressure changes within the human body, the reflection-related amplification of shock waves at organ-dermis interfaces, and the consequences of injury mechanisms have become more prominent in international research. Various approaches have been used to investigate these aspects. Animal experiments on free field test sites or shock tube setups combined with a subsequent biological evaluation and numerical simulations provided promising results and allowed the discussion of different biomechanical aspects. However, due to poor reproducibility and a lack of short-term dynamic material properties, most research approaches have significant limitations. Laboratory test setups do not represent real-scale high explosive detonation parameters with regards to pressure characteristics, impulse duration and blockage problems. Measured values are interpreted with partly outdated, selective and not validated limit values for overpressures from field tests with animals. This is due to the lack of a validated and comprehensive data set covering a variation of the crucial parameter. Injury mechanisms and their effects have not yet been sufficiently elucidated for the torso and extremities.
In order to contribute to the research efforts on the primary explosion effects, the German Federal Armed Forces established an interdisciplinary military medical research project in cooperation of the Bundeswehr Hospital Berlin and the German Federal Institute for Materials Research and Testing (BAM). The aim of the planned investigation is the development of a multidisciplinary method to investigate shock wave behavior in various generic tissue simulants under the most reproducible conditions possible with realistic loads in an experimental test series with short set-up times.
The presentation will start with an overview of ceramic additive manufacturing (AM) technologies and will discuss the potential of AM in the field of bioceramics.
The presentation will then focus on two possible use cases of binder jetting technologies.
In the first example, standard powder-based binder jetting is used to manufacture a porous implant design for large scale bone defects. The related challenges in the process chain will be discussed, from powder synthesis to sintering and characterization of the printed part.
In the second example, the LSD-print slurry-based binder jetting technology is presented as a possibility to adapt powder-bed AM to produce dense ceramic parts. The use case will focus on an application in the field of dental ceramics, specifically for the manufacturing of patient individualized single tooth restorations (veneers, crowns) with a high throughput process chain.
Der Bau von Gründungs- und Turmstrukturen für Windkraftanlagen erfordert den Einsatz moderner, nachhaltiger und ressourcenschonender hochfester Feinkornbaustähle. Durch den Schweißprozess verursachte Schweißnahtfehler sind nicht akzeptabel. Um diese zu beheben, ist das lokale thermische Fugenhobeln mit anschließendem Reparaturschweißen ein gängiges und wirtschaftliches Verfahren. Die hohe Schrumpfbehinderung um die ausgefugte Nut durch das umgebende Gefüge kann zu Rissbildung führen, wenn sich konstruktiv bedingte Spannungen und Eigenspannungen aus der Reparaturschweißung überlagern. Diese Gefahr wird durch die Verschlechterung der Mikrostruktur und der mechanischen Eigenschaften hochfester Stähle während des Schweißreparaturprozesses noch verstärkt.
Der Vortrag stellt die wesentlichen Inhalte sowie die wichtigsten Änderungen der TRGS 510 "Lagerung von Gefahrstoffen in ortsbeweglichen Behältern" vor.
Die TRGS 510 zeichnet sich durch ein gestuftes Maßnahmenkonzept in Abhängigkeit von der Art und Menge der gelagerten Gefahrstoffe aus. Folgende Maßnahmenstufen werden durch die TRGS 510 beschrieben:
1. Kleinmengen -> Allgemeine Maßnahmen
2. Überschreitung der Kleinmengen -> Lagerung im Lager
3. Überschreitung bestimmter Mengen für spezielle Gefahrstoffe -> Spezielle Maßnahmen
4. Verschiedene Gefahrstoffe und Lagerung im Lager erforderlich -> ggf. Getrenntlagerung und Separatlagerung
Following directly from the information presented at IFBIC 2023 on the research project 'Investigation of intracorporeal shock wave propagation using a simplified torso model and a shock wave generator', the latest results are presented below [1]. In order to contribute to the research efforts on the primary explosion effects, the aim of the investigation is the development of a multidisciplinary method to investigate shock wave behavior in various generic tissue simulants under the most reproducible conditions possible with realistic loads in an experimental series with short set-up times.
To achieve this, an autoclave with a volume of 0.065 m3 is used to generate reproducible pressure waves (Fig. 1). The autoclave will be referred to as Shockwave Generator (SWG). The pressure wave is produced by the detonation of a stoichiometric mixture of acetylene and oxygen under atmospheric conditions. The SWG-outlet is sealed by a rupture disc, which can be adjusted in thickness to vary the initial pressure. Additionally, modifying the composition of the acetylene-oxygen mixture can result in different load cases. The SWG requires approximately 30 minutes of set-up time between trials. The SWG was adjusted to match the characteristics of a real and typical explosive through free-field measurements. The experiments demonstrated that the pressure wave propagates in a hemispherical shape and has sufficient reproducibility.
To represent soft tissue, a basic model made of homogeneous ballistic gelatin is used in a geometrically simplified torso model (STM) (Fig. 2). The STM was enlarged to outer dimensions of 400 x 250 x 240 mm. Viscoelastic behavior of the ballistic gelatin can be assumed due to the collagen structure [2]. The density of the ballistic gelatin, and therefore the sound velocity, can be adjusted by changing the mixing ratio. Simplified simulants, such as hollow and solid material (bone simulant), were embedded in the STM. Additionally, the STM has been tested as a carrier material for biological substances, such as indicator species. The next step is to test the STM as a carrier material for larger organic tissue structures such as lungs or kidneys. The organic tissue samples will undergo histological examination to analyze their structural changes afterwards. The STM is equipped with embedded piezoelectric pressure sensors, an accelerometer and a temperature sensor. Visual documentation is captured using a high-speed camera. This measurement setup allows for the tracking of the coupled pressure wave and its behavior within the model and at the media transitions. Pressure values can be recorded after certain media changes, such as from soft tissue to a solid material (Figure 3).
The following is a review of the optimizations made to the entire experimental setup. The reproducibility of the SWG was increased. This was achieved by extending the evacuation process to the entire feed system of the SWG. Nitrogen residues in the SWG system can thus be avoided. As a result, the double peaks that occur at the first maximum can be avoided, as combustion runs more evenly without the nitrogen residues. In addition, partially varying peak overpressures can be avoided, as the acytelene-oxygen mixture is not too lean due to the elimination of the nitrogen residues. The workflow has been streamlined, resulting in an average set-up time of 25 minutes for the SWG. In the case of the STM, the manufacturing process in particular was optimized by examining and defining the manufacturing process based on scientific publications, which increases the reproducibility of the STM base bodies. As already mentioned in the previous paragraph, the STM was equipped with various additives in order to investigate the transition behavior of the pressure wave.
The following trail serves as an example: A comparison is made between the STM in the basic structure (Fig. 2 l.s.) and with an embedded solid material (bone plate) (Fig. 3 l.s.). An external overpressure of 100 kPa is generated by the SWG at a distance of 1 m, where the STM is placed. For the basic STM structure, the sensor distance is consistently 100 mm. The internal overpressure is visible in Fig. 2 r.s.. A typical ideal pressure curve can be seen. The characteristic points are easily distinguishable from the reflection peaks. In the STM with an embedded solid material, the sensor distance remains consistently at 66.6 mm
Per- and polyfluoroalkyl substances (PFAS) were classified as a group of highly concerning chemicals over the last decades. Because of the high persistence of PFAS, their previous use led to contamination of the environment and human population. Due to ongoing use and incomplete remediation or destruction methods, the PFAS background in the environment is growing continuously.
The presence of ultrashort PFAS (with ≤3 carbon atoms) in the environment is often overlooked despite their contributions to PFAS levels. These compounds may directly contaminate the environment and arise from degradation of polyfluorinated compounds as well as incomplete PFAS destruction in certain industrial processes. Nonetheless, few approaches for targeted analysis of ultrashort PFASs have been developed, except for trifluoroacetic acid (TFA). Beside liquid (LC-MS/MS), supercritical fluid (SFC-MS/MS), and ion chromatography (IC-MS)-based systems, gas chromatography coupled with mass spectrometry (GC-MS) is a promising method for detection and quantification of ultrashort PFAS.
The goal of this study was to develop a simple headspace GC-MS method for the quantification of ultrashort perfluorocarboxylic acids (PFCAs) and polyfluorinated alcohols (PFOHs) in water samples. In contrast to PFOHs, functionalization of PFCAs was required for quantification. This was done by esterification with methanol at 80 °C, which can be carried out directly in the headspace GC-MS system.
Moreover, several parameters were optimized to achieve a low limit of quantification (LOQ) for the analytes used: i) The ratio of the aqueous solution, methanol, and available gas phase within the analysis vessel, ii) the concentration of additional acid in esterification mixtures of PFCAs, iii) shaking frequency and iv) shaking time before analysis. After optimizing the procedure, we were able to quantify ultrashort PFCAs and PFOHs. Thus, our developed headspace GC-MS method has the potential to be used as an alternative target analysis for ultrashort-chain PFCAs and PFOHs in various water samples (groundwater, wastewater).
Since microplastics (MPs) can be found everywhere and are becoming a problem of high concern, it is necessary to understand their occurrence and fate in the environment. However, to obtain data of high quality is very challenging, since measurement operating procedures differ from laboratory to laboratory. Currently, there are no standardized methods to analyze microplastics. One promissing possibility to adress standardization of the methodology and operating procedures are interlaboratory comparisons (ILCs). In this contribution we report the first results of an ILC on microplastic detection methods organized under the pre-stantdardisation plattform of VAMAS (www.vamas.org/twa45/) as Project 2 “Development of standardized methodologies for characterisation of microplastics with microscopy and spectroscopy methods”, within the Technical Working Area TWA 45 “Micro and Nano Plastics in the Environment”. The ILC has gathered 84 participants all over the world representing all continents. BAM, as the project leader, produced a set of reference microplastic materials, which have been distributed to all the participants together with the measurement protocols and reporting data templates.
Microplastic and nanoplastic particles (MNP) are spread all over the world in various types, shapes and sizes making it very challenging to accurately analyse them. Each sampling procedure, sample preparation method and detection technique needs suitable reference materials to validate the method for accurate results. Furthermore, the effects of these MNPs should be evaluated by risk and hazard assessment with test particles close to reality. To better understand MNP behavior and aid in clarification of their interactions with organisms, we produced several MNP materials by top-down procedure and characterized their properties. Since surface properties mostly determine particles’ toxicity, the aim of the present study was to determine which functional groups are present on MNPs and how the surface can be affected by the production process and particle’s environment.
Preliminary results of an interlaboratory comparison on microplastics organised by plasticsfate
(2023)
Microplastics are everywhere in the environment, but analytics is challenging. Since harmonisation is missing as well es suitable reference materials, BAM did under th umbrella of VAMAS funded by the EU Horizon 2020 project PlasticsFate a ILC for microplastic detection methods. Methods adressed were IR, Raman, Py-GC/MS and TED-GC/MS. The talk gives a first presentation and evaluation on the results.
Monitoring of microplastics in food matrices is crucial to determinate the human exposure. By direct ingestion microplastics could be released in the food during the production, through packaging and by consumer’s use. The absence of standard methods to quantify and detect different size range and type of microplastics has led to difficult and time consuming procedural steps, poor accuracy and lack of comparability. In this work, matrix characterization and laboratory experiments were used to investigate the efficiency of sample preparation in milk powder. This information is crucial to compile a standard procedure for sample preparation and digestion of common milk powder to detect different particle sizes and types of polymers. Charaterisation is done by TGA and TOC measurements.
Rotational rheometry test of Portland cement-based materials - A systematic literature review
(2024)
This study systematically reviews 62 papers on the use of rotational rheometry to assess the fresh state behavior of Portland cement-based materials. The research highlights the wide variation in test methods and aims to provide a comprehensive overview. Findings reveal that 50.0% of studies employed vane geometry, despite its limitations in providing transformation equations. Regarding dynamic shearing tests, 67.0% followed a consensus using a pre-shearing step and a step-wise routine with stabilization times ≥ 10 s. While the Bingham model is commonly used, the study emphasizes the importance of considering shear-thinning behavior in cementitious materials. Models like Herschel-Bulkley and modified Bingham may be more appropriate. This review offers insights into testing conditions for rotational rheometry of cementitious materials, serving as a foundation for future research in the field.
For the hydrogen-based energy economy of tomorrow, the construction of the necessary infrastructure will play a central role. Most materials used to date, such as welded steels, can be prone to hydrogen embrittlement under certain conditions. This includes the classic delayed cold cracking during welding as well as degradation phenomena during service of components in hydrogen-containing environment. For the evaluation of any hydrogen effect, for example, on the mechanical properties of a welded metallic material, the hydrogen content must be precisely determined. In the case of weld seams, the carrier gas hot extraction (CGHE) according to ISO 3690 is meanwhile state-of-the-art. CGHE is based on accelerated hydrogen degassing due to the thermal activation of hydrogen at elevated temperatures. In addition to the quantification of hydrogen, thermal desorption analysis (TDA) with varying heating rates can be used to determine and evaluate the hydrogen trapping at microstructural defects in the material. For both techniques, experimental and metrological influences must be considered, which have a major effect on the result. For example, ISO 3690 suggests different sample geometries and minimum extraction times for CGHE. This study summarizes the results and experiences of numerous investigations at the Federal Institute for Materials Research and Testing (BAM) with different sample temperatures and geometries (ISO 3690 type B and cylindrical TDA samples) regarding the influence of the sample surface (polished/welded), measurement accuracy depending on the sample volume and the insufficient monitoring of the effect of PI control on the extraction temperature. A deviating extraction temperature from the target temperature can significantly falsify the measurement results. Based on the results, methods are shown which allow the desired extraction temperature to be reached quickly without physically interfering with the measuring equipment. This serves to significantly improve the reliability of the hydrogen measurement through increased signal stability and accelerated hydrogen desorption. In general, an independent temperature measurement with dummy samples is recommended for the heating procedure of choice to exclude possible undesired temperature influences before the measurement. The methods described can be transferred directly to industrial applications
Die Transformation der Energienutzung von konventionellen zu erneuerbaren Quellen führt dazu, dass zukünftig mehr Energie effizient zwischengespeichert werden muss. Eine Möglichkeit der elektrochemischen Zwischenspeicherung bieten Lithium-Ionen-Batterien. Hierfür können ausgemusterte Automobilantriebsbatterien verwendet werden. Erfüllen sie die hohen Anforderungen des mobilen Bereichs nicht mehr, haben sie oftmals noch eine ausreichende Kapazität und Leistungsfähigkeit für die stationäre Zwischenspeicherung.
Neben der Verwendung der Batterien im größeren Maßstab, z.B. bei Energieversorgern, werden durch den vermehrten Einsatz von Photovoltaik-Anlagen in Ein- und Mehrfamilienhäusern verstärkt Zwischenspeicher für Privathaushalte nachgefragt. Dies birgt auch für Einsatzkräfte neue Herausforderungen in der Gefahrenabwehr.
Im vom Bundesministerium für Bildung und Forschung (BMBF) geförderten Verbundprojekt „SEE-2L – Sicherheit elektrochemischer Energiespeicher in Second Life Anwendungen“ wurden Versuche mit Second Life Modulen durchgeführt. Verbundpartner im Projekt waren neben der vfdb die Otto-von-Guericke-Universität Magdeburg und die Bundesanstalt für Materialforschung und -prüfung. Zudem war das Institut der Feuerwehr Nordrhein-Westfalen eingebunden.
Die durchgeführten Versuche bilden eine Grundlage für die Einordnung der Batteriespeicher, z.B. aus Sicht des baulichen Brandschutzes, zur Methodik der Brandbekämpfung oder zur Risikobewertung hinsichtlich der Prozess- und Anlagensicherheit.
Im Beitrag werden die Versuchsergebnisse vorgestellt und Ansätze für deren Anwendung gezeigt. Um die gewonnenen Erkenntnisse zu vermitteln, wurde im Projekt zudem ein Schulungskonzept für Einsätze mit Lithium-Ionen-Technologien erarbeitet, das im Beitrag präsentiert wird. Es besteht aus theoretischen und praktischen Anteilen, sodass bei den Feuerwehren praxisnah aus- bzw. fortgebildet werden kann.
Replacing antimony trioxide (ATO) in flame retardant formulations is an urgent task due to its toxicity. There are indications that calcium hypophosphite (CaP) may be a promising replacement. This study investigates the decomposition, fire behavior, and smoke release of brominated flame-retarded acrylonitrile butadiene styrene (ABS) under various fire scenarios like ignition, developing fire and smoldering, while replacing ATO with CaP and CaP/talc. Adding 4 wt.-% of talc to CaP formulations showed beneficial effects on flammability due to changes in the viscosity and barrier properties. Synergism between 8 wt.-% talc and CaP improved the protective layer in the developing fire scenario, resulting in a ∼60 % decrease in the peak of heat release rate and reduction of ∼21 % in total smoke production (ref. ABS+Br+ATO). With a conventional index of toxicity (CIT) of below 0.75, ABS+Br+CaP passes the highest requirements according to EN 45545-2. Overall, the CaP/talc materials improve flame retardancy, show less smoke emission under forced flaming conditions, and prevent chronic intoxication and environmental pollution through smoke particles contaminated with antimony.
Based on the state-of-the-art research and regulations, the application of the fracture mechanics master curve (MC) concept to ferritic ductile cast iron (DCI) is being investigated in a joint research project between MPA Stuttgart and BAM Berlin. This paper outlines the research approach, the planned investigations and first results of the experimental program.