TY - JOUR A1 - Kömmling, Anja A1 - Chatzigiannakis, E. A1 - Beckmann, Jörg A1 - Wachtendorf, Volker A1 - von der Ehe, Kerstin A1 - Braun, Ulrike A1 - Jaunich, Matthias A1 - Schade, U. A1 - Wolff, Dietmar T1 - Discoloration Effects of High-Dose gamma-Irradiation and Long-Term Thermal Aging of (U) HMW-PE N2 - Two polyethylene types with ultra-high (UHMWPE) and high molecular weight (HMW-PE) used as neutron radiation shielding materials in casks for radioactive waste were irradiated with doses up to 600 kGy using a 60Co gammasource. Subsequently, thermal aging at 125∘C was applied for up to one year. Degradation effects in the materials were characterized using colorimetry, UV-Visspectroscopy, IR spectroscopy, and DSC. Both materials exhibited a yellowing upon irradiation.The discoloration of UHMW-PE disappeared again after thermal aging.Therefore, the yellowing is assumed to originate fromannealable color centers in the formof free radicals that are trapped in the crystalline regions of the polymer and recombine at elevated temperatures. For the antioxidantcontaining HMWPE, yellowing was observed after both irradiation and thermal aging. The color change was correlated mainly to decomposition products of the antioxidant in addition to trapped radicals as in UHMW-PE. Additionally, black spots appeared after thermal aging of HMW-PE. KW - Irradiation KW - UHMWPE KW - Colour center KW - Yellowness index PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-423992 DO - https://doi.org/10.1155/2017/1362491 SN - 1687-9422 VL - 2017 IS - Article ID 1362491 SP - 1 EP - 10 PB - Hindawi AN - OPUS4-42399 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Le, Quynh Hoa A1 - Vestergaard, M.C. A1 - Tamiya, E T1 - Carbon-based nanomaterials in biomass-based fuel-fed fuel cells N2 - Environmental and sustainable economical concerns are generating a growing interest in biofuels predominantly produced from biomass. It would be ideal if an energy conversion device could directly extract energy from a sustainable energy resource such as biomass. Unfortunately, up to now, such a direct conversion device produces insufficient power to meet the demand of practical applications. To realize the future of biofuel-fed fuel cells as a green energy conversion device, efforts have been devoted to the development of carbon-based nanomaterials with tunable electronic and surface characteristics to act as efficient metal-free electrocatalysts and/or as supporting matrix for metal-based electrocatalysts. We present here a mini review on the recent advances in carbon-based catalysts for each type of biofuel-fed/biofuel cells that directly/indirectly extract energy from biomass resources, and discuss the challenges and perspectives in this developing field KW - Carbon-based nanomaterials KW - Biofuel cells KW - Biomass KW - Carbon nanotubes KW - Graphene KW - Carbon nanodots PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-428226 UR - http://www.mdpi.com/1424-8220/17/11/2587/htm DO - https://doi.org/10.3390/s17112587 SN - 1424-8220 VL - 17 IS - 11 SP - 2587, 1 EP - 2587, 21 PB - MDPI AG CY - Basel, Switzerland AN - OPUS4-42822 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jonietz, Florian A1 - Krankenhagen, Rainer A1 - Noack, M. A1 - Gensecke, K. A1 - Wiedenmann, E. T1 - 3D-Formbestimmung mit integrierter thermografischer Qualitätsprüfung N2 - Sowohl die 3D-Formbestimmung als auch die Thermografie sind Verfahren der Qualitätssicherung. Im vorgestellten Projekt wird versucht, die beiden Methoden zusammenzuführen. Das Prinzip des für die Formbestimmung verwendeten 3D-Scanners beruht auf dem bereits bekannten Verfahren der Streifenlichtprojektion. Die Neuartigkeit des hier verwendeten 3D-Scanners besteht darin, dass nicht im sichtbaren, sondern im infraroten Spektralbereich gearbeitet wird. Dadurch wird es möglich, nicht die Reflexion, sondern die Wärmestrahlung des Prüfobjektes nach Absorption der eingebrachten Strahlung auszuwerten. Dies ermöglicht, auch optisch „nicht-kooperative“ Oberflächen zu erfassen. Die Anregung mit Wärmestrahlung stellt das Bindeglied zum Verfahren der aktiven Thermografie für die Detektion verdeckter Schäden dar. Bei letzterem Verfahren wird der Wärmestau über Defekten beim Eindringen der Wärme in die Tiefe des Materials gemessen. Dabei stellen Defekte eine Störung des 3D-Scan-Verfahrens dar, während umgekehrt unregelmäßig geformte Oberflächen das thermografische Verfahren erschweren, d.h. der Messeffekt eines der Verfahren ist ein Störeffekt für das jeweils andere Verfahren. Es wird zum einen der Frage nachgegangen, inwieweit das 3D-Scan-Verfahren durch verdeckte thermische Defekte beeinträchtigt wird, und zum anderen die Möglichkeit untersucht, den vorhandenen 3D-Scanner auch für die aktive Thermografie einzusetzen. Es werden CFK-Proben mit künstlich eingebrachten thermischen Defekten untersucht und die Möglichkeiten und Grenzen der vorhandenen Messapparatur für die Defekterkennung aufgezeigt. T2 - DGZfP-Jahrestagung 2017 CY - Koblenz, Germany DA - 22.05.2017 KW - 3D-Formbestimmung KW - Thermografische Qualitätsprüfung KW - Streifenlichtprojektion KW - 3D-Scanner KW - Aktive Thermografie PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-407856 UR - https://jahrestagung.dgzfp.de/Portals/151//doc/Mi.1.A.3.pdf SN - 978-3-940283-85-6 VL - 162 SP - 1 EP - 9 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) CY - Berlin AN - OPUS4-40785 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Daly, M. A1 - Burnett, T. L. A1 - Pickering, E. J. A1 - Tuck, O. C. G. A1 - Léonard, Fabien A1 - Kelley, R. A1 - Withers, P. J. A1 - Sherry, A. H. T1 - A multi-scale correlative investigation of ductile fracture N2 - The use of novel multi-scale correlative methods, which involve the coordinated characterisation of matter across a range of length scales, are becoming of increasing value to materials scientists. Here, we describe for the first time how a multi-scale correlative approach can be used to investigate the nature of ductile fracture in metals. Specimens of a nuclear pressure vessel steel, SA508 Grade 3, are examined following ductile fracture using medium and high-resolution 3D X-ray computed tomography (CT) analyses, and a site-specific analysis using a dual beam plasma focused ion beam scanning electron microscope (PFIB-SEM). The methods are employed sequentially to characterise damage by void nucleation and growth in one volume of interest, allowing for the imaging of voids that ranged in size from less than 100 nm to over 100 mm. This enables the examination of voids initiated at carbide particles to be detected, as well as the large voids initiated at inclusions. We demonstrate that this multi-scale correlative approach is a powerful tool, which not only enhances our understanding of ductile failure through detailed characterisation of microstructure, but also provides quantitative information about the size, volume fractions and spatial distributions of voids that can be used to inform models of failure. It isfound that the vast majority of large voids nucleated at MnS inclusions, and that the volume of a void varied according to the volume of its initiating inclusion raised to the power 3/2. The most severe voiding was concentrated within 500 mm of the fracture surface, but measurable damage was found to extend to a depth of at least 3 mm. Microvoids associated with carbides (carbide-initiated voids) were found to be concentrated around larger inclusion-initiated voids at depths of at least 400 mm. Methods for quantifying X-ray CT void data are discussed, and a procedure for using this data to calibrate parameters in the Gurson-Tvergaard Needleman (GTN) model for ductile failure is also introduced. KW - Gurson model KW - SA508 KW - Correlative tomography KW - Void nucleation & growth KW - X-ray computed tomography PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-414547 UR - http://www.sciencedirect.com/science/article/pii/S1359645417302203?via%3Dihub DO - https://doi.org/10.1016/j.actamat.2017.03.028 VL - 130 SP - 56 EP - 68 PB - Elsevier AN - OPUS4-41454 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tatzel, Michael A1 - von Blanckenburg, F. A1 - Oelze, M. A1 - Bouchez, J. A1 - Hippler, D. T1 - Late Neoproterozoic seawater oxygenation by siliceous sponges N2 - The Cambrian explosion, the rapid appearance of most animal phyla in the geological record, occurred concurrently with bottom seawater oxygenation. Whether this oxygenation Event was triggered through enhanced nutrient supply and organic carbon burial forced by increased continental weathering, or by species engaging in ecosystem engineering, remains a fundamental yet unresolved question. Here we provide evidence for several simultaneous developments that took place over the Ediacaran–Cambrian transition: expansion of siliceous sponges, decrease of the dissolved organic carbon pool, enhanced organic carbon burial, increased phosphorus removal and seawater oxygenation. This evidence is based on Silicon and carbon stable isotopes, Ge/Si ratios, REE-geochemistry and redox-sensitive elements in a chert-shale succession from the Yangtze Platform, China. According to this reconstruction, sponges have initiated seawater oxygenation by redistributing organic carbon oxidation through filtering suspended organic matter from seawater. The resulting increase in dissolved oxygen levels potentially triggered the diversification of eumetazoans. KW - Oxygenation KW - Carbon cycle KW - Silicon stable isotopes PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-422339 DO - https://doi.org/10.1038/s41467-017-00586-5 SN - 2041-1723 VL - 8 SP - Article 621, 1 EP - 10 AN - OPUS4-42233 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stengel, Dominik A1 - Thiele, K. T1 - Measurements of downburst wind loading acting on an overhead transmission line in Northern Germany N2 - Along an overhead transmission line in Northern Germany, a unique instrumentation of anemometers and force measurements is installed. Details of this test line with wind measurements along a horizontal axis are given. A recent event of a presumable downburst wind event is analyzed by means of available data and precedent works on thunderstorm analysis. The measured response of the conductors at the suspension tower is investigated and compared with time domain simulation of a finite element model. T2 - X International Conference on Structural Dynamics, EURODYN 2017 CY - Rome, Italy DA - 10.09.2017 KW - Non-synoptic wind event KW - Downburst KW - Overhead transmission line KW - Finite element method PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-421239 DO - https://doi.org/10.1016/j.proeng.2017.09.578 SN - 1877-7058 VL - 199 IS - Supplement C SP - 3152 EP - 3157 PB - Elsevier AN - OPUS4-42123 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Winkelmann, Aimo A1 - Nolze, Gert A1 - Vespucci, S. A1 - Gunsekar, N.-K. A1 - Trager-Cowan, C. A1 - Vilalta-Clemente, A. A1 - Wilkinson, A. J. A1 - Voss, M. T1 - Diffraction effects and inelastic electron transport in angle-resolved microscopic imaging applications N2 - We analyse the signal formation process for scanning electron microscopic imaging applications on crystalline specimens. In accordance with previous investigations, we find nontrivial effects of incident beam diffraction on the backscattered electron distribution in energy and momentum. Specifically, incident beam diffraction causes angular changes of the backscattered electron distribution which we identify as the dominant mechanism underlying pseudocolour orientation imaging using multiple, angle-resolving detectors. Consequently, diffraction effects of the incident beam and their impact on the subsequent coherent and incoherent electron transport need to be taken into account for an in-depth theoretical modelling of the energy- and momentum distribution of electrons backscattered from crystalline sample regions. Our findings have implications for the level of theoretical detail that can be necessary for the interpretation of complex imaging modalities such as electron channelling contrast imaging (ECCI) of defects in crystals. If the solid angle of detection is limited to specific regions of the backscattered electron momentum distribution, the image contrast that is observed in ECCI and similar applications can be strongly affected by incident beam diffraction and topographic effects from the sample surface. As an application, we demonstrate characteristic changes in the resulting images if different properties of the backscattered electron distribution are used for the analysis of a GaN thin film sample containing dislocations. KW - EBSD KW - Channeling-in KW - Background processing KW - Center of mass KW - Backscattered electrons PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-422063 DO - https://doi.org/10.1111/jmi.12571 SN - 0022-2720 VL - 267 IS - 3 SP - 330 EP - 346 PB - Wiley & Sons, Ltd. AN - OPUS4-42206 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Łojewska, J. A1 - Rabin, Ira A1 - Pawcenis, D. A1 - Bagniuk, J. A1 - Aksamit-Koperska, M.-A. A1 - Sitarz, M. A1 - Missori, M. A1 - Krutzsch, M. T1 - Recognizing ancient papyri by a combination of spectroscopic, diffractional and chromatographic analytical tools N2 - Ancient papyri are a written heritage of culture that flourished more than 3000 years ago in Egypt. One of the most significant collections in the world is housed in the Egyptian Museum and Papyrus Collection in Berlin, from where the samples for our investigation come. The papyrologists, curators and conservators of such collections search intensely for the analytical detail that would allow ancient papyri to be distinguished from modern fabrications, in order to detect possible forgeries, assess papyrus deterioration state, and improve the design of storage conditions and conservation methods. This has become the aim of our investigation. The samples were studied by a number of methods, including spectroscopic (FTIR, fluorescent-FS, Raman) diffractional (XRD) and chromatographic (size exclusion chromatography-SEC), selected in order to determine degradation parameters: overall oxidation of lignocellulosic material, degree of polymerization and crystallinity of cellulose. The results were correlated with those obtained from carefully selected model samples including modern papyri and paper of different composition aged at elevated temperature in humid air. The methods were classified in the order SEC > FS > FTIR > XRD, based on their effectiveness in discriminating the state of papyri degradation. However, the most trustworthy evaluation of the age of papyri samples should rely on several methods. KW - Archaeometry KW - FTIR KW - XRD KW - Raman KW - Chromatography KW - Papyrology PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-428704 DO - https://doi.org/10.1038/srep46236 SN - 2045-2322 VL - 7 SP - 46236, 1 EP - 46236, 12 AN - OPUS4-42870 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Teixeira, M.M. A1 - Moreno, L.F. A1 - Stielow, B.J. A1 - Muszewska, A. A1 - Hainaut, M. A1 - Gonzaga, L. A1 - Abouelleil, A. A1 - Patan, J.S.L. A1 - Priest, M. A1 - Souza, R. A1 - Ferreira, K.S. A1 - Zeng, Q. A1 - da Cunha, M.M.L. A1 - Gladki, A. A1 - Barker, B. A1 - Vicente, V.A. A1 - de Souza, E.M. A1 - Almeida, S. A1 - Henrissat, B. A1 - Vasconelos, A.T.R. A1 - Deng, S. A1 - Vogelmayr, H. A1 - Moussa, T.A.A. A1 - Gorbushina, Anna A1 - Felipe, M.S.S. A1 - Cuomo, C.A. A1 - de Hoog, G.S. T1 - Exploring the genomic diversity of black yeasts and relatives (Chaetothyriales, Ascomycota) N2 - The order Chaetothyriales (Pezizomycotina, Ascomycetes) harbours obligatorily melanised fungi and includes numerous etiologic agents of chromoblastomycosis, phaeohyphomycosis and other diseases of vertebrate hosts. Diseases range from mild cutaneous to fatal cerebral or disseminated infections and affect humans and cold-blooded animals globally. In addition, Chaetothyriales comprise species with aquatic, rock-inhabiting, ant-associated, and mycoparasitic life-styles, as well as species that tolerate toxic compounds, suggesting a high degree of versatile extremotolerance. To understand their biology and divergent niche occupation, we sequenced and annotated a set of 23 genomes of main the human opportunists within the Chaetothyriales as well as related environmental species. Our analyses included fungi with diverse life-styles, namely opportunistic pathogens and closely related saprobes, to identify genomic adaptations related to pathogenesis. Furthermore, ecological preferences of Chaetothyriales were analysed, in conjuncture with the order-level phylogeny based on conserved ribosomal genes. General characteristics, phylogenomic relationships, transposable elements, sex-related genes, protein family evolution, genes related to protein degradation (MEROPS), carbohydrate-active enzymes (CAZymes), melanin synthesis and secondary metabolism were investigated and compared between species. Genome assemblies varied from 25.81 Mb (Capronia coronata) to 43.03 Mb (Cladophialophora immunda). The bantiana-clade contained the highest number of predicted genes (12 817 on average) as well as larger genomes. We found a low content of mobile elements, with DNA transposons from Tc1/Mariner superfamily being the most abundant across analysed species. Additionally, we identified a reduction of carbohydrate degrading enzymes, specifically many of the Glycosyl Hydrolase (GH) class, while most of the Pectin Lyase (PL) genes were lost in etiological agents of chromoblastomycosis and phaeohyphomycosis. An expansion was found in protein degrading peptidase enzyme families S12 (serine-type D-Ala-D-Ala carboxypeptidases) and M38 (isoaspartyl dipeptidases). Based on genomic information, a wide range of abilities of melanin biosynthesis was revealed; genes related to metabolically distinct DHN, DOPA and pyomelanin pathways were identified. The MAT (MAting Type) locus and other sexrelated genes were recognized in all 23 black fungi. Members of the asexual genera Fonsecaea and Cladophialophora appear to be heterothallic with a single copy of either MAT-1-1 or MAT-1-2 in each individual. All Capronia species are homothallic as both MAT1-1 and MAT1-2 genes were found in each single genome. The genomic synteny of the MAT-locus flanking genes (SLA2-APN2-COX13) is not conserved in black fungi as is commonly observed in Eurotiomycetes, indicating a unique genomic context for MAT in those species. The heterokaryon (het) genes expansion associated with the low selective pressure at the MAT-locus suggests that a parasexual cycle may play an important role in generating diversity among those fungi. KW - Black yeast KW - Comparative genomics KW - Chaetothyriales KW - Ecology KW - Evolution KW - Herpotrichiellaceae KW - Phylogeny PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-408720 DO - https://doi.org/10.1016/j.simyco.2017.01.001 SN - 1872-9797 VL - 86 IS - 1 SP - 1 EP - 28 PB - Elsevier CY - Amsterdam AN - OPUS4-40872 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hernández-Nava, E. A1 - Tammas-Williams, S. A1 - Smith, C. A1 - Léonard, Fabien A1 - Withers, P. J. A1 - Todd, I. A1 - Goodall, R. T1 - X-ray tomography characterisation of lattice structures processed by selective electron beam melting N2 - Metallic lattice structures intentionally contain open porosity; however, they can also contain unwanted closed porosity within the structural members. The entrained porosity and defects within three different geometries of Ti-6Al-4V lattices, fabricated by Selective Electron Beam Melting (SEBM), is assessed from X-ray computed tomography (CT) scans. The results suggest that horizontal struts that are built upon loose powder show particularly high (~20 x 10⁻³ vol %) levels of pores, as do nodes at which many (in our case 24) struts meet. On the other hand, for struts more closely aligned (0° to 54°) to the build direction, the fraction of porosity appears to be much lower (~0.17 x 10⁻³%) arising mainly from pores contained within the original atomised powder particles. KW - Cellular solids KW - Aqdditive manufacturing KW - Computed tomography KW - Titanium alloys PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-413689 UR - http://www.mdpi.com/2075-4701/7/8/300 DO - https://doi.org/10.3390/met7080300 SN - 2075-4701 VL - 7 IS - 8 SP - Article 300, 1 EP - 12 PB - MDPI AN - OPUS4-41368 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pavlovic, Mato A1 - Zoëga, Andreas A1 - Kurz, J. H. A1 - Zanotelli, Christina T1 - Investigations to introduce the probability of detection method for ultrasonic inspection of hollow axles at Deutsche Bahn N2 - The vast experience with the automated, ultrasonic system for the inspection of hollow railway axles used by Deutsche Bahn shows that much smaller flaws are detectable than required. This results in a number of false calls. False calls lead to unnecessary demounting and disassembling of wheelsets, which generates unnecessary additional costs. In order to adjust the sensitivity of the inspection system to reduce the number of false calls without compromising safety, the capability of the system to detect cracks needs to be comprehensively established. This capability can be quantified by using probability of detection (POD) curves for the system. The multi-parameter POD model makes it possible to include several factors that influence the crack detection in the analysis. The analysis presented in this paper shows that crack position, orientation, depth extension, and shape as well as the geometry of the axle all have influence on the ultrasonic response amplitude. For future work, calculation of the POD using multi-parameter POD model with these parameters is planned. T2 - ESIS TC24 Workshop "Integrity of Railway Structures" CY - Leoben, Austria DA - 24.10.2016 KW - Crack KW - Reliability KW - POD KW - Axle KW - Ultrasonic PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-415201 DO - https://doi.org/10.1016/j.prostr.2017.07.002 SN - 2452-3216 VL - 4 SP - 79 EP - 86 PB - Elsevier, B.V. AN - OPUS4-41520 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Auersch, Lutz T1 - Mitigation of railway induced vibration at the track, in the transmission path through the soil and at the building N2 - This contribution presents some principles and some examples of the mitigation of railway-induced ground vibrations. The principles are different for the mitigation measures at the track, in the soil or at the building. Force transfer functions of isolated and un-isolated track-soil systems, reflected and transmitted wave amplitudes at walls and trenches in the soil, and the transfer of the (free-field) vibration amplitudes to the foundation amplitudes of the building are analysed. The mitigation effect can be calculated by exact or simplified formulas. Some examples with 3D (finite-element boundary-element), 2D (beam-on-support), and 1D track models, 2D and 1D soil models, detailed 3D building models and finite or infinite 1D wall-floor models are investigated to find out if simple models can be used for a satisfactory prediction of the mitigation effect. The 1D track examples show that the force transfer of the track without vehicle can be exactly calculated, whereas the total force transfer can be calculated approximately if appropriate wheelset masses per track length are used for the isolated and the un-isolated track. The mitigation effect of a filled trench is calculated by a 2D finite element model and the results compare with simple transmission formula if the stiffness per area rather than the wave impedances are used for the infill material. The base isolation of a building is analysed by a detailed 3D model and the results are similar to the analytic results of a single wall with floors on the soil. Other reduction measures as different floor and column dimensions are usually less effective so that the clearly best mitigation solution at a building is a partly or a complete base isolation. T2 - X INTERNATIONAL CONFERENCE ON STRUCTURAL DYNAMICS (EURODYN 2017) KW - Mitigation KW - Soil-building interaction KW - Base isolation KW - Ground vibration PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-420869 DO - https://doi.org/10.1016/j.proeng.2017.09.192 SN - 1877-7058 VL - 199 SP - 2312 EP - 2317 PB - Elsevier CY - London AN - OPUS4-42086 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Auersch, Lutz A1 - Said, Samir A1 - Müller, Roger T1 - Measurements on the vehicle-track interaction and the excitation of railway-induced ground vibration N2 - Two railway measurement campaigns have been performed in Germany and Switzerland which yield insight in the vehicle-track-soil interaction. The campaign in Germany has included simultaneous measurement of vehicle, track, and soil vibrations during train runs with 16, 25, 40, 63, 80, 100, 125, 140, 160 km/h, and impulse measurements of the passenger car, three track sections and the soil. Two ballast tracks, one on the soil surface and one on a concrete bridge, have been investigated as well as a slab track in a tunnel. Ten different sites in Switzerland have been measured for soil properties and train-induced ground vibrations, which allow to determine the excitation forces of the railway traffic. New axle-box measurements at some of the Swiss sites have been analysed to get further experimental evidence. All these measurements have been evaluated to characterize the excitation processes. Relations between vehicle vibration and ground vibration can be observed. The vehicle vibrations, namely the accelerations of the wheelsets, yield the dynamic forces due to the passage over the irregularities of the vehicle and the track. The ground vibrations are correlated to these dynamic forces to a certain extent. Some mid-frequency ground vibration amplitudes, however, are higher than expected from the dynamic excitation forces. The experimental observations can be explained by an irregular response to the passage of the static loads, that means the passage of the static loads over an irregular ballast or soil. This correct understanding of the excitation processes is important for the prediction as well as for the mitigation of railway induced ground vibrations. T2 - X INTERNATIONAL CONFERENCE ON STRUCTURAL DYNAMICS (EURODYN 2017) KW - Vehicle-track interaction KW - Ground vibration KW - Track vibration KW - Railway measurement campaign KW - Axle box measurements PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-420889 DO - https://doi.org/10.1016/j.proeng.2017.09.390 SN - 1877-7058 VL - 199 SP - 2615 EP - 2620 PB - Elsevier CY - London AN - OPUS4-42088 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Auersch, Lutz T1 - Simultaneous measurements of the vehicle, track, and soil vibrations at a surface, bridge, and tunnel railway line N2 - A complex measuring campaign has been performed including the simultaneous measurement of vehicle, track, and soil vibrations during train runs at 16, 25, 40, 63, 80, 100, 125, 140, 160 km/h, and impulse measurements of the passenger car, three track sections and the soil. A ballast track on the soil surface and on a concrete bridge have been investigated as well as a slab track in a tunnel. The evaluation and comparison of all these data shows a generally good agreement for all components if the strong low- and high-frequency cut-off characteristics of the layered and damped soil are incorporated. There is a strong causal correlation between the vehicle and the soil by the dynamic excitation forces and a weak relation between the track and the soil by the axle-sequence spectrum of the train. However, the similarity between the axle-impulse spectrum observed at the track and the spectra of the ground vibration lead to the special excitation component of “scattered axle impulses” which is pre-dominant at the far-field points of the soil. KW - Railway KW - Ground vibration KW - Vehicle-track interaction KW - Track-soil interaction KW - Measurements PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-410224 DO - https://doi.org/10.1155/2017/1959286 VL - 2017 IS - ID 1959286 SP - 1 EP - 18 PB - Hindawi CY - Indien AN - OPUS4-41022 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dutto, Paola A1 - Stickle, M. M. A1 - Pastor, M. A1 - Manzanal, D. A1 - Yague, A. A1 - Tayyebi, S. A1 - Lin, C. A1 - Elizalde, M. D. ED - Cervera, Miguel T1 - Modelling of fluidised geomaterials: the case of the Aberfan and the Gypsum tailings impoundment flowslides N2 - The choice of a pure cohesive or a pure frictional viscoplastic model to represent the rheological behaviour of a flowslide is of paramount importance in order to obtain accurate results for real cases. The principal Goal of the present work is to clarify the influence of the type of viscous model—pure cohesive versus pure frictional—with the numerical reproduction of two different real flowslides that occurred in 1966: the Aberfan flowslide and the Gypsum tailings impoundment flowslide. In the present work, a depth-integrated model based on the v-pw Biot–Zienkiewicz formulation, enhanced with a diffusion-like equation to account for the pore pressure Evolution within the soil mass, is applied to both 1966 cases. For the Aberfan flowslide, a frictional viscous model based on Perzyna viscoplasticity is considered, while a pure cohesive viscous model (Bingham model) is considered for the case of the Gypsum flowslide. The numerical approach followed is the SPH method, which has been enriched by adding a 1D finite difference grid to each SPH node in order to improve the description of the pore water evolution in the propagating mixture. The results obtained by the performed simulations are in agreement with the documentation obtained through the UK National Archive (Aberfan flowslide) and the International Commission of large Dams (Gypsum flowslide). KW - Aberfan flowslide KW - SPH KW - Landslide propagation modelling KW - Perzyna viscoplasticity PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-410493 DO - https://doi.org/10.3390/ma10050562 SN - 1996-1944 VL - 10 IS - 5 SP - 562, 1 EP - 562, 21 AN - OPUS4-41049 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mooshofer, H. A1 - Boehm, Rainer A1 - Heinrich, W. A1 - Fendt, K. A1 - Goldammer, M. A1 - Kolk, K. A1 - Vrana, J. T1 - Amplitudenbasierte Fehlergrößenbewertung mit SAFT: Auf dem Weg von der bildlichen Darstellung zum Messverfahren N2 - Die Größenbewertung von Anzeigen und die Bestimmung der Nachweisgrenze spielen bei der Ultraschallprüfung eine zentrale Rolle: Sie stellen sicher, dass kritische Ungänzen erfasst und bruchmechanisch behandelt werden können. Bei SAFT wurde bisher die Größe von Ungänzen dadurch bestimmt, dass die räumliche Anzeigenausdehnung im Rekonstruktionsergebnis ausgewertet wird, d.h. die Anzahl von Voxel über die sich eine Anzeige erstreckt. Auf diese Weise lassen sich jedoch nur Defektanzeigen bewerten, die größer oder gleich der Wellenlänge sind. Bei kleinen Defekten versagt diese Methode, d.h. es ist keine Größenbewertung möglich. Außerdem bietet diese Methode keine Aussage über die Nachweisgrenze des Verfahrens. Ein Hauptvorteil von SAFT gegenüber der konventionellen Ultraschallprüfung ist aber gerade die Verbesserung der Nachweisgrenze, denn SAFT steigert das Signal-Rausch-Verhältnis (SNR) gegenüber dem Gefügerauschen und reduziert statistisches Rauschen. Um diesen Hauptvorteil nutzen (und quantifizieren) zu können, wird für SAFT eine Methode zur Nachweisgrenzenbestimmung und zur Größenbewertung der Anzeigen kleiner Ungänzen benötigt. Neben ihrer räumlichen Ausdehnung lassen sich Anzeigen im SAFT-Ergebnis auch durch ihre Amplitude charakterisieren, wenn die Prüfkopfeigenschaften und die geometrischen Verhältnisse beim Scan berücksichtigt werden. Genauer gesagt durch die Amplitudensumme, in die - neben der Echoamplitude - auch die winkelabhängige Streucharakteristik eingeht. Im Folgenden wird dargelegt, dass sich die Amplitudensumme zur Nachweisgrenzenbestimmung und zur Größenbewertung kleiner Ungänzen eignet. Es wird der Zusammenhang zwischen der Amplitudensumme und der Größe von Ungänzen dargestellt, und es wird gezeigt, dass auch die Anzeigenposition und die Form des Prüfobjektes eine Rolle spielen können. Auf dieser Basis wird eine Methode zur Größenbestimmung kleiner Anzeigen im SAFT-Ergebnis entwickelt. Damit lässt sich das SAFT-Ergebnis als Ersatzfehlergröße darstellen, so wie das bei konventioneller Ultraschallprüfung z.B. mit Hilfe von AVG-Diagrammen erfolgt. Durch die Vervollständigung um die Größenbewertung ist SAFT nicht mehr nur ein bildgebendes Verfahren, sondern es kann vielmehr als vollwertiges Messverfahren dienen. T2 - DGZfP-Jahrestagung 2017 CY - Koblenz, Germany DA - 22.05.2017 KW - Synthetic aperture focussing technique (SAFT) KW - Defektgrößenbewertung KW - Gewichtete Amplitudensumme KW - Kleine Reflektoren PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-411571 SN - 978-3-940283-85-6 VL - 162 SP - 1 EP - 9 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) CY - Berlin AN - OPUS4-41157 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cuéllar, Pablo A1 - Benseghier, Z. A1 - Luu, L.-H. A1 - Bonelli, S. A1 - Delenne, J.-Y. A1 - Radjai, F. A1 - Philippe, P. T1 - Numerical insight into the micromechanics of jet erosion of a cohesive granular material N2 - Here we investigate the physical mechanisms behind the surface erosion of a cohesive granular soil induced by an impinging jet by means of numerical simulations coupling fluid and grains at the microscale. The 2D numerical model combines the Discrete Element and Lattice Boltzmann methods (DEM-LBM) and accounts for the granular cohesion with a contact model featuring a paraboloidal yield surface. Here we review first the hydrodynamical conditions imposed by the fluid jet on a solid granular packing, turning then the attention to the impact of cohesion on the erosion kinetics. Finally, the use of an additional subcritical debonding damage model based on the work of Silvani and co-workers provides a novel insight into the internal solicitation of the cohesive granular sample by the impinging jet. T2 - 8th International Conference on Micromechanics on Granular Media CY - Montpellier, France DA - 03.07.2017 KW - Micromechanical modelling KW - LBM-DEM KW - Jet erosion KW - Granular cohesion KW - Subcritical debonding PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-411186 DO - https://doi.org/10.1051/epjconf/201714015017 VL - 140 SP - Paper 15017, 1 EP - Paper 15017, 4 PB - The European Physical Journal (EPJ) - Web of Conferences AN - OPUS4-41118 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Philippe, P. A1 - Cuéllar, Pablo A1 - Brunier-Coulin, F. A1 - Luu, L.-H. A1 - Benahmed, N. A1 - Bonelli, S. A1 - Delenne, J.-Y. T1 - Physics of soil erosion at the microscale N2 - We focus here on the major and still relevant issue of soil erosion by fluid flows, and more specifically on the determination of both a critical threshold for erosion occurrence and a kinetics that specifies the rate of eroded matter entrainment. A state-of-the-art is first proposed with a critical view on the most commonly used methods and erosion models. It is then discussed an alternative strategy, promoting the use of model materials that allow systematic parametric investigations with the purpose of identifying more precisely the local mechanisms responsible for soil particle erosion and ultimately quantifying both critical onsets and kinetics, possibly through existing or novel empirical erosion laws. Finally, we present and discuss several examples following this methodology, implemented either by means of experiments or numerical simulations, and coupling erosion tests in several particular hydrodynamical configurations with wisely selected mechanical tests. T2 - 8th International Conference on Micromechanics on Granular Media CY - Montpellier, France DA - 03.07.2017 KW - Erosion phenomena KW - Onset of jet erosion KW - LBM-DEM numerical simulation KW - Experimental testing KW - PLIF-RIM optical techniques PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-411198 DO - https://doi.org/10.1051/epjconf/201714008014 VL - 140 SP - Paper 08014, 1 EP - Paper 08014, 4 PB - The European Physical Journal (EPJ) - Web of Conferences AN - OPUS4-41119 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Brunier-Coulin, F. A1 - Sarrat, J.-L. A1 - Cuéllar, Pablo A1 - Philippe, P. T1 - Experimental investigation of impinging jet erosion on model cohesive granular materials N2 - Erosion of soils affects both natural landscapes and engineering constructions as embankment dams or levees. Improving the safety of such earthen structures requires in particular finding out more about the elementary mechanisms involved in soil erosion. Towards this end, an experimental work was undertaken in three steps. First, several model materials were developed, made of grains (mostly glass beads) with solid bridges at particle contacts whose mechanical yield strength can be continuously varied. Furthermore, for most of them, we succeeded in obtaining a translucent system for the purpose of direct visualization. Second, these materials were tested against surface erosion by an impinging jet to determine a critical shear stress and a kinetic coefficient. Note that an adapted device based on optical techniques (combination of Refractive Index Matching and Planar Laser Induced Fluorescence) was used specifically for the transparent media. Third, some specifically developed mechanical tests, and particularly traction tests, were implemented to estimate the mechanical strength of the solid bridges both at micro-scale (single contact) and at macro-scale (sample) and to investigate a supposed relationship with soil resistance to erosion. T2 - 8th International Conference on Micromechanics on Granular Media CY - Montpellier, France DA - 03.07.2017 KW - Erosion onset KW - Experimental testing KW - Cohesive granular media KW - RIM-PLIF techniques PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-411215 DO - https://doi.org/10.1051/epjconf/201714008002 VL - 140 SP - Paper 08002, 1 EP - Paper 08002, 4 PB - The European Physical Journal (EPJ) - Web of Conferences AN - OPUS4-41121 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pfennig, Anja A1 - Kranzmann, Axel A1 - Wolthusen, Helmut T1 - Unusual Corrosion Behavior of 1.4542 Exposed a Laboratory Saline Aquifer Water CCS-Environment N2 - Differently heat treated coupons of 1.4542 were kept at T=60 °C and ambient pressure as well as p=100 bar for 700 h - 8000 h in an a) water saturated supercritical CO2 and b) CO2-saturated synthetic aquifer environment similar to on-shore CCS-sites in the Northern German Basin. Surface corrosion layers are homogeneous but unusually discontinuously ellipsoidal. After 8000 h at 100 bar maximum corrosion rate in the liquid phase is approximately 0.014 mm/year, with normalizing providing best corrosion resistance and approximately 0.003 mm/year in the supercritical phase where hardening+tempering at 670 °C leads to lowest corrosion rates. KW - CO2-storage KW - Supercritical CO2 KW - Steel KW - Pipeline KW - Corrosion KW - CCS PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-418472 DO - https://doi.org/10.1016/j.egypro.2017.03.1679 VL - 114 SP - 5229 EP - 5240 PB - Elsevier Ltd. AN - OPUS4-41847 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -