TY - JOUR A1 - Thiele, Marc A1 - Pirskawetz, Stephan T1 - Analysis of damage evolution in concrete under fatigue loading by acoustic emission and ultrasonic testing N2 - The fatigue process of concrete under compressive cyclic loading is still not completely explored. The corresponding damage processes within the material structure are especially not entirely investigated. The application of acoustic measurement methods enables a better insight into the processes of the fatigue in concrete. Normal strength concrete was investigated under compressive cyclic loading with regard to the fatigue process by using acoustic methods in combination with other nondestructive measurement methods. Acoustic emission and ultrasonic signal measurements were applied together with measurements of strains, elastic modulus, and static strength. It was possible to determine the anisotropic character of the fatigue damage caused by uniaxial loading based on the ultrasonic measurements. Furthermore, it was observed that the fatigue damage seems to consist not exclusively of load parallel oriented crack structures. Rather, crack structures perpendicular to the load as well as local compacting are likely components of the fatigue damage. Additionally, the ultrasonic velocity appears to be a good indicator for fatigue damage beside the elastic modulus. It can be concluded that acoustic methods allow an observation of the fatigue process in concrete and a better understanding, especially in combination with further measurement methods. KW - Concrete KW - Fatigue KW - Damage evolution KW - Ultrasonic testing KW - Acoustic emission PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-541891 DO - https://doi.org/10.3390/ma15010341 SN - 1996-1944 VL - 15 IS - 1 SP - 341 EP - 355 PB - MDPI CY - Basel AN - OPUS4-54189 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lauhoff, Christian A1 - Degener, Sebastian A1 - Bolender, Artjom A1 - Liehr, Alexander A1 - Hübner, Leoni A1 - Frenck, Johanna-Maria A1 - Molotnikov, Andrey A1 - Niendorf, Thomas T1 - In Situ Synchrotron Diffraction Assessment of Reversibility of the Martensitic Transformation in Single-Crystalline Co–Ni–Ga Shape Memory Alloy Under Torsion N2 - AbstractHeusler-type Co–Ni–Ga shape memory alloys attracted significant attention due to their excellent functional properties in single-crystalline state under both compressive and tensile loading. The present study investigates the superelastic deformation behavior under torsion. Using a newly installed torsion testing setup, in situ synchrotron diffraction was carried out on single-crystalline material in order to investigate the martensitic phase transformation. Incremental deformation experiments reveal a fully reversible martensitic transformation under torsional loading at room temperature, leading to excellent strain recovery after deformation to 6.5% shear strain. Furthermore, relevant aspects towards the analysis of powder diffraction data obtained for single-crystalline material in transmission mode under torsional loading are presented and critically discussed. KW - Shape memory alloy KW - Pseudoelasticity KW - Martensitic transformation KW - Synchrotron diffraction KW - In situ testing KW - Torsion PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-621872 DO - https://doi.org/10.1007/s40830-024-00496-8 VL - 10 SP - 326 EP - 333 PB - Springer Science and Business Media LLC AN - OPUS4-62187 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Baeßler, Matthias T1 - Maßgeblicher Einfluss geotechnischer Interaktionsprobleme auf den Tragwerksentwurf: Zwei spezielle Fallbeispiele N2 - Geotechnische Interaktionsprobleme können den Entwurf eines Tragwerks maßgeblich beeinflussen. Anhand zweier Fallbeispiele - dem Schotteroberbau auf Brücken im HGV und der Installation großer Monopiles - werden aktuelle Fälle aus dem Forschungsrepertoire der BAM vorgestellt. T2 - Geotechnische Seminarreihe am IBF des KIT CY - Karlsruhe, Germany DA - 23.01.2025 KW - Schotter auf Brücken im Hochgeschwindigkeitsverkehr KW - Pfahlfussbeulen KW - Beschleunigungsgrenzwert KW - Rammung KW - Monopiles PY - 2025 AN - OPUS4-62451 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Simon, Patrick T1 - Experimente in der Klimakammer N2 - Im Rahmen des Verbundtreffens des Vorhabens AISTEC werden akutelle Versuche aus der Großklimakammer des FB 7.2 präsentiert. T2 - 5. Verbundtreffen AISTEC CY - Online meeting DA - 24.06.2021 KW - Klimakammer KW - Stochastic Subspace Damage Detection KW - Model Update KW - Asphalt PY - 2021 AN - OPUS4-52869 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Baeßler, Matthias T1 - OWEC repowering from a structural engineering and research perspective N2 - A significant number of new wind farms has to be installed and, at the same time, existing wind farms reaching the end of their planned life need to be reused efficiently to ensure that the ambitous goals for deploying offshore wind are met. Some relevant reuse alternatives for offshore wind farms are lifetime extension, repowering utilizing existing substructures and full replacement. In this presentation - starting from experience gained from extending the lifetime of the of the U1 metro viaduct in Berlin - we discuss end-of-life decision making in offshore wind. We focus particularly on issues concerning substructures and highlight existing challenges and opprtunities in research and development. T2 - RWE RePowering Event CY - Wilhelmshaven, Germany DA - 10.10.2023 KW - Offshore wind KW - End-of-life decision making KW - Repowering KW - Substructures PY - 2023 AN - OPUS4-58632 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Simon, Patrick T1 - Enhancing structural models with material tests and static response data - a case study considering a steel beam with asphalt layer subject to temperature variations N2 - Gradual or sudden changes in the state of structural systems caused, for example, by deterioration or accidental load events can influence their load-bearing capacity. Structural changes can be inferred from static and/or dynamic response data measured by structural health monitoring systems. However, they may be masked by variations in the structural response due to varying environmental conditions. Particularly, the interaction of nominally load-bearing components with nominally non-load bearing components exhibiting characteristics that vary as a function of the environmental conditions can significantly affect the monitored structural response. Ignoring these effects may hamper an inference of structural changes from the monitoring data. To address this issue, we adopt a probabilistic model-based framework as a basis for developing digital twins of structural systems that enable a prediction of the structural behavior under varying ambient condition. Within this framework, different types of data obtained from real the structural system can be applied to update the digital twin of the structural system using Bayesian methods and thus enhance predictions of the structural behavior. In this contribution, we implement the framework to develop a digital twin of a simply supported steel beam with an asphalt layer. It is formulated such that it can predict the static response of the beam in function of its temperature. In a climate chamber, the beam was subject to varying temperatures and its static response wass monitored. In addition, tests are performed to determine the temperature-dependent properties of the asphalt material. Bayesian system identification is applied to enhance the predictive capabilities of the digital twin based on the observed data. T2 - International Conference on Structural Health Monitoring of Intelligent Infrastructure (SHMII-10) CY - Online meeting DA - 30.06.2021 KW - Digital twin KW - Structural health monitoring KW - Material tests KW - Bayesian updating PY - 2021 AN - OPUS4-54130 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Baeßler, Matthias A1 - Herrmann, Ralf A1 - Hille, Falk A1 - Wille, Frank T1 - Dynamisches Verhalten und Überwachung des Großen Fallturms der BAM in Horstwalde N2 - Falltürme sind Bauwerke, die als Versuchsanlagen sehr speziellen, impulsartigen Belastungen ausgesetzt sind. Am Fallturm auf dem Testgelände Technische Sicherheit (TTS) der BAM wurde bei Routineinspektionen eine Abnahme der strukturellen Integrität in Form von Vorspannungsverlusten in den Bolzen der Stahlverbindungen festgestellt. Um ein Verständnis für die zugrundeliegenden Trag- und Schädigungsmechanismen zu erlangen, wurde ein umfassendes Structural Health Monitoring (SHM) System geplant und am Bauwerk installiert unter Nutzung von digitalen Bauwerksmodellen. Für die Auslegung des Überwachungssystems, insbesondere aber zur Unterstützung der Untersuchung des Schädigungsprozesses, wurden Finite-Elemente-Modelle erstellt. Um sicherzustellen, dass die FE-Modelle das reale Tragwerksverhalten mit ausreichender Genauigkeit abbilden, mussten sie jedoch in Bezug auf die gemessenen Antworten des Tragwerks kalibriert werden. Der vorliegende Beitrag beschreibt experimentelle und numerische Untersuchungen zur Identifizierung des strukturellen Systems des Stahlrohrgitterturms in Vorbereitung einer Überwachungskampagne. Die Auswertung von gemessenen Schwingungen unter ambienter Anregung ermöglichte die Identifizierung der Eigenfrequenzen mehrerer globaler Schwingungsmoden des Fallturms. Zur Modellvalidierung wurde zunächst eine Sensitivitätsanalyse durchgeführt, um die Parameter mit dem größten Einfluss zu ermitteln. Anschließend wurde ein evolutionärer Algorithmus (EA) zur Optimierung nach dem Prinzip der Minimierung der Differenzen zwischen gemessenen und simulierten charakteristischen Antworten eingesetzt. Das aktualisierte Modell wurde schließlich an der dynamischen Reaktion der Turmstruktur infolge einer realen Falltest-induzierten Stoßbelastung validiert. Die Ergebnisse zeigten eine gute Übereinstimmung zwischen numerischen und experimentellen Ergebnissen. N2 - Drop test towers are structures subjected to very specific dynamic loadings. At the drop test tower at the Test Site Technical Safety (TTS) of BAM routine inspections revealed a decline of structural integrity in form of loss of pretension in bolts of structural steel connections. To get an understanding about the underlying damage mechanisms as well as to assure the structural safety in operation, a multifaceted Structural Health Monitoring (SHM) system was planned and installed at the structure with the help of digital models. For planning the monitoring system but especially for supporting the investigation of the damaging process finite element models are deployed. Though, to ensure the capability of the FE model to reproduce the real structural behavior in sufficient accuracy, it needs to be calibrated in respect to measured responses of the structure. The present contribution describes experimental and numerical investigations to identify the structural system of the steel tube lattice tower in preparation of the monitoring campaign. An ambient vibration test allowed the identification of the natural frequencies of several global vibrational modes of the drop test tower. For model updating first a sensitivity analysis is applied to identify the most influencing parameter. In succession a genetic algorithm was applied for optimization in the sense of minimization of the difference between measured and simulated characteristic responses. The updated model is finally validated on the dynamic response of the tower structure to a real drop test induced impact loading. The results showed a good agreement between numerical and experimental results though the robustness of the simulation should be improved by more sophisticated numerical modelling. T2 - 7. VDI-Fachtagung Baudynamik CY - Würzburg, Germany DA - 27.04.2022 KW - Großer Fallturm Horstwalde KW - Structural Health Monitoring KW - Belastungsversuch KW - Modalanalyse KW - Schwingungsdynamik KW - Finite Elemente Simulation PY - 2022 SN - 978-3-18-092379-6 SN - 978-3-18-102379-2 DO - https://doi.org/10.51202/9783181023792-265 SN - 0083-5560 VL - 2379 SP - 265 EP - 284 PB - VDI-Verlag CY - Düsseldorf AN - OPUS4-55472 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Suffa, Philipp A1 - Kemmler, Samuel A1 - Koestler, Harald A1 - Ruede, Ulrich T1 - Large-scale simulations of fully resolved complex moving geometries with partially saturated cells N2 - We employ the Partially Saturated Cells Method to model the interaction between the fluid flow and solid moving objects as an extension to the conventional lattice Boltzmann method. We introduce an efficient and accurate method for mapping complex moving geometries onto uniform Cartesian grids suitable for massively parallel processing. A validation of the physical accuracy of the solid–fluid coupling and the proposed mapping of complex geometries is presented. The implementation is integrated into the code generation pipeline of the waLBerla framework so that highly optimized kernels for Central Processing Unit (CPU) and Graphical Processing Unit (GPU) architectures become available. We study the node-level performance of the automatically generated solver routines. 71% of the theoretical peak performance can be achieved on CPU nodes and 86% on GPU accelerated nodes. Only a moderate overhead is observed for the processing of the solid–fluid coupling when compared to the fluids simulations without moving objects. Finally, a counter-rotating open rotor is presented as a prototype industrial scenario, resulting in a mesh size involving up to 4.3 × 109 fluid grid cells. For this scenario, excellent parallel efficiency is reported in a strong scaling study on up to 32 768 CPU cores on the LUMI-C supercomputer and on up to 1024 NVIDIA A100 GPUs on the JUWELS Booster system. KW - Computational fluid dynamics KW - Lattice Boltzmann methods KW - Fluid coupling KW - Turbulent flows KW - Supercomputer PY - 2025 DO - https://doi.org/10.1063/5.0268021 SN - 1070-6631 VL - 37 IS - 5 SP - 1 EP - 13 PB - AIP Publishing AN - OPUS4-63188 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wiehle, Philipp A1 - Härder, M. A1 - Strangfeld, Christoph T1 - Feuchteverhalten von Lehmsteinmauerwerk unter natürlichen Klimabedingungen – Experimentelle und numerische Untersuchungen N2 - Druckfestigkeit und Elastizitätsmodul von Lehmsteinmauerwerk nehmen mit steigendem Feuchtegehalt ab, weswegen die Mauerwerksdruckfestigkeit bei der Bemessung gemäß DIN 18940 in Abhängigkeit der maximal zu erwartenden Ausgleichsfeuchte abgemindert wird. Da bisher allerdings keine Messdaten zum Feuchtegehalt von Lehmsteinmauerwerk unter natürlichen Klimabedingungen vorliegen, stellen die normativen Grenzwerte lediglich eine konservative Abschätzung dar. Um die Feuchtegehalte von Lehmsteinmauerwerk und somit die Tragfähigkeit realitätsnah einschätzen zu können, wurden im Rahmen der vorliegenden Arbeit sowohl experimentelle als auch numerische Untersuchungen zum feuchtetechnischen Verhalten durchgeführt. Dabei wurden erstmalig magnetresonanzspektroskopische Untersuchungen an tragenden Lehmsteinen unterschiedlicher Herstellungsmethoden angewandt Weiterhin wurden Luftfeuchtesensoren in Lehmsteinmauerwerk eingebettet, um hygrische Langzeitfeuchtemessungen unter natürlichen Klimabedingungen durchzuführen. Auf Basis dieser Erkenntnisse wurde schließlich ein numerisches Modell kalibriert und Parameterstudien durchgeführt, um den unter realen Klimabedingungen tatsächlich auftretenden Feuchtegehalt im Lehmmauerwerk sowie dessen Verteilung über den Querschnitt einschätzen zu können und die normativen Grenzwerte zu überprüfen. Gezeigt wurde, dass die realitätsnahe instationäre Berechnung des Feuchtetransports mit üblichen hygrothermischen Simulationsprogrammen auf Basis einfacher feuchtetechnischer Kennwerte auch bei Lehmbaustoffen möglich ist. Der Einfluss des Quellens und Schwindens der enthaltenen Tonminerale und organischen Bestandteile wurde durch eine Modifikation bei der Ermittlung des Wasseraufnahmekoeffizienten explizit berücksichtigt und ist somit auch in den daraus abgeleiteten Transportkoeffizienten enthalten. Darüber hinaus wurde die Feuchtespeicherfunktion im überhygroskopischen Bereich auf Grundlage der Porenvolumenverteilung abgeschätzt. Die Approximation der Transportkoeffizienten und der Feuchtespeicherfunktion stellt dabei eine wesentliche Vereinfachung für Lehmbaustoffe dar, da ihre experimentelle Bestimmung aufgrund des Kontaktes mit Flüssigwasser kaum möglich ist. In Bezug auf das Feuchteverhalten üblicher Außenwandaufbauten von Wohnräumen konnte festgestellt werden, dass die Ausgleichsfeuchte im Lehmsteinmauerwerk stets unterhalb des in Nutzungsklasse 1 gemäß DIN 18940 zulässigen Grenzwertes von 65 % liegt. Je nach Putzsystem und Dämmstoff reduziert sich die Ausgleichsfeuchte auf Werte unter 60 %, wobei sich eine annähernd gleichmäßige Verteilung der Feuchte über den Mauerwerksquerschnitt hinweg einstellt. Bei Außenwänden von unbeheizten Räumen ergab sich eine maximale Ausgleichsfeuchte, die über weite Teile des Querschnitts unterhalb von 80 % lag. Der Ansatz einer maximalen Ausgleichsfeuchte von 90 % in Nutzungsklasse 2 ist folglich zu hoch angesetzt. Die zulässige Ausgleichsfeuchte bzw. der Umgebungsfeuchtefaktor in Nutzungsklasse 2 sollte dementsprechend angepasst werden T2 - LEHM 2024 – 9. Internationale Fachtagung für Lehmbau CY - Weimar, Germany DA - 27.09.2024 KW - Lehmstein KW - Mauerwerk KW - Materialfeuchte KW - Feuchtemonitoring KW - hygrothermische Simulation PY - 2024 SP - 1 EP - 10 AN - OPUS4-61217 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Simon, Patrick T1 - Zustandsbewertung von Bauwerken unter veränderlichen Umgebungsbedingungen mittels Structural Health Monitoring N2 - Brücken sind Teil der alternden Verkehrsinfrastruktur. Um die Nutzungsdauer zu verlängern und plötzliche Schäden zu detektieren kann Bauwerksmonitoring ("Structural Health Monitoring") eingesetzt werden. Der Einfluss von Umgebungsbedingungen, beispielsweise der Temperatur, auf das Bauwerksverhalten ist meist größer als der Einfluss von Schäden. Diese Einflüsse bestmöglich voneinander zu trennen und Veränderungen im Tragverhalten korrekt Schäden oder Umgebungsbedingungen zuzuordnen ist eine offene Forschungsfrage. Diese Arbeit zeigt eine mögliche Lösung, bei der gekoppelte Modelle von Umwelteinflüssen, Schäden und Tragverhalten des Bauwerks auf Grundlage von Monitoringdaten aktualisiert werden. Das Framework dazu wird vorgestellt und an einem Laborexperiment eines Stahlbetonbalkens in der Klimakammer angewandt. Die Ergebnisse bestätigen die Vorgehensweise. In nächsten Schritten müssen komplexere Tragwerke und die Sensitivität des Ansatzes untersucht werden. T2 - Forschungskolloquium, Institut für Konstruktiven Ingenieurbau, Bauhaus-Universität Weimar CY - Weimar, Germany DA - 28.06.2023 KW - Structural health monitoring KW - Bauwerksmonitoring KW - Umwelteinflüsse KW - Brücken PY - 2023 AN - OPUS4-58005 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Brinkmann, M. A1 - Wiehle, Philipp A1 - Thiele, Marc A1 - Graubner, C.-A. ED - Schermer, D. ED - Brehm, E. T1 - Grundlagen zur Bemessung druckbeanspruchten Lehmmauerwerks N2 - Lehmmauerwerk bietet sich aufgrund seiner zahlreichen ökologischen Vorteile für die Errichtung klimafreundlicher und ressourcenschonender Gebäude an. Um den Anwendungsbereich tragenden Lehmmauerwerks durch eine zeitgemäße Nachweisführung zu erweitern, werden in diesem Beitrag Grundlagen für die Entwicklung eines eurocodekonformen Bemessungskonzepts erarbeitet. Hierzu werden die Ergebnisse umfangreicher experimenteller Untersuchungen an Lehmmauerwerk sowie Lehmsteinen und -mörteln nach Konditionierung bei unterschiedlichen Klimata vorgestellt. Darauf aufbauend erfolgt eine Traglastanalyse druckbeanspruchter Lehmmauerwerkswände mittels numerischer und analytischer Methoden. Die daraus gewonnenen Erkenntnisse werden abschließend in einen an DIN~EN~1996-3/NA angelehnten Bemessungsvorschlag überführt, welcher die materialspezifischen Besonderheiten von Lehmmauerwerk berücksichtigt und eine fundierte Grundlage für eine wirtschaftliche und zuverlässige Nachweisführung darstellt. KW - Druckfestigkeit KW - Lehm KW - Mauerwerk KW - Bemessung KW - Feuchte PY - 2023 SN - 978-3-433-03373-9 DO - https://doi.org/10.1002/9783433611142.ch4 VL - 48 SP - 79 EP - 110 PB - Ernst & Sohn GmbH CY - Berlin ET - 1 AN - OPUS4-57509 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hering, Marcus A1 - Sievers, Jürgen A1 - Curbach, Manfred A1 - Beckmann, Birgit T1 - An Approach to Predicting the Ballistic Limit of Thin Textile-Reinforced Concrete Plates Based on Experimental Results N2 - In this article, a partial selection of experiments on enhancing the impact resistance of structural components with non-metallic, textile-reinforced concrete is discussed. The focus is on the experimental investigations in which the impact resistance of thin, textile-reinforced concrete plates is characterized. The article discusses the materials, fabrics and test setup used. For the experimental work, a drop tower from the Otto Mohr Laboratory, which belongs to the Technische Universtät Dresden, was used. Furthermore, the experimental results are presented and evaluated using different methods. Based on the collected data, a suitable approach to determining the perforation velocity of an impactor through the investigated thin, textile-reinforced concrete plates is shown. KW - Building and Construction KW - Civil and Structural Engineering PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-586692 DO - https://doi.org/10.3390/buildings13092234 VL - 13 IS - 9 SP - 1 EP - 14 PB - MDPI AN - OPUS4-58669 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ratkovac, Mirjana A1 - Gerards-Wünsche, Paul A1 - Thiele, Marc A1 - Brackrock, Daniel A1 - Stamm, Michael T1 - Detection and monitoring of the fatigue crack growth on welds – Application-oriented use of NDT methods N2 - Early detection of fatigue cracks and accurate measurements of the crack growth play an important role in the maintenance and repair strategies of steel structures exposed to cyclic loads during their service life. Observation of welded connections is especially of high relevance due to their higher susceptibility to fatigue damage. The aim of this contribution was to monitor fatigue crack growth in thick welded specimens during fatigue tests as holistically as possible, by implementing multiple NDT methods simultaneously in order to record the crack initiation and propagation until the final fracture. In addition to well-known methods such as strain gauges, thermography, and ultrasound, the crack luminescence method developed at the Bundesanstalt für Materialforschung und -prüfung (BAM), which makes cracks on the surface particularly visible, was also used. For data acquisition, a first data fusion concept was developed and applied in order to synchronize the data of the different methods and to evaluate them to a large extent automatically. The resulting database can ultimately also be used to access, view, and analyze the experimental data for various NDT methods. During the conducted fatigue tests, the simultaneous measurements of the same cracking process enabled a comprehensive comparison of the methods, highlighting their individual strengths and limitations. More importantly, they showed how a synergetic combination of different NDT methods can be beneficial for implementation in large-scale fatigue testing but also in monitoring and inspection programs of in-service structures - such as the support structures of offshore wind turbines. T2 - Fatigue Design 2023 (FatDes 2023) CY - Senlis, France DA - 29.11.2023 KW - Fatigue KW - Welded KW - NDT KW - Crack growth PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-600238 DO - https://doi.org/10.1016/j.prostr.2024.03.062 VL - 57 SP - 560 EP - 568 PB - Elsevier B.V. AN - OPUS4-60023 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Eichner, Lukas A1 - Schneider, Ronald A1 - Baeßler, Matthias T1 - Optimal vibration sensor placement for jacket support structures of offshore wind turbines based on value of information analysis N2 - Information on the condition and reliability of an offshore jacket structure provided by a vibration-based structural health monitoring system can guide decisions on inspection and maintenance. When selecting the sensor setup, the designer of the monitoring system must assess its overall benefit compared to its costs before installation. The potential benefit of continuously monitoring the dynamic response of a jacket structure can be formally quantified through a value of information analysis from Bayesian decision theory. In this contribution, we present a framework for optimizing the placement of vibration sensors on offshore jacket structures by maximizing the value of information of the monitoring system. To solve the resulting discrete optimization problem, we adapt a genetic algorithm. The framework is demonstrated in a numerical example considering a redundant jacket-type steel frame. The numerical study shows that monitoring the vibration response of the frame is beneficial. Good sensor setups consist of relatively few sensors located towards the upper part of the frame. The adapted genetic algorithm performs similarly well as established sequential sensor placement algorithms and holds substantial promise for application to real jacket structures. KW - Optimal sensor placement KW - Value of information KW - Jacket support structure KW - Offshore wind turbine KW - Monitoring-informed inspection and maintenance planning PY - 2023 DO - https://doi.org/10.1016/j.oceaneng.2023.115407 SN - 0029-8018 VL - 288 IS - 2 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-58725 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Artinov, Antoni T1 - Modeling the Relationship between Weld Pool Dynamics and Centerline Solidification Cracking in High Power Laser Beam Welding N2 - The present work deals with the recently confirmed widening of the weld pool interface, known as a bulging effect, and its relevance in high power laser beam welding. A combined experimental and numerical approach is utilized to study the influence of the bulge on the hot cracking formation and the transport of alloying elements in the molten pool. A technique using a quartz glass, a direct-diode laser illumination, a high-speed camera, and two thermal imaging cameras is applied to visualize the weld pool geometry in the longitudinal section. The study examines the relevance of the bulging effect on both, partial and complete penetration, as well as for different sheet thicknesses ranging from 8 mm to 25 mm. The numerical analysis shows that the formation of a bulge region is highly dependent on the penetration depth and occurs above 10 mm penetration depth. The location of the bulge correlates strongly with the cracking location. The obtained experimental and numerical results reveal that the bulging effect increases the hot cracking susceptibility and limits the transfer of alloying elements from the top of the weld pool to the weld root. T2 - Gastvortrag an der Universität Innsbruck, Institut für Konstruktion und Materialwissenschaften CY - Innsbruck, Austria DA - 18.06.2023 KW - Laser beam welding KW - Centerline solidification cracking KW - Bulging KW - Numerical simulation PY - 2024 AN - OPUS4-60333 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Frenck, Johanna-Maria A1 - Frenck, Georg A1 - Degener, Sebastian A1 - Vollmer, Malte A1 - Niendorf, Thomas T1 - Interrelationships of stress-induced martensitic phase transformation and pitting corrosion in iron-based shape memory alloys N2 - Orientation dependence of stress-induced martensitic transformation under compression and the influence of a corrosion attack on superelastic properties were investigated for Fe42.7Mn34.7Al13.4Ni7.7Cr1.5 (at.−%) single crystals. The results of incremental strain tests show that the crystallographic orientation has a considerable impact on the superelastic performance, eventually resulting from the formation of twinned or detwinned martensite to accommodate strain as well martensite variant interaction. In order to investigate the effect of a corrosive environment on the mechanical performance and martensitic transformation, compression specimens were immersed in a 5.0 wt.−% NaCl solution for 24 h before tested in incremental strain tests. The immersion of the compression specimens revealed a partial surface corrosion attack including localized pitting corrosion. The localized corrosion attack increased the number of active martensite plates, most probably due to an induced multiaxial stress state. Further investigations on specimens subjected to −6% compressive strain revealed that areas with retransformed martensite serve as nucleation zones for corrosion damage. Stress-induced corrosion cracks developed, which eventually deteriorate functional response. KW - Shape memory alloy (SMA) KW - In situ characterization KW - Corrosion KW - Austenite-to-martensite phase transformation PY - 2024 DO - https://doi.org/10.1016/j.mtla.2023.102001 VL - 33 SP - 1 EP - 11 PB - Elsevier BV AN - OPUS4-61283 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Simon, Patrick T1 - Bayesian system identification of a reinforced concrete beam subject to temperature variations based on static response data N2 - Changes in the measured response of structural systems can be an indication of structural damages. However, such changes can also be caused by the effect of varying environmental conditions. To detect, localize and quantify changes or damages in structural systems subject to varying environmental conditions, physics-based models of the structural systems have to be applied which explicitly account for the influence of ambient conditions on the structural behavior. Data obtained from the structural systems should be used to calibrate the models and update predictions. Bayesian system identification is an effective framework for this task. In this paper, we apply this framework to learn the parameters of two competing structural models of a reinforced concrete beam subject to varying temperatures based on static response data. The models describe the behavior of the beam in the uncracked and cracked condition. The data is collected in a series of load tests in a climate chamber. Bayesian model class selection is then applied to infer the most plausible condition of the beam conditional on the available data. T2 - Tenth International Conference on Bridge Maintenance, Safety and Management (IABMAS 2020) CY - Online meeting DA - 11.04.2021 KW - Bayesian system identification KW - Reinforced concrete KW - Damage identification KW - Environmental effects KW - Structural health monitoring KW - Structural systems PY - 2021 AN - OPUS4-52812 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Baeßler, Matthias T1 - Recap: Main Results of the BUMP Study and Relevance for VERBATIM N2 - Zusammenfassung des Forschungsprojekts BUMP hinsichtlich der Relevanz für das Projekt VERBATIM N2 - BUMP had been a theoretical prestudy on open issues for the pile tip buckling of large monopiles. The presentation summarizes the main results and considers the impact for the ongoing VERBATIM project. VERBATIM is set up as a mainly experimental verification project for pile buckling. T2 - Kick-Off Projekt VERBATIM CY - BAM, Berlin, Germany DA - 23.01.2020 KW - Buckling piles circular shells PY - 2020 AN - OPUS4-50515 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Herrmann, Ralf A1 - Hille, Falk A1 - Said, Samir A1 - Sterthaus, Jens A1 - Müller, Karsten A1 - Quercetti, Thomas A1 - Wille, Frank A1 - Paffenholz, J.-A. A1 - Baeßler, Matthias ED - Papadrakakis, M. ED - Fragiadakis, M. ED - Papadimitriou, C. T1 - Implementing a Structural Health Monitoring system using digital models of the BAM large drop test facility in Horstwalde N2 - At the Bundesanstalt für Materialforschung und -prüfung (BAM) full scale specimens for nuclear transport and storage containers (casks) are tested for their structural integrity in a series of drop tests on the Test Site Technical Safety in Horstwalde, 50 km south of Berlin. These drop tests cause a major stress not only on the casks, but also on the steel tower structure of the test facility, itself. The load pattern makes the structure very interesting for detailed investigation. The focus of the monitoring lies on the bolted joints of the flange connections that are a typical connection for cylindrical elements if welding is technical or economical unfavorable. The definition of the monitoring takes was done by investigating the existing documents and inspection results accompanied by building an initial digital representation of the structure, consisting of two finite element (FE) models and a geometrical 3D point cloud representation. As a first step the structures behavior during static and dynamic loading was analyzed using measurement data and an updated numerical FE Model. The idea behind is to use models for a digital planning and operation/evaluation of the structural health monitoring. A static FE simulation and a dynamic FE simulation are generated, to investigate how the structure behaves under the load conditions. T2 - XI International Conference on Structural Dynamics (EuroDyn 2020) CY - Online meeting DA - 23.11.2020 KW - Structural Health Monitoring KW - Drop Tests KW - System Identification KW - Digital Models KW - BIM PY - 2020 UR - https://generalconferencefiles.s3-eu-west-1.amazonaws.com/eurodyn_2020_ebook_procedings_vol1.pdf SN - 978-618-85072-0-3 VL - 1 SP - 1293 EP - 1304 PB - Institute of Structural Analysis and Antiseismic Research CY - Athen AN - OPUS4-51592 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Herrmann, Ralf T1 - Digitalisierung sichert die Bauwerke von gestern und das Wissen von morgen N2 - Die moderne Gesellschaft in Deutschland und Europa profitiert von der hervorragenden baulichen Infrastruktur, die für uns viele Aspekte aus den Bereichen Mobilität, Energieversorgung, Transport, Umweltschutz, (Nah-)Erholung und Gefahrenabwehr zur Alltäglichkeit werden lassen und uns ein hohes Gefühl der technischen Sicherheit vermitteln. Viele der Annehmlichkeiten, wie beispielweise ein Hochgeschwindigkeitseisenbahnverkehrsnetz, zuverlässige Stromversorgung im europäischen Verbundsystem und ein immenser Personen-, Güter- und Warenverkehr auf der Straße, zu Wasser und in der Luft ist ohne eine leistungsfähige, resiliente und zuverlässige bauliche Infrastruktur undenkbar. KW - Bauwerksmonitoring KW - Bauwerksdiagnostik KW - Digitalisierung PY - 2022 DO - https://doi.org/10.1002/bate.202270303 SN - 1437-0999 SN - 0932-8351 VL - 99 IS - 3 SP - 161 EP - 162 PB - Ernst & Sohn GmbH CY - Berlin AN - OPUS4-54557 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -