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  <doc>
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    <completedYear/>
    <publishedYear>2023</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
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    <pageLast/>
    <pageNumber/>
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    <publisherName>Zenodo</publisherName>
    <publisherPlace>Geneva</publisherPlace>
    <creatingCorporation>Bundesanstalt für Materialforschung und -prüfung (BAM)</creatingCorporation>
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    <title language="eng">Efficient bead-on-plate weld model for parameter estimation towards effective wire arc additive manufacturing simulation</title>
    <abstract language="eng">Despite the advances in hardware and software techniques, standard numerical methods fail in providing real-time simulations, especially for complex processes such as additive manufacturing applications. A real-time simulation enables process control through the combination of process monitoring and automated feedback, which increases the flexibil- ity and quality of a process. Typically, before producing a whole additive manufacturing structure, a simplified experiment in form of a bead-on- plate experiment is performed to get a first insight into the process and to set parameters suitably. In this work, a reduced order model for the transient thermal problem of the bead-on-plate weld simulation is devel- oped, allowing an efficient model calibration and control of the process. The proposed approach applies the proper generalized decomposition (PGD) method, a popular model order reduction technique, to decrease the computational effort of each model evaluation required multiple times in parameter estimation, control and optimization. The welding torch is modeled by a moving heat source, which leads to difficulties separating space and time, a key ingredient in PGD simulations. A novel approach for separating space and time is applied and extended to 3D problems allowing the derivation of an efficient separated representation of the tem- perature. The results are verified against a standard finite element model showing excellent agreement. The reduced order model is also leveraged in a Bayesian model parameter estimation setup, speeding up calibrations and ultimately leading to an optimized real-time simulation approach for welding experiment using synthetic as well as real measurement data.</abstract>
    <identifier type="doi">10.5281/zenodo.7456813</identifier>
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    <enrichment key="ScientificDateCreatedStart">19.12.2022</enrichment>
    <enrichment key="ScientificDateCreatedEnd">31.12.2023</enrichment>
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    <licence>Creative Commons - CC BY - Namensnennung 4.0 International</licence>
    <author>Dominic Strobl</author>
    <author>Jörg F. Unger</author>
    <author>G. Chady</author>
    <author>Alexander Klawoon</author>
    <author>Andreas Pittner</author>
    <author>Michael Rethmeier</author>
    <author>Annika Robens-Radermacher</author>
    <subject>
      <language>deu</language>
      <type>uncontrolled</type>
      <value>Ermüdung</value>
    </subject>
    <collection role="ddc" number="620">Ingenieurwissenschaften und zugeordnete Tätigkeiten</collection>
    <collection role="institutes" number="">7 Bauwerkssicherheit</collection>
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    <collection role="fulltextaccess" number="">Datei für die Öffentlichkeit verfügbar ("Open Access")</collection>
    <collection role="literaturgattung" number="">Graue Literatur</collection>
    <collection role="institutes" number="">7.7 Modellierung und Simulation</collection>
    <collection role="unnumberedseries" number="">Forschungsdatensätze der BAM</collection>
    <collection role="themenfelder" number="">Additive Fertigung</collection>
  </doc>
  <doc>
    <id>64352</id>
    <completedYear/>
    <publishedYear>2025</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
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    <title language="eng">Development of a platform for benchmarking of simulation models for verification and validation</title>
    <abstract language="eng">This presentation introduces a modular and open platform developed by BAM for the verification and validation (V&amp;V) of simulation models, particularly material models used across various solvers. The platform aims to enhance transparency, reproducibility, and comparability in computational engineering by integrating standardized workflows, benchmark datasets, and semantic technologies. &#13;
&#13;
Key components include:&#13;
&#13;
Simulation workflows powered by tools like Snakemake and JupyterHub,&#13;
Research Object Crates (ROCrates) for structured data and provenance tracking,&#13;
Ontologies and knowledge graphs to semantically describe models, data, and results,&#13;
Federated registries for storing and querying benchmark results and ROCrates.&#13;
&#13;
The platform supports both verification (e.g., analytical comparisons, convergence studies) and validation (e.g., experimental data matching), and facilitates tool-independent performance metrics using standardized output formats. It promotes collaborative development through containerized environments, automated testing, and reproducible research practices.&#13;
This initiative contributes to the broader goal of ensuring safety in technology and chemistry, aligning with BAM’s mission and supporting the scientific community in developing reliable simulation models.</abstract>
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    <enrichment key="eventPlace">Prague, Czech Republic</enrichment>
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    <author>Jörg F. Unger</author>
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      <language>eng</language>
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      <value>Verification and validation</value>
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    <subject>
      <language>eng</language>
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      <value>Simulation Workflows</value>
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    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Digital Twin</value>
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    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Model Calibration</value>
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    <collection role="institutes" number="">7 Bauwerkssicherheit</collection>
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    <collection role="institutes" number="">7.7 Modellierung und Simulation</collection>
    <collection role="themenfelder" number="">Green Intelligent Building</collection>
  </doc>
  <doc>
    <id>65413</id>
    <completedYear/>
    <publishedYear>2026</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>1</pageFirst>
    <pageLast>20</pageLast>
    <pageNumber/>
    <edition/>
    <issue>2</issue>
    <volume>59</volume>
    <type>article</type>
    <publisherName>Springer Science and Business Media LLC</publisherName>
    <publisherPlace/>
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    <title language="eng">Characterization of temperature influence on the structural build-up of 3D printed concrete</title>
    <abstract language="eng">3D concrete printing technologies enhance design freedom while reducing material use and costs without the need for formwork. Thereby, structural build-up is the key property governing stability and early strength evolution of 3D printed concrete after placement. Structural build-up is influenced by various factors, i.e., environmental conditions such as temperature. In this paper, the influence of ambient temperature on structural build-up was investigated through experimental and numerical approaches. Three experimental setups (small amplitude oscillatory shear, constant shear rate, and small amplitude oscillatory extensional tests) were applied to materials of increasing complexity under varying temperature conditions. A common modeling framework based on the maturity approach was developed to capture the time and temperature evolution. A stochastic framework was employed to estimate the unknown model parameters using experimental data. Experimental results demonstrate a significant temperature influence on structural build-up, consistent across all test setups and materials. The calibrated models successfully predict the structural build-up under different temperatures, confirming the applicability of the maturity approach to rheological parameters at early age. Furthermore, the stochastic parameter estimation allows a correct quantification of the uncertainties, enhancing model reliability. The comparison of two time evolution formulations indicates that a model with an additional linear stage is required for predicting the increase of the storage moduli (&#13;
 &#13;
 &#13;
 $${G}{\prime}$$&#13;
 &#13;
 &#13;
 G&#13;
 ′&#13;
 &#13;
 &#13;
 &#13;
 &#13;
 ,&#13;
 &#13;
 &#13;
 $${E}{\prime}$$&#13;
 &#13;
 &#13;
 E&#13;
 ′&#13;
 &#13;
 &#13;
 &#13;
 &#13;
 ). In conclusion, the study demonstrates that temperature significantly affects the structural build-up, and that the proposed modeling approach allows to predict this behavior.</abstract>
    <parentTitle language="eng">Materials and Structures</parentTitle>
    <identifier type="issn">1359-5997</identifier>
    <identifier type="doi">10.1617/s11527-025-02931-3</identifier>
    <identifier type="urn">urn:nbn:de:kobv:b43-654138</identifier>
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    <enrichment key="RelatedIdentifier">https://doi.org/10.5281/zenodo.15845819</enrichment>
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    <enrichment key="date_peer_review">02.02.2026</enrichment>
    <licence>Creative Commons - CC BY - Namensnennung 4.0 International</licence>
    <author>Annika Robens-Radermacher</author>
    <author>Wolfram Schmidt</author>
    <author>Jörg F. Unger</author>
    <author>Alexander Mezhov</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Structural build-up</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>3D concrete printing</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Rheology</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Temperature influence</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Modeling</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Green intelligent building</value>
    </subject>
    <collection role="ddc" number="624">Ingenieurbau</collection>
    <collection role="institutes" number="">7 Bauwerkssicherheit</collection>
    <collection role="institutes" number="">7.4 Baustofftechnologie</collection>
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    <collection role="institutes" number="">7.7 Modellierung und Simulation</collection>
    <collection role="themenfelder" number="">Green Intelligent Building</collection>
    <thesisPublisher>Bundesanstalt für Materialforschung und -prüfung (BAM)</thesisPublisher>
    <file>https://opus4.kobv.de/opus4-bam/files/65413/Robens-RadermacherEtEl2026_CharacterizationOfTemperatureInfluenceOnStructuralBuild-upOf3DCP.pdf</file>
  </doc>
  <doc>
    <id>58217</id>
    <completedYear/>
    <publishedYear>2023</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>1193</pageFirst>
    <pageLast>1200</pageLast>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume>1st Edition</volume>
    <type>conferenceobject</type>
    <publisherName>CRC Press</publisherName>
    <publisherPlace/>
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    <title language="eng">Temperature dependent modelling approach for early age behavior of printable mortars</title>
    <abstract language="eng">Structural build-up describes the stability and early-age strength development of fresh mortar used in 3D printing. lt is influenced by several factors, i.e. the composition of the print­ able material, the printing regime, and the ambient conditions. The existing modelling approaches for structural build-up usually define the model parameters for a specific material composition with­ out considering the influence of the ambient conditions. The goal of this contribution is to explicitly include the temperature dependency in the modelling approach. Temperature changes have signifi­ cant impact on the structural build-up process: an increase of the temperature leads to a faster dissol­ ution of cement phases and accelerates hydration. The proposed extended model includes temperature dependency using the Arrhenius theory. The new model parameters are successfully calibrated based on Viskomat measurement data using Bayesian inference. Furthermore, a higher impact of the temperature in the re-flocculation as in the structuration stage is observed.</abstract>
    <parentTitle language="eng">Life-Cycle of Structures and Infrastructure Systems</parentTitle>
    <identifier type="issn">978-1-003-32302-0</identifier>
    <identifier type="isbn">978-1-003-32302-0</identifier>
    <identifier type="doi">10.1201/9781003323020-146</identifier>
    <identifier type="urn">urn:nbn:de:kobv:b43-582175</identifier>
    <enrichment key="eventName">The Eighth International Symposium on Life-Cycle Civil Engineering (IALCCE 2023)</enrichment>
    <enrichment key="eventPlace">Milano, Italien</enrichment>
    <enrichment key="eventStart">02.07.2023</enrichment>
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    <licence>Creative Commons - CC BY - Namensnennung 4.0 International</licence>
    <author>Annika Robens-Radermacher</author>
    <author>Jörg F. Unger</author>
    <author>Alexander Mezhov</author>
    <author>Wolfram Schmidt</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>3D concrete printing</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Material characterization</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Structural build-up</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Thixotropy</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Model calibration</value>
    </subject>
    <collection role="ddc" number="620">Ingenieurwissenschaften und zugeordnete Tätigkeiten</collection>
    <collection role="ddc" number="624">Ingenieurbau</collection>
    <collection role="institutes" number="">7 Bauwerkssicherheit</collection>
    <collection role="institutes" number="">7.4 Baustofftechnologie</collection>
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    <collection role="themenfelder" number="">Material</collection>
    <collection role="literaturgattung" number="">Verlagsliteratur</collection>
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    <collection role="unnumberedseries" number="">Wissenschaftliche Artikel der BAM</collection>
    <collection role="institutes" number="">7.7 Modellierung und Simulation</collection>
    <thesisPublisher>Bundesanstalt für Materialforschung und -prüfung (BAM)</thesisPublisher>
    <file>https://opus4.kobv.de/opus4-bam/files/58217/2023_Robens_Radermacher_IAl2023.pdf</file>
  </doc>
  <doc>
    <id>50604</id>
    <completedYear/>
    <publishedYear>2019</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>1248</pageFirst>
    <pageLast>1267</pageLast>
    <pageNumber/>
    <edition/>
    <issue>6</issue>
    <volume>121</volume>
    <type>article</type>
    <publisherName>Wiley Online Libary</publisherName>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>1</belongsToBibliography>
    <completedDate>--</completedDate>
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    <title language="eng">Explicit dynamics in impact simulation using a NURBS contact interface</title>
    <abstract language="eng">In this paper, the impact problem and the subsequent wave Propagation are considered. For the contact discretization an intermediate non-uniform rational B-spline (NURBS) layer is added between the contacting finite element bodies, which allows a smooth contact formulation and efficient element-based integration.&#13;
The impact event is ill-posed and requires a regularization to avoid propagating stress oscillations. A nonlinear mesh-dependent penalty regularization is used, where the stiffness of the penalty regularization increases upon mesh refinement. Explicit time integration methods are well suited for wave propagation problems, but are efficient only for diagonal mass matrices. Using a spectral element discretization in combination with a NURBS contact layer the bulk part of the mass matrix is diagonal.</abstract>
    <parentTitle language="eng">International Journal for Numerical Methods in Engineering</parentTitle>
    <identifier type="doi">10.1002/nme.6264</identifier>
    <identifier type="urn">urn:nbn:de:kobv:b43-506041</identifier>
    <enrichment key="date_peer_review">01.04.2020</enrichment>
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    <licence>Creative Commons - CC BY - Namensnennung 4.0 International</licence>
    <author>Peter Otto</author>
    <author>L. de Lorenzis</author>
    <author>Jörg F. Unger</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Explicit dynamics</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Impact simulation</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Isogeometric analysis</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>mortar method</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>spectral elements</value>
    </subject>
    <collection role="ddc" number="624">Ingenieurbau</collection>
    <collection role="literaturgattung" number="">Verlagsliteratur</collection>
    <collection role="fulltextaccess" number="">Datei für die Öffentlichkeit verfügbar ("Open Access")</collection>
    <collection role="unnumberedseries" number="">Wissenschaftliche Artikel der BAM</collection>
    <thesisPublisher>Bundesanstalt für Materialforschung und -prüfung (BAM)</thesisPublisher>
    <file>https://opus4.kobv.de/opus4-bam/files/50604/2019_Otto_Explicit dynamics in impact simulation using a NURBS contact interface_.pdf</file>
  </doc>
  <doc>
    <id>47787</id>
    <completedYear/>
    <publishedYear>2019</publishedYear>
    <thesisYearAccepted/>
    <language>deu</language>
    <pageFirst>1</pageFirst>
    <pageLast>5</pageLast>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume>169</volume>
    <type>conferenceobject</type>
    <publisherName>Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP)</publisherName>
    <publisherPlace>Berlin</publisherPlace>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>--</completedDate>
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    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="deu">Überwachung von Stahlbetonbrücken - Ein Modellprojekt</title>
    <abstract language="deu">Die Brücken im Netz der Bundesverkehrswege sind überwiegend in einem ausreichenden bis guten Zustand. Allerdings steigt der Unterhalts- und Sanierungsaufwand aufgrund des inzwischen hohen Alters vieler Brücken sowie des ständig wachsenden Schwerlastverkehrs. Techniken zur Einschätzung der verbleibenden Lebensdauer von Brücken sowie zur dauerhaften Beobachtung des Tragverhaltens bzw. des Erfolges von Sanierungsmaßnahmen werden daher für den sicheren und wirtschaftlichen Betrieb dringend benötigt. Zur Evaluierung dafür geeigneter holistischer Ansätze wurde in der BAM das Projekt BLEIB - Bewertung, Lebensdauerprognose und Instandsetzung von Brückenbauwerken - ins Leben gerufen.&#13;
Ein zentrales Ergebnis des Projektes ist eine extern vorgespannte Stahlbetonbrücke als Zweifeldträger mit einer Gesamtlänge von 24 m, die für den Test verschiedenster Sensorsysteme, zur Validierung numerischer Modelle und zur Erprobung von Sanierungs- und Verstärkungsmaßnahmen entwickelt wurde. Für die Simulation unterschiedlicher Schädigungsgrade kann die Vorspannung der Brücke variiert werden. Die Brücke wird mit beweglichen Gewichten belastet und über einen Shaker zum Schwingen angeregt.&#13;
Das Brückenmodell wurde bewusst geschädigt, indem die Vorspannung der Struktur erstmalig schrittweise bis auf null reduziert wurde. Unter der Eigenlast verformte sich die Brücke, wodurch eine Rissbildung im Beton einsetzte. Die Zugspannung, die zuvor durch die Vorspannung aufgenommen wurde, übernahm Schritt für Schritt der Beton. Als die Zugspannungen die relativ geringe Zugfestigkeit des Betons überstiegen, begann dieser zu reißen und die schlaffe Bewehrung der Struktur nahm die Spannungen auf. Dieser Versuch wurde unter anderem von Schallemissionsmessungen begleitet. Der Rissbildungsprozess konnte damit, bei gleichzeitiger Aufzeichnung der Vorspannung, früh detektiert und die Risse geortet werden. Die Ergebnisse korrelieren gut mit den Ergebnissen der stereophotogrammetrischen Verformungsmessungen der Struktur.</abstract>
    <parentTitle language="deu">DGZfP-Berichtsband</parentTitle>
    <identifier type="isbn">978-3-947971-00-8</identifier>
    <identifier type="urn">urn:nbn:de:kobv:b43-477878</identifier>
    <enrichment key="eventName">22. Kolloquium Schallemission und 3. Anwenderseminar Zustandsüberwachung mit geführten Wellen</enrichment>
    <enrichment key="eventPlace">Karlsruhe, Germany</enrichment>
    <enrichment key="eventStart">27.03.2019</enrichment>
    <enrichment key="eventEnd">28.03.2019</enrichment>
    <licence>Creative Commons - Namensnennung - Keine Bearbeitung 3.0</licence>
    <author>Stephan Pirskawetz</author>
    <author>Klaus-Peter Gründer</author>
    <author>Daniel Kadoke</author>
    <author>Jörg F. Unger</author>
    <subject>
      <language>deu</language>
      <type>uncontrolled</type>
      <value>Brückenmonitoring</value>
    </subject>
    <subject>
      <language>deu</language>
      <type>uncontrolled</type>
      <value>Schallemissionsanalyse</value>
    </subject>
    <collection role="ddc" number="624">Ingenieurbau</collection>
    <collection role="fulltextaccess" number="">Datei für die Öffentlichkeit verfügbar ("Open Access")</collection>
    <collection role="literaturgattung" number="">Graue Literatur</collection>
    <collection role="unnumberedseries" number="">Wissenschaftliche Artikel der BAM</collection>
    <thesisPublisher>Bundesanstalt für Materialforschung und -prüfung (BAM)</thesisPublisher>
    <file>https://opus4.kobv.de/opus4-bam/files/47787/2019_Pirskawetz et al_DGZfP Berichtsband 169 .pdf</file>
  </doc>
  <doc>
    <id>48361</id>
    <completedYear/>
    <publishedYear>2019</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>04019040-1</pageFirst>
    <pageLast>04019040-13</pageLast>
    <pageNumber/>
    <edition/>
    <issue>7</issue>
    <volume>145</volume>
    <type>article</type>
    <publisherName>ASCE - American Society of Civil Engineers</publisherName>
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    <title language="eng">Implicit explicit integration of gradient enhanced damage models</title>
    <abstract language="eng">Quasi-brittle materials exhibit strain softening. Their modeling requires regularized constitutive formulations to avoid instabilities on the material level. A commonly used model is the implicit gradient-enhanced damage model. For complex geometries, it still Shows structural instabilities when integrated with classical backward Euler schemes. An alternative is the implicit–explicit (IMPL-EX) Integration scheme. It consists of the extrapolation of internal variables followed by an implicit calculation of the solution fields. The solution procedure for the nonlinear gradient-enhanced damage model is thus transformed into a sequence of problems that are algorithmically linear in every time step. Therefore, they require one single Newton–Raphson iteration per time step to converge. This provides both additional robustness and computational acceleration. The introduced extrapolation error is controlled by adaptive time-stepping schemes. This paper introduced and assessed two novel classes of error control schemes that provide further Performance improvements. In a three-dimensional compression test for a mesoscale model of concrete, the presented scheme was about 40 times faster than an adaptive backward Euler time integration.</abstract>
    <parentTitle language="eng">JOURNAL OF ENGINEERING MECHANICS</parentTitle>
    <identifier type="doi">10.1061/(ASCE)EM.1943-7889.0001608</identifier>
    <identifier type="issn">0733-9399</identifier>
    <identifier type="issn">1943-7889</identifier>
    <enrichment key="date_peer_review">02.07.2019</enrichment>
    <author>Thomas Titscher</author>
    <author>Jörg F. Unger</author>
    <author>J. Oliver</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Implicit explicit schemes</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Gradient-enhanced damage model</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Adaptive time stepping</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Continuum damage</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Robustness</value>
    </subject>
    <collection role="ddc" number="624">Ingenieurbau</collection>
    <collection role="literaturgattung" number="">Verlagsliteratur</collection>
    <collection role="fulltextaccess" number="">Datei im Netzwerk der BAM verfügbar ("Closed Access")</collection>
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  <doc>
    <id>48479</id>
    <completedYear/>
    <publishedYear>2019</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst/>
    <pageLast/>
    <pageNumber/>
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    <title language="eng">Combination of model reduction and adaptive subset simulation for structural reliability problems</title>
    <abstract language="eng">A safe and robust design is a key criterion when building a structure or a component. Ensuring this criterion can either be performed by fullfilling prescribed safety margins, or by using a full probabilistic approach with a computation of the failure probability. The latter approach is particularly well suited for complex Problems with an interaction of different physical penomena that can be described in a numerical model. The bottleneck in this approach is the computational effort. Sampling methods such as Markov chain Monte Carlo methods are often used to evaluate the system reliability. Due to small failure probabilities (e.g. 10^6) and complex physical models with already and extensive computational effort for a single set of parameters, these methods a prohibitively expensive. The focus of this contribution is to demonstrate the advantages of combining model reduction techniques within the concept a variance reducing adaptive sampling procedures. In the developed method, a modification of the adaptive subset simulation based on Papaioannou et al. 2015 is used and coupled with a limit state function based on Proper Generalized Decomposition (PGD) (Chinesta et al. 2011). In the subset simulation the failure probability is expressed as a product of larger conditional failure probabilities. The intermediate failure events are chosen as a decreasing sequence. Instead of solving each conditional probability with a Markov chain approach, an importance sampling approach is used. It is be shown that the accuracy of the estimation depends mainly on the number of samples in the last sub-problem. For model reduction, the PGD approach is used to solve the structural problem a priori for a given Parameter space (physical space plus all random parameters). The PGD approach results in an approximation of the problem output within a prescribed range of all input Parameters (load factor, material properties, ..). The approximation of the solution by a separated form allows an evaluation of the limit state function within the sampling algorithm with almost no cost. This coupled PGD – adaptive subset Simulation approach is used to estimate the failure probability of examples with different complexity. The convergence, the error propagation as well as the reduction in computational time is discussed.</abstract>
    <enrichment key="eventName">UNCECOMP 3rd International Conference on Uncertainty Quantification in Computational Sciences and Engineering</enrichment>
    <enrichment key="eventPlace">Crete, Greece</enrichment>
    <enrichment key="eventStart">26.06.2019</enrichment>
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    <author>Jörg F. Unger</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Model reduction</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Reliability analysis</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Simulation</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Finite Elemente Method (FEM)</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Proper Generalized Decomposition (PGD)</value>
    </subject>
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  </doc>
  <doc>
    <id>49494</id>
    <completedYear/>
    <publishedYear>2019</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>1</pageFirst>
    <pageLast>21</pageLast>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume/>
    <type>article</type>
    <publisherName>Wiley Online Libary</publisherName>
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    <belongsToBibliography>1</belongsToBibliography>
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    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Explicit dynamics in impact simulation using a NURBS contact interface</title>
    <abstract language="eng">In this paper, the impact problem and the subsequent wave propagation are considered. For the contact discretization an intermediate NURBS layer is added between the contacting finite element bodies, which allows a smooth contact formulation and efficient element‐based integration. The impact event is ill‐posed and requires a regularization to avoid propagating stress oscillations. A nonlinear mesh dependent penalty regularization is used, where the stiffness of the penalty regularization increases upon mesh refinement. Explicit time integration methods are well suited for wave propagation problems, but are efficient only for diagonal mass matrices. Using a spectral element discretization and the coupled FE‐NURBS approach the bulk part of the mass matrix is diagonal.</abstract>
    <parentTitle language="eng">International Journal for Numerical Methods in Engineering</parentTitle>
    <identifier type="doi">10.1002/nme.6264</identifier>
    <identifier type="urn">urn:nbn:de:kobv:b43-494947</identifier>
    <enrichment key="date_peer_review">18.12.2019</enrichment>
    <licence>Creative Commons - CC BY - Namensnennung 4.0 International</licence>
    <author>Peter Otto</author>
    <author>L. Lorenzis</author>
    <author>Jörg F. Unger</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Impact simulation</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Explicit dynamics</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Isogeometric analysis</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Spectral elements</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Mortar method</value>
    </subject>
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    <collection role="fulltextaccess" number="">Datei für die Öffentlichkeit verfügbar ("Open Access")</collection>
    <collection role="unnumberedseries" number="">Wissenschaftliche Artikel der BAM</collection>
    <thesisPublisher>Bundesanstalt für Materialforschung und -prüfung (BAM)</thesisPublisher>
    <file>https://opus4.kobv.de/opus4-bam/files/49494/Otto_et_al-2019-International_Journal_for_Numerical_Methods_in_Engineering.pdf</file>
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  <doc>
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    <publishedYear>2019</publishedYear>
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    <language>eng</language>
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    <pageLast>2</pageLast>
    <pageNumber/>
    <edition/>
    <issue>1</issue>
    <volume>19</volume>
    <type>article</type>
    <publisherName>Wiley- VCH Verlag GmbH</publisherName>
    <publisherPlace>Weinheim</publisherPlace>
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    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>--</completedDate>
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    <title language="eng">Efficient reliability analysis coupling importance sampling using adaptive subset simulation and PGD model reduction</title>
    <abstract language="eng">One of the most important goals in civil engineering is to guaranty the safety of constructions. National standards prescribe a required failure probability in the order of 10−6 (e.g. DIN EN 199:2010-12). The estimation of these failure probabilities is the key point of structural reliability analysis. Generally, it is not possible to compute the failure probability analytically.&#13;
Therefore, simulation-based methods as well as methods based on surrogate modeling or response surface methods have been developed. Nevertheless, these methods still require a few thousand evaluations of the structure, usually with finite element (FE) simulations, making reliability analysis computationally expensive for relevant applications.&#13;
The aim of this contribution is to increase the efficiency of structural reliability analysis by using the advantages of model reduction techniques. Model reduction is a popular concept to decrease the computational effort of complex numerical simulations while maintaining a reasonable accuracy. Coupling a reduced model with an efficient variance reducing sampling algorithm significantly reduces the computational cost of the reliability analysis without a relevant loss of accuracy.</abstract>
    <parentTitle language="eng">PAMM · Proceeeding Applied Mathmatics  Mechanics</parentTitle>
    <identifier type="doi">10.1002/pamm.201900169</identifier>
    <enrichment key="eventName">GAMM - Gesellschaft für Angewandte Mathematik und Mechanik e.V.</enrichment>
    <enrichment key="eventPlace">Wien, Austria</enrichment>
    <enrichment key="eventStart">18.02.2019</enrichment>
    <enrichment key="eventEnd">22.02.2019</enrichment>
    <enrichment key="opus.doi.autoCreate">false</enrichment>
    <enrichment key="opus.urn.autoCreate">true</enrichment>
    <author>Annika Robens-Radermacher</author>
    <author>Jörg F. Unger</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>PGD model reduction</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Numerical models</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>FE modelling</value>
    </subject>
    <collection role="ddc" number="624">Ingenieurbau</collection>
    <collection role="fulltextaccess" number="">Datei im Netzwerk der BAM verfügbar ("Closed Access")</collection>
    <collection role="literaturgattung" number="">Graue Literatur</collection>
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