Dokument-ID Dokumenttyp Verfasser/Autoren Herausgeber Haupttitel Abstract Auflage Verlagsort Verlag Erscheinungsjahr Seitenzahl Schriftenreihe Titel Schriftenreihe Bandzahl ISBN Quelle der Hochschulschrift Konferenzname Quelle:Titel Quelle:Jahrgang Quelle:Heftnummer Quelle:Erste Seite Quelle:Letzte Seite URN DOI Abteilungen OPUS4-4593 Wissenschaftlicher Artikel Zhang, Yongzheng; Ren, Huilong Implicit implementation of the nonlocal operator method: an open source code In this paper, we present an open-source code for the first-order and higher-order nonlocal operator method (NOM) including a detailed description of the implementation. The NOM is based on so-called support, dual-support, nonlocal operators, and an operate energy functional ensuring stability. The nonlocal operator is a generalization of the conventional differential operators. Combined with the method of weighed residuals and variational principles, NOM establishes the residual and tangent stiffness matrix of operate energy functional through some simple matrix without the need of shape functions as in other classical computational methods such as FEM. NOM only requires the definition of the energy drastically simplifying its implementation. The implementation in this paper is focused on linear elastic solids for sake of conciseness through the NOM can handle more complex nonlinear problems. The NOM can be very flexible and efficient to solve partial differential equations (PDEs), it's also quite easy for readers to use the NOM and extend it to solve other complicated physical phenomena described by one or a set of PDEs. Finally, we present some classical benchmark problems including the classical cantilever beam and plate-with-a-hole problem, and we also make an extension of this method to solve complicated problems including phase-field fracture modeling and gradient elasticity material. London Springer 35 Engineering with computers 2022 1 35 urn:nbn:de:gbv:wim2-20220216-45930 10.1007/s00366-021-01537-x Institut für Strukturmechanik (ISM) OPUS4-4470 Wissenschaftlicher Artikel Reichert, Ina; Olney, Peter; Lahmer, Tom Combined approach for optimal sensor placement and experimental verification in the context of tower-like structures When it comes to monitoring of huge structures, main issues are limited time, high costs and how to deal with the big amount of data. In order to reduce and manage them, respectively, methods from the field of optimal design of experiments are useful and supportive. Having optimal experimental designs at hand before conducting any measurements is leading to a highly informative measurement concept, where the sensor positions are optimized according to minimal errors in the structures' models. For the reduction of computational time a combined approach using Fisher Information Matrix and mean-squared error in a two-step procedure is proposed under the consideration of different error types. The error descriptions contain random/aleatoric and systematic/epistemic portions. Applying this combined approach on a finite element model using artificial acceleration time measurement data with artificially added errors leads to the optimized sensor positions. These findings are compared to results from laboratory experiments on the modeled structure, which is a tower-like structure represented by a hollow pipe as the cantilever beam. Conclusively, the combined approach is leading to a sound experimental design that leads to a good estimate of the structure's behavior and model parameters without the need of preliminary measurements for model updating. Springer Heidelberg 12 Journal of Civil Structural Health Monitoring 2021 volume 11 223 234 urn:nbn:de:gbv:wim2-20210804-44701 10.1007/s13349-020-00448-7 Graduiertenkolleg 1462 OPUS4-3974 Dissertation Schemmann, Christoph Optimierung von radialen Verdichterlaufrädern unter Berücksichtigung empirischer und analytischer Vorinformationen mittels eines mehrstufigen Sampling Verfahrens Turbomachinery plays an important role in many cases of energy generation or conversion. Therefore, turbomachinery is a promising approaching point for optimization in order to increase the efficiency of energy use. In recent years, the use of automated optimization strategies in combination with numerical simulation has become increasingly popular in many fields of engineering. The complex interactions between fluid and solid mechanics encountered in turbomachines on the one hand and the high computational expense needed to calculate the performance on the other hand, have, however, prevented a widespread use of these techniques in this field of engineering. The objective of this work was the development of a strategy for efficient metamodel based optimization of centrifugal compressor impellers. In this context, the main focus is the reduction of the required numerical expense. The central idea followed in this research was the incorporation of preliminary information acquired from low-fidelity computation methods and empirical correlations into the sampling process to identify promising regions of the parameter space. This information was then used to concentrate the numerically expensive high-fidelity computations of the fluid dynamic and structure mechanic performance of the impeller in these regions while still maintaining a good coverage of the whole parameter space. The development of the optimization strategy can be divided into three main tasks. Firstly, the available preliminary information had to be researched and rated. This research identified loss models based on one dimensional flow physics and empirical correlations as the best suited method to predict the aerodynamic performance. The loss models were calibrated using available performance data to obtain a high prediction quality. As no sufficiently exact models for the prediction of the mechanical loading of the impellercould be identified, a metamodel based on finite element computations was chosen for this estimation. The second task was the development of a sampling method which concentrates samples in regions of the parameter space where high quality designs are predicted by the preliminary information while maintaining a good overall coverage. As available methods like rejection sampling or Markov-chain Monte-Carlo methods did not meet the requirements in terms of sample distribution and input correlation, a new multi-fidelity sampling method called "Filtered Sampling"has been developed. The last task was the development of an automated computational workflow. This workflow encompasses geometry parametrization, geometry generation, grid generation and computation of the aerodynamic performance and the structure mechanic loading. Special emphasis was put into the development of a geometry parametrization strategy based on fluid mechanic considerations to prevent the generation of physically inexpedient designs. Finally, the optimization strategy, which utilizes the previously developed tools, was successfully employed to carry out three optimization tasks. The efficiency of the method was proven by the first and second testcase where an existing compressor design was optimized by the presented method. The results were comparable to optimizations which did not take preliminary information into account, while the required computational expense cloud be halved. In the third testcase, the method was applied to generate a new impeller design. In contrast to the previous examples, this optimization featuredlargervariationsoftheimpellerdesigns. Therefore, theapplicability of the method to parameter spaces with significantly varying designs could be proven, too. 233 urn:nbn:de:gbv:wim2-20190910-39748 10.25643/bauhaus-universitaet.3974 Institut für Strukturmechanik (ISM) OPUS4-3772 Dissertation Vollmering, Max Damage Localization of Mechanical Structures by Subspace Identification and Krein Space Based H-infinity Estimation This dissertation is devoted to the theoretical development and experimental laboratory verification of a new damage localization method: The state projection estimation error (SP2E). This method is based on the subspace identification of mechanical structures, Krein space based H-infinity estimation and oblique projections. To explain method SP2E, several theories are discussed and laboratory experiments have been conducted and analysed. A fundamental approach of structural dynamics is outlined first by explaining mechanical systems based on first principles. Following that, a fundamentally different approach, subspace identification, is comprehensively explained. While both theories, first principle and subspace identification based mechanical systems, may be seen as widespread methods, barely known and new techniques follow up. Therefore, the indefinite quadratic estimation theory is explained. Based on a Popov function approach, this leads to the Krein space based H-infinity theory. Subsequently, a new method for damage identification, namely SP2E, is proposed. Here, the introduction of a difference process, the analysis by its average process power and the application of oblique projections is discussed in depth. Finally, the new method is verified in laboratory experiments. Therefore, the identification of a laboratory structure at Leipzig University of Applied Sciences is elaborated. Then structural alterations are experimentally applied, which were localized by SP2E afterwards. In the end four experimental sensitivity studies are shown and discussed. For each measurement series the structural alteration was increased, which was successfully tracked by SP2E. The experimental results are plausible and in accordance with the developed theories. By repeating these experiments, the applicability of SP2E for damage localization is experimentally proven. 205 urn:nbn:de:gbv:wim2-20180730-37728 10.25643/bauhaus-universitaet.3772 Institut für Strukturmechanik (ISM) OPUS4-3596 Wissenschaftlicher Artikel Alalade, Muyiwa; Nguyen-Tuan, Long; Wuttke, Frank; Lahmer, Tom Damage identification in gravity dams using dynamic coupled hydro-mechanical XFEM Damage identification in gravity dams using dynamic coupled hydro-mechanical XFEM. 18 International Journal of Mechanics and Materials in Design 1 19 10.25643/bauhaus-universitaet.3596 Professur Stochastik und Optimierung OPUS4-3595 Wissenschaftlicher Artikel Kaltenbacher, Barbara; Lahmer, Tom; Mohr, Marcus; Kaltenbacher, Manfred PDE based determination of piezoelectric material tensors PDE based determination of piezoelectric material tensors. 33 European Journal of Applied Mathematics 383 416 10.25643/bauhaus-universitaet.3595 Institut für Strukturmechanik (ISM) OPUS4-3594 Wissenschaftlicher Artikel Lahmer, Tom; Kaltenbacher, Manfred; Kaltenbacher, Barbara; Lerch, Reinhard; Leder, Erich Fem-based determination of real and complex elastic, dielectric, and piezoelectric moduli in piezoceramic materials Fem-based determination of real and complex elastic, dielectric, and piezoelectric moduli in piezoceramic materials. IEEE transactions on ultrasonics, ferroelectrics, and frequency control 10.25643/bauhaus-universitaet.3594 Institut für Strukturmechanik (ISM) OPUS4-3593 Wissenschaftlicher Artikel Lahmer, Tom; Kaltenbacher, Barbara; Schulz, V. Optimal measurement selection for piezoelectric material tensor identification Optimal measurement selection for piezoelectric material tensor identification. 18 Inverse Problems in Science and Engineering 369 387 10.25643/bauhaus-universitaet.3593 Institut für Strukturmechanik (ISM) OPUS4-3592 Wissenschaftlicher Artikel Lahmer, Tom Modified Landweber iterations in a multilevel algorithm applied to inverse problems in piezoelectricity Modified Landweber iterations in a multilevel algorithm applied to inverse problems in piezoelectricity 8 Journal of Inverse and Ill-posed Problems 585 593 Institut für Strukturmechanik (ISM) OPUS4-3591 Wissenschaftlicher Artikel Hauck, A.; Lahmer, Tom; Kaltenbacher, Manfred Enhanced homogenization technique for magnetomechanical systems using the generalized finite element method Enhanced homogenization technique for magnetomechanical systems using the generalized finite element method 12 COMPEL: The international journal for computation and mathematics in electrical and electronic engineering 935 947 Institut für Strukturmechanik (ISM) OPUS4-3590 Wissenschaftlicher Artikel Lahmer, Tom; Könke, Carsten; Bettzieche, Volker Optimal positioning of sensors for the monitoring of water dams Optimal positioning of sensors for the monitoring of water dams 3 WASSERWIRTSCHAFT 16 19 Institut für Strukturmechanik (ISM) OPUS4-3589 Wissenschaftlicher Artikel Lahmer, Tom; Könke, Carsten; Bettzieche, Volker Optimale Positionierung von Messeinrichtungen an Staumauern zur Bauwerksüberwachung Optimale Positionierung von Messeinrichtungen an Staumauern zur Bauwerksüberwachung 0 WASSERWIRTSCHAFT 16 16 Institut für Strukturmechanik (ISM) OPUS4-3588 Wissenschaftlicher Artikel Lahmer, Tom Crack identification in hydro-mechanical systems with applications to gravity water dams Crack identification in hydro-mechanical systems with applications to gravity water dams 18 Inverse Problems in Science and Engineering 1083 1101 Institut für Strukturmechanik (ISM) OPUS4-3587 Wissenschaftlicher Artikel Stein, Peter; Lahmer, Tom; Bock, Sebastian Synthese und Analyse von gekoppelten Modellen im konstruktiven Ingenieurbau Synthese und Analyse von gekoppelten Modellen im konstruktiven Ingenieurbau 3 Bautechnik 8 11 Institut für Strukturmechanik (ISM) OPUS4-3586 Wissenschaftlicher Artikel Lahmer, Tom; Knabe, Tina; Nikulla, Susanne; Reuter, Markus Bewertungsmethoden für Modelle des konstruktiven Ingenieurbaus Bewertungsmethoden für Modelle des konstruktiven Ingenieurbaus 4 Bautechnik 60 64 Institut für Strukturmechanik (ISM) OPUS4-3585 Wissenschaftlicher Artikel Lahmer, Tom Optimal experimental design for nonlinear ill-posed problems applied to gravity dams Optimal experimental design for nonlinear ill-posed problems applied to gravity dams Inverse Problems Institut für Strukturmechanik (ISM) OPUS4-3584 Wissenschaftlicher Artikel Keitel, Holger; Karaki, Ghada; Lahmer, Tom; Nikulla, Susanne; Zabel, Volkmar Evaluation of coupled partial models in structural engineering using graph theory and sensitivity analysis Evaluation of coupled partial models in structural engineering using graph theory and sensitivity analysis 10 Engineering structures 3726 3736 Institut für Strukturmechanik (ISM) OPUS4-3583 Wissenschaftlicher Artikel Nanthakumar, S.S.; Lahmer, Tom; Rabczuk, Timon Detection of flaws in piezoelectric structures using extended FEM Detection of flaws in piezoelectric structures using extended FEM 16 International Journal for Numerical Methods in Engineering 373 389 Institut für Strukturmechanik (ISM) OPUS4-3582 Wissenschaftlicher Artikel Knabe, Tina; Datcheva, Maria; Lahmer, Tom; Cotecchia, F.; Schanz, Tom Identification of constitutive parameters of soil using an optimization strategy and statistical analysis Identification of constitutive parameters of soil using an optimization strategy and statistical analysis 14 Computers and Geotechnics 143 157 Institut für Strukturmechanik (ISM) OPUS4-3581 Wissenschaftlicher Artikel Vu-Bac, N.; Rafiee, Roham; Zhuang, Xiaoying; Lahmer, Tom; Rabczuk, Timon Uncertainty quantification for multiscale modeling of polymer nanocomposites with correlated parameters Uncertainty quantification for multiscale modeling of polymer nanocomposites with correlated parameters 18 Composites Part B: Engineering 446 464 Institut für Strukturmechanik (ISM) OPUS4-3580 Wissenschaftlicher Artikel Lahmer, Tom; Ilg, J.; Lerch, Reinhard Variance-based sensitivity analyses of piezoelectric models Variance-based sensitivity analyses of piezoelectric models 21 Computer Modeling in Engineering & Sciences 105 126 Institut für Strukturmechanik (ISM) OPUS4-3579 Wissenschaftlicher Artikel Zhang, Chao; Wang, Cuixia; Lahmer, Tom; He, Pengfei; Rabczuk, Timon A dynamic XFEM formulation for crack identification A dynamic XFEM formulation for crack identification 21 International Journal of Mechanics and Materials in Design 427 448 Institut für Strukturmechanik (ISM) OPUS4-3578 Wissenschaftlicher Artikel Vu-Bac, N.; Lahmer, Tom; Zhuang, Xiaoying; Nguyen-Thoi, T.; Rabczuk, Timon A software framework for probabilistic sensitivity analysis for computationally expensive models A software framework for probabilistic sensitivity analysis for computationally expensive models 12 Advances in Engineering Software 19 31 Institut für Strukturmechanik (ISM) OPUS4-3577 Wissenschaftlicher Artikel Nguyen-Tuan, Long; Lahmer, Tom; Datcheva, Maria; Stoimenova, Eugenia; Schanz, Tom A novel parameter identification approach for buffer elements involving complex coupled thermo-hydro-mechanical analyses A novel parameter identification approach for buffer elements involving complex coupled thermo-hydro-mechanical analyses 9 Computers and Geotechnics 23 32 Institut für Strukturmechanik (ISM) OPUS4-3576 Wissenschaftlicher Artikel Nguyen-Tuan, Long; Lahmer, Tom; Datcheva, Maria; Schanz, Tom Global and local sensitivity analyses for coupled thermo-hydro-mechanical problems Global and local sensitivity analyses for coupled thermo-hydro-mechanical problems International Journal for Numerical and Analytical Methods in Geomechanics Institut für Strukturmechanik (ISM) OPUS4-3575 Wissenschaftlicher Artikel Nanthakumar, S.S.; Lahmer, Tom; Zhuang, Xiaoying; Park, Harold S.; Rabczuk, Timon Topology optimization of piezoelectric nanostructures Topology optimization of piezoelectric nanostructures 19 Journal of the Mechanics and Physics of Solids 316 335 Institut für Strukturmechanik (ISM) OPUS4-3574 Wissenschaftlicher Artikel Nanthakumar, S.S.; Lahmer, Tom; Zhuang, Xiaoying; Zi, Goangseup; Rabczuk, Timon Detection of material interfaces using a regularized level set method in piezoelectric structures Detection of material interfaces using a regularized level set method in piezoelectric structures 23 Inverse Problems in Science and Engineering 153 176 Institut für Strukturmechanik (ISM) OPUS4-3573 Wissenschaftlicher Artikel Nanthakumar, S.S.; Lahmer, Tom; Rabczuk, Timon Detection of multiple flaws in piezoelectric structures using XFEM and level sets Detection of multiple flaws in piezoelectric structures using XFEM and level sets International Journal for Numerical Methods in Engineering 960 Institut für Strukturmechanik (ISM) OPUS4-3572 Wissenschaftlicher Artikel Marzban, Samira; Lahmer, Tom Conceptual implementation of the variance-based sensitivity analysis for the calculation of the first-order effects Conceptual implementation of the variance-based sensitivity analysis for the calculation of the first-order effects 22 Journal of Statistical Theory and Practice 589 611 Institut für Strukturmechanik (ISM) OPUS4-3570 Wissenschaftlicher Artikel Lahmer, Tom; Nguyen-Tuan, Long; Könke, Carsten; Bettzieche, Volker Thermo-hydro-mechanische 3-D-Simulation von Staumauern-Modellierung und Validierung Thermo-hydro-mechanische 3-D-Simulation von Staumauern-Modellierung und Validierung 3 WASSERWIRTSCHAFT 27 30 Institut für Strukturmechanik (ISM) OPUS4-3569 Wissenschaftlicher Artikel Lahmer, Tom; Bock, Sebastian; Hildebrand, Jörg; Gürlebeck, Klaus Non-destructive identification of residual stresses in steel under thermal loadings Non-destructive identification of residual stresses in steel under thermal loadings 16 Inverse Problems in Science and Engineering 1 17 Institut für Strukturmechanik (ISM) OPUS4-3568 Wissenschaftlicher Artikel Ghorashi, Seyed Shahram; Lahmer, Tom; Bagherzadeh, Amir Saboor; Zi, Goangseup; Rabczuk, Timon A stochastic computational method based on goal-oriented error estimation for heterogeneous geological materials A stochastic computational method based on goal-oriented error estimation for heterogeneous geological materials Engineering Geology Institut für Strukturmechanik (ISM) OPUS4-3566 Wissenschaftlicher Artikel Zhang, Chao; Nanthakumar, S.S.; Lahmer, Tom; Rabczuk, Timon Multiple cracks identification for piezoelectric structures Multiple cracks identification for piezoelectric structures 18 International Journal of Fracture 1 19 Institut für Strukturmechanik (ISM) OPUS4-3565 Wissenschaftlicher Artikel Nguyen-Tuan, Long; Könke, Carsten; Bettzieche, Volker; Lahmer, Tom Numerical modeling and validation for 3D coupled-nonlinear thermo-hydro-mechanical problems in masonry dams Numerical modeling and validation for 3D coupled-nonlinear thermo-hydro-mechanical problems in masonry dams 11 Computers & Structures 143 154 Institut für Strukturmechanik (ISM) OPUS4-3564 Wissenschaftlicher Artikel Göbel, Luise; Lahmer, Tom; Osburg, Andrea Uncertainty analysis in multiscale modeling of concrete based on continuum micromechanics Uncertainty analysis in multiscale modeling of concrete based on continuum micromechanics European Journal of Mechanics-A/Solids Institut für Strukturmechanik (ISM) OPUS4-3562 Wissenschaftlicher Artikel Achenbach, Marcus; Lahmer, Tom; Morgenthal, Guido Global Sensitivity Analysis of Reinforced Concrete Walls Subjected to Standard Fire - A Comparison of Methods Global Sensitivity Analysis of Reinforced Concrete Walls Subjected to Standard Fire—A Comparison of Methods 9 14th International Probabilistic Workshop 97 106 Institut für Strukturmechanik (ISM) OPUS4-3552 Wissenschaftlicher Artikel Savaidis, G.; Vormwald, Michael Hot-spot stress evaluation of fatigue in welded structural connections supported by finite element analysis Hot-spot stress evaluation of fatigue in welded structural connections supported by finite element analysis 6 International Journal of Fatigue 85 91 Institut für Strukturmechanik (ISM) OPUS4-3542 Wissenschaftlicher Artikel Savaidis, G.; Schliebner, R.; Vormwald, Michael Lebensdauerermittlung von geschweißten, mehrachsig belasteten Nutzfahrzeugkomponenten - Vergleich von Schwingfestigkeiten aus Rechnung und Versuch bei nichtproportionaler Beanspruchung Lebensdauerermittlung von geschweißten, mehrachsig belasteten Nutzfahrzeugkomponenten - Vergleich von Schwingfestigkeiten aus Rechnung und Versuch bei nichtproportionaler Beanspruchung 5 Materialprüfung 381 386 Institut für Strukturmechanik (ISM) OPUS4-3541 Wissenschaftlicher Artikel Hoffmeyer, J.; Döring, R.; Vormwald, Michael Kurzrisswachstum bei mehrachsig nichtproportionaler Beanspruchung Kurzrisswachstum bei mehrachsig nichtproportionaler Beanspruchung 7 Materialwissenschaft und Werkstofftechnik 329 336 Institut für Strukturmechanik (ISM) OPUS4-3528 Wissenschaftlicher Artikel Thumser, Rayk; Bergmann, Joachim W.; Vormwald, Michael Residual stress fields and fatigue analysis of autofrettaged parts Residual stress fields and fatigue analysis of autofrettaged parts 4 International Journal of Pressure Vessels and Piping 113 117 Institut für Strukturmechanik (ISM) OPUS4-3526 Wissenschaftlicher Artikel Bucher, Christian; Ebert, Matthias Nichtlineare Berechnung von Stahlflanschverbindungen mit gemessenen Imperfektionen Nichtlineare Berechnung von Stahlflanschverbindungen mit gemessenen Imperfektionen 6 Stahlbau 516 522 Institut für Strukturmechanik (ISM) OPUS4-3527 Wissenschaftlicher Artikel Döring, R.; Hoffmeyer, J.; Seeger, T.; Vormwald, Michael Verformungsverhalten und rechnerische Abschätzung der Ermüdungslebensdauer metallischer Werkstoffe unter mehrachsig nichtproportionaler Beanspruchung Verformungsverhalten und rechnerische Abschätzung der Ermüdungslebensdauer metallischer Werkstoffe unter mehrachsig nichtproportionaler Beanspruchung 8 Materialwissenschaft und Werkstofftechnik 280 288 Institut für Strukturmechanik (ISM) OPUS4-3514 Wissenschaftlicher Artikel Kirichuk, A.; Most, Thomas; Bucher, Christian Numerical nonlinear analysis of kinematically excited shells Numerical nonlinear analysis of kinematically excited shells 13 International Journal for Computational Civil and Structural Engineering 61 74 Institut für Strukturmechanik (ISM) OPUS4-3513 Wissenschaftlicher Artikel Döring, R.; Hoffmeyer, J.; Seeger, T.; Vormwald, Michael A plasticity model for calculating stress-strain sequences under multiaxial nonproportional cyclic loading A plasticity model for calculating stress-strain sequences under multiaxial nonproportional cyclic loading 9 Computational Materials Science 587 596 Institut für Strukturmechanik (ISM) OPUS4-3515 Wissenschaftlicher Artikel Savaidis, G.; Savaidis, A.; Schliebner, R.; Vormwald, Michael Evaluation of fatigue of fillet welded joints in vehicle components under multiaxial service loads Evaluation of fatigue of fillet welded joints in vehicle components under multiaxial service loads 19 European Structural Integrity Society 23 42 Institut für Strukturmechanik (ISM) OPUS4-3502 Wissenschaftlicher Artikel Most, Thomas; Bucher, Christian; Schorling, York Dynamic stability analysis of non-linear structures with geometrical imperfections under random loading Dynamic stability analysis of non-linear structures with geometrical imperfections under random loading 19 Journal of Sound and Vibration 381 400 Institut für Strukturmechanik (ISM) OPUS4-3487 Wissenschaftlicher Artikel Zerbst, U.; Vormwald, Michael; Andersch, C.; Mädler, K.; Pfuff, M. The development of a damage tolerance concept for railway components and its demonstration for a railway axle The development of a damage tolerance concept for railway components and its demonstration for a railway axle 30 Engineering Fracture Mechanics 209 239 Institut für Strukturmechanik (ISM) OPUS4-3486 Wissenschaftlicher Artikel Zabel, Volkmar An application of discrete wavelet analysis and connection coefficients to parametric system identification An application of discrete wavelet analysis and connection coefficients to parametric system identification 13 Structural Health Monitoring 5 18 Institut für Strukturmechanik (ISM) OPUS4-3485 Wissenschaftlicher Artikel Unger, Jörg F.; Teughels, A.; De Roeck, G. Damage detection of a prestressed concrete beam using modal strains Damage detection of a prestressed concrete beam using modal strains 7 Journal of Structural Engineering 1456 1463 Institut für Strukturmechanik (ISM) OPUS4-3484 Wissenschaftlicher Artikel Most, Thomas; Bucher, Christian A moving least squares weighting function for the element-free Galerkin method which almost fulfills essential boundary conditions A moving least squares weighting function for the element-free Galerkin method which almost fulfills essential boundary conditions 17 Structural Engineering and Mechanics 315 332 Institut für Strukturmechanik (ISM) OPUS4-3483 Wissenschaftlicher Artikel Bucher, Christian; Pham, Hoang Anh On model updating of existing structures utilizing measured dynamic responses On model updating of existing structures utilizing measured dynamic responses 8 Structure and Infrastructure Engineering 135 143 Institut für Strukturmechanik (ISM) OPUS4-3482 Wissenschaftlicher Artikel Bruhin, R.; Stock, U.A.; Drücker, J.-P.; Azhari, T.; Wippermann, J.; Albes, J.M.; Hintze, D.; Eckardt, Stefan; Könke, Carsten; Wahlers, T. Numerical simulation techniques to study the structural response of the human chest following median sternotomy Numerical simulation techniques to study the structural response of the human chest following median sternotomy 7 The Annals of Thoracic Surgery 623 630 Institut für Strukturmechanik (ISM) OPUS4-3463 Wissenschaftlicher Artikel Unger, Jörg F.; Teughels, A.; De Roeck, G. System identification and damage detection of a prestressed concrete beam System identification and damage detection of a prestressed concrete beam 7 Journal of Structural Engineering 1691 1698 Institut für Strukturmechanik (ISM) OPUS4-3462 Wissenschaftlicher Artikel Most, Thomas; Bucher, Christian Stochastic simulation of cracking in concrete structures using multi-parameter random fields Stochastic simulation of cracking in concrete structures using multi-parameter random fields 19 International Journal of Reliability and Safety 168 187 Institut für Strukturmechanik (ISM) OPUS4-3460 Wissenschaftlicher Artikel Häfner, Stefan; Eckardt, Stefan; Luther, Torsten; Könke, Carsten Mesoscale modeling of concrete: Geometry and numerics Mesoscale modeling of concrete: Geometry and numerics 11 Computers and Structures 450 461 Institut für Strukturmechanik (ISM) OPUS4-3459 Wissenschaftlicher Artikel Bucher, Christian; Frangopol, D.M. Optimization of lifetime maintenance strategies for deteriorting structures considering probabilities of violating safety, condition, and cost thresholds Optimization of lifetime maintenance strategies for deteriorting structures considering probabilities of violating safety, condition, and cost thresholds 7 Probabilistic Engineering Mechanics 1 8 Institut für Strukturmechanik (ISM) OPUS4-3446 Wissenschaftlicher Artikel Unger, Jörg F.; Eckardt, Stefan; Könke, Carsten Modelling of cohesive crack growth in concrete structures with the extended finite element method Modelling of cohesive crack growth in concrete structures with the extended finite element method 13 Computer Methods in Applied Mechanics and Engineering 4087 4100 Institut für Strukturmechanik (ISM) OPUS4-3445 Wissenschaftlicher Artikel Most, Thomas; Bucher, Christian Energy-based simulation of concrete cracking using an improved mixed-mode cohesive crack model within a meshless discretization Energy-based simulation of concrete cracking using an improved mixed-mode cohesive crack model within a meshless discretization 20 International Journal for Numerical and Analytical Methods in Geomechanics 285 305 Institut für Strukturmechanik (ISM) OPUS4-3444 Wissenschaftlicher Artikel Most, Thomas; Bucher, Christian Probabilistic analysis of concrete cracking using neural networks and random fields Probabilistic analysis of concrete cracking using neural networks and random fields 10 Probabilistic Engineering Mechanics 219 229 Institut für Strukturmechanik (ISM) OPUS4-3443 Wissenschaftlicher Artikel Most, Thomas A natural neighbour-based moving least-squares approach for the element-free Galerkin method A natural neighbour-based moving least-squares approach for the element-free Galerkin method 28 International Journal for Numerical Methods in Engineering 224 252 Institut für Strukturmechanik (ISM) OPUS4-3442 Wissenschaftlicher Artikel Macke, M.; Higuchi, Shoko Optimizing maintenance interventions for deteriorating structures using cost-benefit criteria Optimizing maintenance interventions for deteriorating structures using cost-benefit criteria 9 Journal of Structural Engineering 925 934 Institut für Strukturmechanik (ISM) OPUS4-3441 Wissenschaftlicher Artikel Higuchi, Shoko; Macke, M. Cost-benefit based optimization of maintenance interventions for deteriorating structures Cost-benefit based optimization of maintenance interventions for deteriorating structures 16 Structural Engineering/Earthquake Engineering 131 147 Institut für Strukturmechanik (ISM) OPUS4-3440 Wissenschaftlicher Artikel Higuchi, Shoko; Macke, M. Cost-benefit based optimization of maintenance interventions for deteriorating structures Cost-benefit based optimization of maintenance interventions for deteriorating structures 16 Doboku Gakkai Ronbunshuu A 727 743 Institut für Strukturmechanik (ISM) OPUS4-3414 Wissenschaftlicher Artikel Zabel, Volkmar; Brehm, Maik Das dynamische Verhalten von Eisenbahnbrücken mit kurzer Spannweite - numerische und experimentelle Untersuchungen Das dynamische Verhalten von Eisenbahnbrücken mit kurzer Spannweite - numerische und experimentelle Untersuchungen Bauingenieur, D-A-CH-Mitteilungsblatt Institut für Strukturmechanik (ISM) OPUS4-3413 Wissenschaftlicher Artikel Unger, Jörg F.; Könke, Carsten Coupling of scales in a multiscale simulation using neural networks Coupling of scales in a multiscale simulation using neural networks Computers & Structures Institut für Strukturmechanik (ISM) OPUS4-3412 Wissenschaftlicher Artikel Most, Thomas; Ishii, H.; Geng, X.; Bolzern, P.; Colaneri, P.; De Nicolao, G. Discussion on Almost sure stability of stochastic linear systems with ergodic parameters Discussion on Almost sure stability of stochastic linear systems with ergodic parameters 6 European Journal of Control 124 130 Institut für Strukturmechanik (ISM) OPUS4-3411 Wissenschaftlicher Artikel Most, Thomas; Bucher, Christian New concepts for moving least squares: An interpolating non-singular weighting function and weighted nodal least squares New concepts for moving least squares: An interpolating non-singular weighting function and weighted nodal least squares 9 Engineering Analysis with Boundary Elements 461 470 Institut für Strukturmechanik (ISM) OPUS4-3410 Wissenschaftlicher Artikel Higuchi, Shoko; Macke, M. Cost-benefit analysis for the optimal rehabilitation of deteriorating structures Cost-benefit analysis for the optimal rehabilitation of deteriorating structures 15 Structural Safety 291 306 Institut für Strukturmechanik (ISM) OPUS4-3409 Wissenschaftlicher Artikel Eckardt, Stefan; Könke, Carsten Adaptive damage simulation of concrete using heterogeneous multiscale models Adaptive damage simulation of concrete using heterogeneous multiscale models 22 Journal of Algorithms & Computational Technology 275 297 Institut für Strukturmechanik (ISM) OPUS4-3408 Wissenschaftlicher Artikel Bucher, Christian; Most, Thomas A comparison of approximate response functions in structural reliability analysis A comparison of approximate response functions in structural reliability analysis 9 Probabilistic Engineering Mechanics 154 163 Institut für Strukturmechanik (ISM) OPUS4-3407 Wissenschaftlicher Artikel Nguyen-Thanh, Nhon; Rabczuk, Timon; Nguyen-Xuan, Hung; Bordas, Stéphane Pierre Alain An alternative alpha finite element method (A?FEM) free and forced vibration analysis of solids using triangular meshes An alternative alpha finite element method (A?FEM) free and forced vibration analysis of solids using triangular meshes 23 Journal of Computational and Applied Mathematics 2112 2135 Institut für Strukturmechanik (ISM) OPUS4-3406 Wissenschaftlicher Artikel Luther, Torsten; Könke, Carsten Polycrystal models for the analysis of intergranular crack growth in metallic materials Polycrystal models for the analysis of intergranular crack growth in metallic materials 11 Engineering Fracture Mechanics 2332 2343 Institut für Strukturmechanik (ISM) OPUS4-3405 Wissenschaftlicher Artikel Nasser, Mourad; Schwedler, Michael; Wuttke, Frank; Könke, Carsten Seismic analysis of structural response using simplified soil-structure interaction models Seismic analysis of structural response using simplified soil-structure interaction models Bauingenieur, D-A-CH-Mitteilungsblatt Institut für Strukturmechanik (ISM) OPUS4-3404 Wissenschaftlicher Artikel Könke, Carsten; Eckardt, Stefan; Häfner, Stefan; Luther, Torsten; Unger, Jörg F. Multiscale simulation methods in damage prediction of brittle and ductile materials Multiscale simulation methods in damage prediction of brittle and ductile materials 19 International Journal for Multiscale Computational Engineering 17 36 Institut für Strukturmechanik (ISM) OPUS4-3403 Wissenschaftlicher Artikel Luther, Torsten; Könke, Carsten Coupled cohesive zone representations from 3D quasicontinuum simulation on aluminum grain boundaries Coupled cohesive zone representations from 3D quasicontinuum simulation on aluminum grain boundaries International Journal for Multiscale Computational Engineering Institut für Strukturmechanik (ISM) OPUS4-3402 Wissenschaftlicher Artikel Brehm, Maik; Zabel, Volkmar; Bucher, Christian An automatic mode pairing strategy using an enhanced modal assurance citerion based on modal strain energies In the context of finite element model updating using output-only vibration test data, natural frequencies and mode shapes are used as validation criteria. Consequently, the correct pairing of experimentally obtained and numerically derived natural frequencies and mode shapes is important. In many cases, only limited spatial information is available and noise is present in the measurements. Therefore, the automatic selection of the most likely numerical mode shape corresponding to a particular experimentally identified mode shape can be a difficult task. The most common criterion for indicating corresponding mode shapes is the modal assurance criterion. Unfortunately, this criterion fails in certain cases and is not reliable for automatic approaches. In this paper, the purely mathematical modal assurance criterion will be enhanced by additional physical information from the numerical model in terms of modal strain energies. A numerical example and a benchmark study with experimental data are presented to show the advantages of the proposed energy-based criterion in comparison to the traditional modal assurance criterion. 17 Journal of Sound and Vibration 5375 5392 10.1016/j.jsv.2010.07.006 Institut für Strukturmechanik (ISM) OPUS4-3401 Wissenschaftlicher Artikel Nguyen-Xuan, Hung; Rabczuk, Timon; Nguyen-Thanh, Nhon; Nguyen-Thoi, T.; Bordas, Stéphane Pierre Alain A node-based smoothed finite element method (NS-FEM) for analysis of Reissner-Mindlin plates A node-based smoothed finite element method (NS-FEM) for analysis of Reissner-Mindlin plates 22 Computational Mechanics 679 701 Institut für Strukturmechanik (ISM) OPUS4-3400 Wissenschaftlicher Artikel Nguyen-Thanh, Nhon; Thai-Hoang, C.; Nguyen-Xuan, Hung; Rabczuk, Timon A smoothed finite element method for the static and free vibration analysis of shells A smoothed finite element method for the static and free vibration analysis of shells 12 Journal of Civil Engineering and Architecture 13 25 Institut für Strukturmechanik (ISM) OPUS4-3399 Wissenschaftlicher Artikel Schrader, Kai; Könke, Carsten Hybrid computing models for large-scale heterogeneous 3d microstructures Hybrid computing models for large-scale heterogeneous 3d microstructures 12 International Journal for Multiscale Computational Engineering 365 377 Institut für Strukturmechanik (ISM) OPUS4-3398 Wissenschaftlicher Artikel Brehm, Maik; Zabel, Volkmar; Bucher, Christian Optimal reference sensor positions for applications in model updating using output-only vibration test data based on random excitation: Part 2 - improved search strategy and experimental case study Optimal reference sensor positions for applications in model updating using output-only vibration test data based on random excitation: Part 2 - improved search strategy and experimental case study Mechanical Systems and Signal Processing Institut für Strukturmechanik (ISM) OPUS4-3396 Wissenschaftlicher Artikel Nguyen-Thanh, Nhon; Rabczuk, Timon; Nguyen-Xuan, Hung; Bordas, Stéphane Pierre Alain An alternative alpha finite element method with stabilized discrete shear gap technique for analysis of Mindlin-Reissner plates An alternative alpha finite element method with stabilized discrete shear gap technique for analysis of Mindlin-Reissner plates 16 Finite Elements in Analysis & Design 519 535 Institut für Strukturmechanik (ISM) OPUS4-3395 Wissenschaftlicher Artikel Nguyen-Thanh, Nhon; Nguyen-Xuan, Hung; Bordas, Stéphane Pierre Alain; Rabczuk, Timon Isogeometric analysis using polynomial splines over hierarchical T-meshes for two-dimensional elastic solids Isogeometric analysis using polynomial splines over hierarchical T-meshes for two-dimensional elastic solids 16 Computer Methods in Applied Mechanics and Engineering 1892 1908 Institut für Strukturmechanik (ISM) OPUS4-3394 Wissenschaftlicher Artikel Nguyen-Thanh, Nhon; Kiendl, J.; Nguyen-Xuan, Hung; Wüchner, R.; Bletzinger, Kai-Uwe; Bazilevs, Yuri; Rabczuk, Timon Rotation free isogeometric thin shell analysis using PHT-splines Rotation free isogeometric thin shell analysis using PHT-splines 14 Computer Methods in Applied Mechanics and Engineering 3410 3424 Institut für Strukturmechanik (ISM) OPUS4-3393 Wissenschaftlicher Artikel Simpson, R.; Bordas, Stéphane Pierre Alain; Trevelyan, J.; Kerfriden, Pierre; Rabczuk, Timon An Isogeometric Boundary Element Method for elastostatic analysis The concept of isogeometric analysis, where functions that are used to describe geometry in CAD software are used to approximate the unknown fields in numerical simulations, has received great attention in recent years. The method has the potential to have profound impact on engineering design, since the task of meshing, which in some cases can add significant overhead, has been circumvented. Much of the research effort has been focused on finite element implementations of the isogeometric concept, but at present, little has been seen on the application to the Boundary Element Method. The current paper proposes an Isogeometric Boundary Element Method (BEM), which we term IGABEM, applied to two-dimensional elastostatic problems using Non-Uniform Rational B-Splines (NURBS). We find it is a natural fit with the isogeometric concept since both the NURBS approximation and BEM deal with quantities entirely on the boundary. The method is verified against analytical solutions where it is seen that superior accuracies are achieved over a conventional quadratic isoparametric BEM implementation. Computer Methods in Applied Mechanics and Engineering 10.1016/j.cma.2011.08.008 Institut für Strukturmechanik (ISM) OPUS4-3392 Wissenschaftlicher Artikel Chau-Dinh, T.; Zi, Goangseup; Lee, P.S.; Song, Jeong-Hoon; Rabczuk, Timon Phantom-node method for shell models with arbitrary cracks A phantom-node method is developed for three-node shell elements to describe cracks. This method can treat arbitrary cracks independently of the mesh. The crack may cut elements completely or partially. Elements are overlapped on the position of the crack, and they are partially integrated to implement the discontinuous displacement across the crack. To consider the element containing a crack tip, a new kinematical relation between the overlapped elements is developed. There is no enrichment function for the discontinuous displacement field. Several numerical examples are presented to illustrate the proposed method. Computers & Structures 10.1016/j.compstruc.2011.10.021 Institut für Strukturmechanik (ISM) OPUS4-3391 Wissenschaftlicher Artikel Talebi, Hossein; Samaniego, C.; Samaniego, Esteban; Rabczuk, Timon On the numerical stability and mass-lumping schemes for explicit enriched meshfree methods Meshfree methods (MMs) such as the element free Galerkin (EFG)method have gained popularity because of some advantages over other numerical methods such as the finite element method (FEM). A group of problems that have attracted a great deal of attention from the EFG method community includes the treatment of large deformations and dealing with strong discontinuities such as cracks. One efficient solution to model cracks is adding special enrichment functions to the standard shape functions such as extended FEM, within the FEM context, and the cracking particles method, based on EFG method. It is well known that explicit time integration in dynamic applications is conditionally stable. Furthermore, in enriched methods, the critical time step may tend to very small values leading to computationally expensive simulations. In this work, we study the stability of enriched MMs and propose two mass-lumping strategies. Then we show that the critical time step for enriched MMs based on lumped mass matrices is of the same order as the critical time step of MMs without enrichment. Moreover, we show that, in contrast to extended FEM, even with a consistent mass matrix, the critical time step does not vanish even when the crack directly crosses a node. 18 International Journal for Numerical Methods in Engineering 1009 1027 10.1002/nme.3275 Institut für Strukturmechanik (ISM) OPUS4-3390 Wissenschaftlicher Artikel Chen, Lei; Rabczuk, Timon; Liu, G.R.; Zeng, K.Y.; Kerfriden, Pierre; Bordas, Stéphane Pierre Alain Extended finite element method with edge-based strain smoothing (ESm-XFEM) for linear elastic crack growth This paper presents a strain smoothing procedure for the extended finite element method (XFEM). The resulting "edge-based" smoothed extended finite element method (ESm-XFEM) is tailored to linear elastic fracture mechanics and, in this context, to outperform the standard XFEM. In the XFEM, the displacement-based approximation is enriched by the Heaviside and asymptotic crack tip functions using the framework of partition of unity. This eliminates the need for the mesh alignment with the crack and re-meshing, as the crack evolves. Edge-based smoothing (ES) relies on a generalized smoothing operation over smoothing domains associated with edges of simplex meshes, and produces a softening effect leading to a close-to-exact stiffness, "super-convergence" and "ultra-accurate" solutions. The present method takes advantage of both the ES-FEM and the XFEM. Thanks to the use of strain smoothing, the subdivision of elements intersected by discontinuities and of integrating the (singular) derivatives of the approximation functions is suppressed via transforming interior integration into boundary integration. Numerical examples show that the proposed method improves significantly the accuracy of stress intensity factors and achieves a near optimal convergence rate in the energy norm even without geometrical enrichment or blending correction. Computer Methods in Applied Mechanics and Engineering 10.1016/j.cma.2011.08.013 Institut für Strukturmechanik (ISM) OPUS4-3389 Wissenschaftlicher Artikel Nguyen-Xuan, Hung; Rabczuk, Timon; Nguyen-Thoi, T.; Tran, T.; Nguyen-Thanh, Nhon Computation of limit and shakedown loads using a node-based smoothed finite element method This paper presents a novel numerical procedure for computing limit and shakedown loads of structures using a node-based smoothed FEM in combination with a primal-dual algorithm. An associated primal-dual form based on the von Mises yield criterion is adopted. The primal-dual algorithm together with a Newton-like iteration are then used to solve this associated primal-dual form to determine simultaneously both approximate upper and quasi-lower bounds of the plastic collapse limit and the shakedown limit. The present formulation uses only linear approximations and its implementation into finite element programs is quite simple. Several numerical examples are given to show the reliability, accuracy, and generality of the present formulation compared with other available methods. 23 International Journal for Numerical Methods in Engineering 287 310 10.1002/nme.3317 Institut für Strukturmechanik (ISM) OPUS4-3388 Wissenschaftlicher Artikel Areias, Pedro; Rabczuk, Timon; Dias-da-Costa, D.; Piresh, E.B. Implicit solutions with consistent additive and multiplicative components This work describes an algorithm and corresponding software for incorporating general nonlinear multiple-point equality constraints in a implicit sparse direct solver. It is shown that direct addressing of sparse matrices is possible in general circumstances, circumventing the traditional linear or binary search for introducing (generalized) constituents to a sparse matrix. Nested and arbitrarily interconnected multiple-point constraints are introduced by processing of multiplicative constituents with a built-in topological ordering of the resulting directed graph. A classification of discretization methods is performed and some re-classified problems are described and solved under this proposed perspective. The dependence relations between solution methods, algorithms and constituents becomes apparent. Fracture algorithms can be naturally casted in this framework. Solutions based on control equations are also directly incorporated as equality constraints. We show that arbitrary constituents can be used as long as the resulting directed graph is acyclic. It is also shown that graph partitions and orderings should be performed in the innermost part of the algorithm, a fact with some peculiar consequences. The core of our implicit code is described, specifically new algorithms for direct access of sparse matrices (by means of the clique structure) and general constituent processing. It is demonstrated that the graph structure of the second derivatives of the equality constraints are cliques (or pseudo-elements) and are naturally included as such. A complete algorithm is presented which allows a complete automation of equality constraints, avoiding the need of pre-sorting. Verification applications in four distinct areas are shown: single and multiple rigid body dynamics, solution control and computational fracture. 16 Finite Elements in Analysis and Design 15 31 10.1016/j.finel.2012.03.007 Institut für Strukturmechanik (ISM) OPUS4-3387 Wissenschaftlicher Artikel Jiang, Jin-Wu; Zhao, Jun-Hua; Zhou, K.; Rabczuk, Timon Superior thermal conductivity and extremely high mechanical strength in polyethylene chains from ab initio calculation The upper limit of the thermal conductivity and the mechanical strength are predicted for the polyethylene chain, by performing the ab initio calculation and applying the quantum mechanical non-equilibrium Green's function approach. Specially, there are two main findings from our calculation: (1) the thermal conductivity can reach a high value of 310 Wm−1 K−1 in a 100 nm polyethylene chain at room temperature and the thermal conductivity increases with the length of the chain; (2) the Young's modulus in the polyethylene chain is as high as 374.5 GPa, and the polyethylene chain can sustain 32.85%±0.05% (ultimate) strain before undergoing structural phase transition into gaseous ethylene. Journal of Applied Physics 10.1063/1.4729489 Institut für Strukturmechanik (ISM) OPUS4-3386 Wissenschaftlicher Artikel Jiang, Jin-Wu; Wang, Bing-Shen; Rabczuk, Timon Acoustic and breathing phonon modes in bilayer graphene with Moire-acute patterns The lattice dynamics properties are investigated for twisting bilayer graphene. There are big jumps for the inter-layer potential at twisting angle θ=0° and 60°, implying the stability of Bernal-stacking and the instability of AA-stacking structures, while a long platform in [8,55]° indicates the ease of twisting bilayer graphene in this wide angle range. Significant frequency shifts are observed for the z breathing mode around θ=0° and 60°, while the frequency is a constant in a wide range [8,55]°. Using the z breathing mode, a mechanical nanoresonator is proposed to operate on a robust resonant frequency in terahertz range. Applied Physics Letters 10.1063/1.4735246 Institut für Strukturmechanik (ISM) OPUS4-3385 Wissenschaftlicher Artikel Talebi, Hossein; Zi, Goangseup; Silani, Mohammad; Samaniego, Esteban; Rabczuk, Timon A simple circular cell method for multilevel finite element analysis A simple multiscale analysis framework for heterogeneous solids based on a computational homogenization technique is presented. The macroscopic strain is linked kinematically to the boundary displacement of a circular or spherical representative volume which contains the microscopic information of the material. The macroscopic stress is obtained from the energy principle between the macroscopic scale and the microscopic scale. This new method is applied to several standard examples to show its accuracy and consistency of the method proposed. Journal of Applied Mathematics 10.1155/2012/526846 Institut für Strukturmechanik (ISM) OPUS4-3384 Wissenschaftlicher Artikel Nguyen-Vinh, H.; Bakar, I.; Msekh, Mohammed Abdulrazzak; Song, Jeong-Hoon; Muthu, Jacob; Zi, Goangseup; Le, P.; Bordas, Stéphane Pierre Alain; Simpson, R.; Natarajan, S.; Lahmer, Tom; Rabczuk, Timon Extended Finite Element Method for Dynamic Fracture of Piezo-Electric Materials We present an extended finite element formulation for dynamic fracture of piezo-electric materials. The method is developed in the context of linear elastic fracture mechanics. It is applied to mode I and mixed mode-fracture for quasi-steady cracks. An implicit time integration scheme is exploited. The results are compared to results obtained with the boundary element method and show excellent agreement. 12 Engineering Fracture Mechanics 19 31 10.1016/j.engfracmech.2012.04.025 Institut für Strukturmechanik (ISM) OPUS4-3383 Wissenschaftlicher Artikel Natarajan, S.; Chakraborty, S.; Thangavel, M.; Bordas, Stéphane Pierre Alain; Rabczuk, Timon Size dependent free flexural vibration behavior of functionally graded nanoplates Size dependent free flexural vibration behavior of functionally graded nanoplates 6 Computational Materials Science 74 80 Institut für Strukturmechanik (ISM) OPUS4-3382 Wissenschaftlicher Artikel Thai, Chien H.; Nguyen-Xuan, Hung; Nguyen-Thanh, Nhon; Le, T.H.; Nguyen-Thoi, T.; Rabczuk, Timon Static, free vibration and buckling analysis of laminated composite Reissner-Mindlin plates using NURBS-based isogeometric approach This paper presents a novel numerical procedure based on the framework of isogeometric analysis for static, free vibration, and buckling analysis of laminated composite plates using the first-order shear deformation theory. The isogeometric approach utilizes non-uniform rational B-splines to implement for the quadratic, cubic, and quartic elements. Shear locking problem still exists in the stiffness formulation, and hence, it can be significantly alleviated by a stabilization technique. Several numerical examples are presented to show the performance of the method, and the results obtained are compared with other available ones. 32 International Journal for Numerical Methods in Engineering 571 603 10.1002/nme.4282 Institut für Strukturmechanik (ISM) OPUS4-3381 Wissenschaftlicher Artikel Zhao, Jun-Hua; Guo, Wanlin; Rabczuk, Timon An analytical molecular mechanics model for the elastic properties of crystalline polyethylene We present an analytical model to relate the elastic properties of crystalline polyethylene based on a molecular mechanics approach. Along the polymer chains direction, the united-atom (UA) CH2-CH2 bond stretching, angle bending potentials are replaced with equivalent Euler-Bernoulli beams. Between any two polymer chains, the explicit formulae are derived for the van der Waals interaction represented by the linear springs of different stiffness. Then, the nine independent elastic constants are evaluated systematically using the formulae. The analytical model is finally validated by present united-atom molecular dynamics (MD) simulations and against available all-atom molecular dynamics results in the literature. The established analytical model provides an efficient route for mechanical characterization of crystalline polymers and related materials. Journal of Applied Physics 10.1063/1.4745035 Institut für Strukturmechanik (ISM) OPUS4-3379 Wissenschaftlicher Artikel Jiang, Jin-Wu; Park, Harold S.; Rabczuk, Timon Enhancing the mass sensitivity of graphene nanoresonators via nonlinear oscillations: The effective strain mechanism Enhancing the mass sensitivity of graphene nanoresonators via nonlinear oscillations: The effective strain mechanism Nanotechnology Institut für Strukturmechanik (ISM) OPUS4-3378 Wissenschaftlicher Artikel Nguyen-Xuan, Hung; Liu, G.R.; Bordas, Stéphane Pierre Alain; Natarajan, S.; Rabczuk, Timon An adaptive singular ES-FEM for mechanics problems with singular field of arbitrary order An adaptive singular ES-FEM for mechanics problems with singular field of arbitrary order 21 Computer Methods in Applied Mechanics and Engineering 252 273 Institut für Strukturmechanik (ISM) OPUS4-3377 Wissenschaftlicher Artikel Zhang, Yancheng; Zhao, Jiyun; Wei, Ning; Jiang, Jin-Wu; Rabczuk, Timon Effects of the dispersion of polymer wrapped two neighbouring single walled carbon nanotubes (SWNTs) on nanoengineering load transfer Effects of the dispersion of polymer wrapped two neighbouring single walled carbon nanotubes (SWNTs) on nanoengineering load transfer 7 Composites Part B: Engineering 1714 1721 Institut für Strukturmechanik (ISM) OPUS4-3376 Wissenschaftlicher Artikel Areias, Pedro; Rabczuk, Timon; Dias-da-Costa, D. Assumed-metric spherically-interpolated quadrilateral shell element Assumed-metric spherically-interpolated quadrilateral shell element 14 Finite Elements in Analysis and Design 53 67 Institut für Strukturmechanik (ISM)