@inproceedings{UngerKoenke, author = {Unger, J{\"o}rg F. and K{\"o}nke, Carsten}, title = {DISCRETE CRACK SIMULATION OF CONCRETE USING THE EXTENDED FINITE ELEMENTMETHOD}, editor = {G{\"u}rlebeck, Klaus and K{\"o}nke, Carsten}, organization = {Bauhaus-Universit{\"a}t Weimar}, doi = {10.25643/bauhaus-universitaet.3030}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170327-30303}, pages = {12}, abstract = {The extended finite element method (XFEM) offers an elegant tool to model material discontinuities and cracks within a regular mesh, so that the element edges do not necessarily coincide with the discontinuities. This allows the modeling of propagating cracks without the requirement to adapt the mesh incrementally. Using a regular mesh offers the advantage, that simple refinement strategies based on the quadtree data structure can be used to refine the mesh in regions, that require a high mesh density. An additional benefit of the XFEM is, that the transmission of cohesive forces through a crack can be modeled in a straightforward way without introducing additional interface elements. Finally different criteria for the determination of the crack propagation angle are investigated and applied to numerical tests of cracked concrete specimens, which are compared with experimental results.}, subject = {Architektur }, language = {en} } @article{UngerKoenke, author = {Unger, J{\"o}rg F. and K{\"o}nke, Carsten}, title = {Coupling of scales in a multiscale simulation using neural networks}, series = {Computers \& Structures}, journal = {Computers \& Structures}, abstract = {Coupling of scales in a multiscale simulation using neural networks}, subject = {Angewandte Mathematik}, language = {en} } @inproceedings{UngerKoenke, author = {Unger, J{\"o}rg F. and K{\"o}nke, Carsten}, title = {PARAMETER IDENTIFICATION OF MESOSCALE MODELS FROM MACROSCOPIC TESTS USING BAYESIAN NEURAL NETWORKS}, editor = {G{\"u}rlebeck, Klaus and K{\"o}nke, Carsten}, organization = {Bauhaus-Universit{\"a}t Weimar}, issn = {1611-4086}, doi = {10.25643/bauhaus-universitaet.2898}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170314-28984}, pages = {5}, abstract = {In this paper, a parameter identification procedure using Bayesian neural networks is proposed. Based on a training set of numerical simulations, where the material parameters are simulated in a predefined range using Latin Hypercube sampling, a Bayesian neural network, which has been extended to describe the noise of multiple outputs using a full covariance matrix, is trained to approximate the inverse relation from the experiment (displacements, forces etc.) to the material parameters. The method offers not only the possibility to determine the parameters itself, but also the accuracy of the estimate and the correlation between these parameters. As a result, a set of experiments can be designed to calibrate a numerical model.}, subject = {Angewandte Informatik}, language = {en} } @article{UngerEckardtKoenke, author = {Unger, J{\"o}rg F. and Eckardt, Stefan and K{\"o}nke, Carsten}, title = {Modelling of cohesive crack growth in concrete structures with the extended finite element method}, series = {Computer Methods in Applied Mechanics and Engineering}, journal = {Computer Methods in Applied Mechanics and Engineering}, pages = {4087 -- 4100}, abstract = {Modelling of cohesive crack growth in concrete structures with the extended finite element method}, subject = {Angewandte Mathematik}, language = {en} } @inproceedings{TheilerKoenke, author = {Theiler, Michael and K{\"o}nke, Carsten}, title = {Damping in Bolted Joints}, series = {Proceedings of International Conference on Structural Engineering Dynamics (ICEDyn) 2013}, booktitle = {Proceedings of International Conference on Structural Engineering Dynamics (ICEDyn) 2013}, editor = {Maia, Nuno}, isbn = {978-989-96276-4-2}, doi = {10.25643/bauhaus-universitaet.1970}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20130701-19709}, pages = {8}, abstract = {With the help of modern CAE-based simulation processes, it is possible to predict the dynamic behavior of fatigue strength problems in order to improve products of many industries, e.g. the building, the machine construction or the automotive industry. Amongst others, it can be used to improve the acoustic design of automobiles in an early development stage. Nowadays, the acoustics of automobiles plays a crucial role in the process of vehicle development. Because of the advanced demand of comfort and due to statutory rules the manufacturers are faced with the challenge of optimizing their car's sound emissions. The optimization includes not only the reduction of noises. Lately with the trend to hybrid and electric cars, it has been shown that vehicles can become too quiet. Thus, the prediction of structural and acoustic properties based on FE-simulations is becoming increasingly important before any experimental prototype is examined. With the state of the art, qualitative comparisons between different implementations are possible. However, an accurate and reliable quantitative prediction is still a challenge. One aspect in the context of increasing the prediction quality of acoustic (or general oscillating) problems - especially in power-trains of automobiles - is the more accurate implementation of damping in joint structures. While material damping occurs globally and homogenous in a structural system, the damping due to joints is a very local problem, since energy is especially dissipated in the vicinity of joints. This paper focusses on experimental and numerical studies performed on a single (extracted) screw connection. Starting with experimental studies that are used to identify the underlying physical model of the energy loss, the locally influencing parameters (e.g. the damping factor) should be identified. In contrast to similar research projects, the approach tends to a more local consideration within the joint interface. Tangential stiffness and energy loss within the interface are spatially distributed and interactions between the influencing parameters are regarded. As a result, the damping matrix is no longer proportional to mass or stiffness matrix, since it is composed of the global material damping and the local joint damping. With this new approach, the prediction quality can be increased, since the local distribution of the physical parameters within the joint interface corresponds much closer to the reality.}, subject = {Damping}, language = {en} } @article{SchraderKoenke, author = {Schrader, Kai and K{\"o}nke, Carsten}, title = {Distributed computing for the nonlinear analysis of multiphase composites}, series = {Advances in Engineering Software}, journal = {Advances in Engineering Software}, pages = {20 -- 32}, abstract = {Distributed computing for the nonlinear analysis of multiphase composites}, subject = {Angewandte Mathematik}, language = {en} } @article{SchraderKoenke, author = {Schrader, Kai and K{\"o}nke, Carsten}, title = {Hybrid computing models for large-scale heterogeneous 3d microstructures}, series = {International Journal for Multiscale Computational Engineering}, journal = {International Journal for Multiscale Computational Engineering}, pages = {365 -- 377}, abstract = {Hybrid computing models for large-scale heterogeneous 3d microstructures}, subject = {Angewandte Mathematik}, language = {en} } @inproceedings{SchraderKoenke, author = {Schrader, Kai and K{\"o}nke, Carsten}, title = {SPARSE APPROXIMATE COMPUTATION OF SADDLE POINT PROBLEMS ARISING FROM FETI-DP DISCRETIZATION}, editor = {G{\"u}rlebeck, Klaus and K{\"o}nke, Carsten}, organization = {Bauhaus-Universit{\"a}t Weimar}, issn = {1611-4086}, doi = {10.25643/bauhaus-universitaet.2887}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170314-28874}, pages = {12}, abstract = {The numerical simulation of microstructure models in 3D requires, due to enormous d.o.f., significant resources of memory as well as parallel computational power. Compared to homogeneous materials, the material hetrogeneity on microscale induced by different material phases demand for adequate computational methods for discretization and solution process of the resulting highly nonlinear problem. To enable an efficient/scalable solution process of the linearized equation systems the heterogeneous FE problem will be described by a FETI-DP (Finite Element Tearing and Interconnecting - Dual Primal) discretization. The fundamental FETI-DP equation can be solved by a number of different approaches. In our approach the FETI-DP problem will be reformulated as Saddle Point system, by eliminating the primal and Lagrangian variables. For the reduced Saddle Point system, only defined by interior and dual variables, special Uzawa algorithms can be adapted for iteratively solving the FETI-DP saddle-point equation system (FETI-DP SPE). A conjugate gradient version of the Uzawa algorithm will be shown as well as some numerical tests regarding to FETI-DP discretization of small examples using the presented solution technique. Furthermore the inversion of the interior-dual Schur complement operator can be approximated using different techniques building an adequate preconditioning matrix and therewith leading to substantial gains in computing time efficiency.}, subject = {Angewandte Informatik}, language = {en} } @unpublished{RadmardRahmaniKoenke, author = {Radmard Rahmani, Hamid and K{\"o}nke, Carsten}, title = {Passive Control of Tall Buildings Using Distributed Multiple Tuned Mass Dampers}, doi = {10.25643/bauhaus-universitaet.3859}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20190311-38597}, pages = {43}, abstract = {The vibration control of the tall building during earthquake excitations is a challenging task due to their complex seismic behavior. This paper investigates the optimum placement and properties of the Tuned Mass Dampers (TMDs) in tall buildings, which are employed to control the vibrations during earthquakes. An algorithm was developed to spend a limited mass either in a single TMD or in multiple TMDs and distribute them optimally over the height of the building. The Non-dominated Sorting Genetic Algorithm (NSGA - II) method was improved by adding multi-variant genetic operators and utilized to simultaneously study the optimum design parameters of the TMDs and the optimum placement. The results showed that under earthquake excitations with noticeable amplitude in higher modes, distributing TMDs over the height of the building is more effective in mitigating the vibrations compared to the use of a single TMD system. From the optimization, it was observed that the locations of the TMDs were related to the stories corresponding to the maximum modal displacements in the lower modes and the stories corresponding to the maximum modal displacements in the modes which were highly activated by the earthquake excitations. It was also noted that the frequency content of the earthquake has significant influence on the optimum location of the TMDs.}, subject = {Schwingungsd{\"a}mpfer}, language = {en} } @article{NguyenTuanKoenkeBettziecheetal., author = {Nguyen-Tuan, Long and K{\"o}nke, Carsten and Bettzieche, Volker and Lahmer, Tom}, title = {Numerical modeling and validation for 3D coupled-nonlinear thermo-hydro-mechanical problems in masonry dams}, series = {Computers \& Structures}, journal = {Computers \& Structures}, pages = {143 -- 154}, abstract = {Numerical modeling and validation for 3D coupled-nonlinear thermo-hydro-mechanical problems in masonry dams}, subject = {Angewandte Mathematik}, language = {en} } @article{NasserSchwedlerWuttkeetal., author = {Nasser, Mourad and Schwedler, Michael and Wuttke, Frank and K{\"o}nke, Carsten}, title = {Seismic analysis of structural response using simplified soil-structure interaction models}, series = {Bauingenieur, D-A-CH-Mitteilungsblatt}, journal = {Bauingenieur, D-A-CH-Mitteilungsblatt}, abstract = {Seismic analysis of structural response using simplified soil-structure interaction models}, subject = {Angewandte Mathematik}, language = {en} } @article{LuuMartinezRodrigoZabeletal., author = {Luu, M. and Martinez-Rodrigo, M.D. and Zabel, Volkmar and K{\"o}nke, Carsten}, title = {H∞ optimization of fluid viscous dampers for reducing vibrations of high-speed railway bridges}, series = {Journal of Sound and Vibration}, journal = {Journal of Sound and Vibration}, pages = {2421 -- 2442}, abstract = {H∞ optimization of fluid viscous dampers for reducing vibrations of high-speed railway bridges}, subject = {Angewandte Mathematik}, language = {en} } @article{LutherKoenke, author = {Luther, Torsten and K{\"o}nke, Carsten}, title = {Coupled cohesive zone representations from 3D quasicontinuum simulation on aluminum grain boundaries}, series = {International Journal for Multiscale Computational Engineering}, journal = {International Journal for Multiscale Computational Engineering}, abstract = {Coupled cohesive zone representations from 3D quasicontinuum simulation on aluminum grain boundaries}, subject = {Angewandte Mathematik}, language = {en} } @inproceedings{LutherKoenke, author = {Luther, Torsten and K{\"o}nke, Carsten}, title = {INVESTIGATION OF CRACK GROWTH IN POLYCRYSTALLINE MESOSTRUCTURES}, editor = {G{\"u}rlebeck, Klaus and K{\"o}nke, Carsten}, organization = {Bauhaus-Universit{\"a}t Weimar}, doi = {10.25643/bauhaus-universitaet.2988}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170327-29886}, pages = {11}, abstract = {The design and application of high performance materials demands extensive knowledge of the materials damage behavior, which significantly depends on the meso- and microstructural complexity. Numerical simulations of crack growth on multiple length scales are promising tools to understand the damage phenomena in complex materials. In polycrystalline materials it has been observed that the grain boundary decohesion is one important mechanism that leads to micro crack initiation. Following this observation the paper presents a polycrystal mesoscale model consisting of grains with orthotropic material behavior and cohesive interfaces along grain boundaries, which is able to reproduce the crack initiation and propagation along grain boundaries in polycrystalline materials. With respect to the importance of modeling the geometry of the grain structure an advanced Voronoi algorithm is proposed to generate realistic polycrystalline material structures based on measured grain size distribution. The polycrystal model is applied to investigate the crack initiation and propagation in statically loaded representative volume elements of aluminum on the mesoscale without the necessity of initial damage definition. Future research work is planned to include the mesoscale model into a multiscale model for the damage analysis in polycrystalline materials.}, subject = {Architektur }, language = {en} } @article{LutherKoenke, author = {Luther, Torsten and K{\"o}nke, Carsten}, title = {Polycrystal models for the analysis of intergranular crack growth in metallic materials}, series = {Engineering Fracture Mechanics}, journal = {Engineering Fracture Mechanics}, pages = {2332 -- 2343}, abstract = {Polycrystal models for the analysis of intergranular crack growth in metallic materials}, subject = {Angewandte Mathematik}, language = {en} } @article{LahmerNguyenTuanKoenkeetal., author = {Lahmer, Tom and Nguyen-Tuan, Long and K{\"o}nke, Carsten and Bettzieche, Volker}, title = {Thermo-hydro-mechanische 3-D-Simulation von Staumauern-Modellierung und Validierung}, series = {WASSERWIRTSCHAFT}, journal = {WASSERWIRTSCHAFT}, pages = {27 -- 30}, abstract = {Thermo-hydro-mechanische 3-D-Simulation von Staumauern-Modellierung und Validierung}, subject = {Angewandte Mathematik}, language = {de} } @article{LahmerKoenkeBettzieche, author = {Lahmer, Tom and K{\"o}nke, Carsten and Bettzieche, Volker}, title = {Optimale Positionierung von Messeinrichtungen an Staumauern zur Bauwerks{\"u}berwachung}, series = {WASSERWIRTSCHAFT}, journal = {WASSERWIRTSCHAFT}, pages = {16 -- 16}, abstract = {Optimale Positionierung von Messeinrichtungen an Staumauern zur Bauwerks{\"u}berwachung}, subject = {Angewandte Mathematik}, language = {de} } @article{LahmerKoenkeBettzieche, author = {Lahmer, Tom and K{\"o}nke, Carsten and Bettzieche, Volker}, title = {Optimal positioning of sensors for the monitoring of water dams}, series = {WASSERWIRTSCHAFT}, journal = {WASSERWIRTSCHAFT}, pages = {16 -- 19}, abstract = {Optimal positioning of sensors for the monitoring of water dams}, subject = {Angewandte Mathematik}, language = {de} } @article{KoenkeEckardtHaefneretal., author = {K{\"o}nke, Carsten and Eckardt, Stefan and H{\"a}fner, Stefan and Luther, Torsten and Unger, J{\"o}rg F.}, title = {Multiscale simulation methods in damage prediction of brittle and ductile materials}, series = {International Journal for Multiscale Computational Engineering}, journal = {International Journal for Multiscale Computational Engineering}, pages = {17 -- 36}, abstract = {Multiscale simulation methods in damage prediction of brittle and ductile materials}, subject = {Angewandte Mathematik}, language = {en} } @inproceedings{HaefnerVogelKoenke, author = {H{\"a}fner, Stefan and Vogel, Frank and K{\"o}nke, Carsten}, title = {FINITE ELEMENT ANALYSIS OF TORSION FOR ARBITRARY CROSS-SECTIONS}, editor = {G{\"u}rlebeck, Klaus and K{\"o}nke, Carsten}, organization = {Bauhaus-Universit{\"a}t Weimar}, issn = {1611-4086}, doi = {10.25643/bauhaus-universitaet.2848}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170314-28483}, pages = {11}, abstract = {The present article proposes an alternative way to compute the torsional stiffness based on three-dimensional continuum mechanics instead of applying a specific theory of torsion. A thin, representative beam slice is discretized by solid finite elements. Adequate boundary conditions and coupling conditions are integrated into the numerical model to obtain a proper answer on the torsion behaviour, thus on shear center, shear stress and torsional stiffness. This finite element approach only includes general assumptions of beam torsion which are independent of cross-section geometry. These assumptions essentially are: no in-plane deformation, constant torsion and free warping. Thus it is possible to achieve numerical solutions of high accuracy for arbitrary cross-sections. Due to the direct link to three-dimensional continuum mechanics, it is possible to extend the range of torsion analysis to sections which are composed of different materials or even to heterogeneous beams on a high scale of resolution. A brief study follows to validate the implementation and results are compared to analytical solutions.}, subject = {Angewandte Informatik}, language = {en} }