@inproceedings{KoenigSchneiderHijazietal., author = {K{\"o}nig, Reinhard and Schneider, Sven and Hijazi, Ihab Hamzi and Li, Xin and Bielik, Martin and Schmitt, Gerhard and Donath, Dirk}, title = {Using geo statistical analysis to detect similarities in emotional responses of urban walkers to urban space}, series = {Sixth International Conference on Design Computing and Cognition (DCC14)}, booktitle = {Sixth International Conference on Design Computing and Cognition (DCC14)}, doi = {10.25643/bauhaus-universitaet.2514}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20160121-25146}, pages = {1}, abstract = {Using geo statistical analysis to detect similarities in emotional responses of urban walkers to urban space}, subject = {St{\"a}dtebau}, language = {en} } @article{IlyaniAkmarLahmerBordasetal., author = {Ilyani Akmar, A.B. and Lahmer, Tom and Bordas, St{\´e}phane Pierre Alain and Beex, L.A.A. and Rabczuk, Timon}, title = {Uncertainty quantification of dry woven fabrics: A sensitivity analysis on material properties}, series = {Composite Structures}, journal = {Composite Structures}, doi = {10.1016/j.compstruct.2014.04.014}, pages = {1 -- 17}, abstract = {Uncertainty quantification of dry woven fabrics: A sensitivity analysis on material properties}, subject = {Angewandte Mathematik}, language = {en} } @article{GhasemiRafieeZhuangetal., author = {Ghasemi, Hamid and Rafiee, Roham and Zhuang, Xiaoying and Muthu, Jacob and Rabczuk, Timon}, title = {Uncertainties propagation in metamodel-based probabilistic optimization of CNT/polymer composite structure using stochastic multi-scale modeling}, series = {Computational Materials Science}, journal = {Computational Materials Science}, pages = {295 -- 305}, abstract = {Uncertainties propagation in metamodel-based probabilistic optimization of CNT/polymer composite structure using stochastic multi-scale modeling}, subject = {Angewandte Mathematik}, language = {en} } @phdthesis{Janke, author = {Janke, Lars}, title = {Tragverhalten von Betondruckgliedern mit vorgespannter Umschn{\"u}rung aus Formged{\"a}chtnislegierungen, Stahl oder faserverst{\"a}rkten Kunststoffen}, doi = {10.25643/bauhaus-universitaet.2326}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20141023-23262}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {180}, abstract = {Druckbeanspruchte Bauteile aus Beton k{\"o}nnen mit zugfesten Umschn{\"u}rungen von außen verst{\"a}rkt werden. Mit dieser etablierten Methode konnten axiale Traglast und Duktilit{\"a}t von unzureichend bewehrten St{\"u}tzen bereits verbessert werden. Es wurde jedoch festgestellt, dass der umschn{\"u}rte Betonkern dennoch an Festigkeit verliert. Um die Wirksamkeit der Umschn{\"u}rung zu erh{\"o}hen, wird deshalb vorgeschlagen, das umschn{\"u}rende Material vorzuspannen. Dieser Vorschlag wird insbesondere von der neuen Materialgruppe der Formged{\"a}chtnislegierungen inspiriert, die thermisch vorspannbar sind. Bisher sind die Auswirkungen der Vorspannung einer Umschn{\"u}rung auf das Tragverhalten von Betondruckgliedern kaum untersucht worden. Diese L{\"u}cke wird durch systematische Versuche an Betonzylindern mit vorgespannter Umschn{\"u}rung aus Stahl und kohlenstofffaserverst{\"a}rktem Kunststoff geschlossen. Die Abbildung der Versuchsergebnisse durch geeignete Modelle erm{\"o}glicht auch Aussagen zum Verhalten von Betondruckgliedern mit Umschn{\"u}rungen aus anderen Materialien, beispielsweise Formged{\"a}chtnislegierungen. Um diese in den Berechnungen zu simulieren, wird eine f{\"u}r das Bauwesen infrage kommende eisenbasierte Legierung in separaten axialen Versuchen charakterisiert und thermisch vorgespannt. Die in der vorliegenden Arbeit entwickelten neuen Modelle orientieren sich im Wesentlichen an zwei Zielen: dem Abbilden des mehraxialen Spannungs-Dehnungs-Verhaltens des vorgespannt umschn{\"u}rten Betons und dem Berechnen der Restfestigkeit des Betons. Die durchgef{\"u}hrten Versuche und Parameterstudien auf Basis der Modelle zeigen: Die Vorspannung der Umschn{\"u}rung beeinflusst vor allem die Restfestigkeit des Betons wesentlich. Die gewonnenen Erkenntnisse und neuen Methoden k{\"o}nnen eingesetzt werden, um das Tragverhalten von Betondruckgliedern mit Umschn{\"u}rungen aus Stahl, faserverst{\"a}rktem Kunststoff oder Formged{\"a}chtnislegierungen zu bewerten.}, subject = {Beton}, language = {de} } @article{AreiasRabczukBarbosa, author = {Areias, Pedro and Rabczuk, Timon and Barbosa, J.I.}, title = {The extended unsymmetric frontal solution for multiple-point constraints}, series = {Engineering Computations}, journal = {Engineering Computations}, abstract = {The extended unsymmetric frontal solution for multiple-point constraints}, subject = {Angewandte Mathematik}, language = {en} } @article{ZhaoKouJiangetal., author = {Zhao, Jun-Hua and Kou, Liangzhi and Jiang, Jin-Wu and Rabczuk, Timon}, title = {Tension-induced phase transition of single-layer molybdenum disulphide (MoS2) at low temperatures}, series = {Nanotechnology}, journal = {Nanotechnology}, doi = {10.1088/0957-4484/25/29/295701}, abstract = {Tension-induced phase transition of single-layer molybdenum disulphide (MoS2) at low temperatures}, subject = {Angewandte Mathematik}, language = {en} } @misc{Kavrakov, type = {Master Thesis}, author = {Kavrakov, Igor}, title = {Structural Optimization of Composite Cross-Sections and Elements using Energy Methods}, doi = {10.25643/bauhaus-universitaet.3959}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20190815-39593}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {96}, abstract = {Structural optimization has gained considerable attention in the design of structural engineering structures, especially in the preliminary phase. This study introduces an unconventional approach for structural optimization by utilizing the Energy method with Integral Material Behavior (EIM), based on the Lagrange's principle of minimum potential energy. An automated two-level optimization search process is proposed, which integrates the EIM, as an alternative method for nonlinear structural analysis, and the bilevel optimization. The proposed procedure secures the equilibrium through minimizing the potential energy on one level, and on a higher level, a design objective function. For this, the most robust strategy of bilevel optimization, the nested method is used. The function of the potential energy is investigated along with its instabilities for physical nonlinear analysis through principle examples, by which the advantages and limitations using this method are reviewed. Furthermore, optimization algorithms are discussed. A numerical fully functional code is developed for nonlinear cross section, element and 2D frame analysis, utilizing different finite elements and is verified against existing EIM programs. As a proof of concept, the method is applied on selected examples using this code on cross section and element level. For the former one a comparison is made with standard procedure, by employing the equilibrium equations within the constrains. The validation of the element level was proven by a theoretical solution of an arch bridge and finally, a truss bridge is optimized. Most of the principle examples are chosen to be adequate for the everyday engineering practice, to demonstrate the effectiveness of the proposed method. This study implies that with further development, this method could become just as competitive as the conventional structural optimization techniques using the Finite Element Method.}, subject = {Strukturoptimierung}, language = {en} } @phdthesis{Mai, author = {Mai, Luu}, title = {Structural Control Systems in High-speed Railway Bridges}, issn = {1610-7381}, doi = {10.25643/bauhaus-universitaet.2339}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20141223-23391}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {147}, abstract = {Structural vibration control of high-speed railway bridges using tuned mass dampers, semi-active tuned mass dampers, fluid viscous dampers and magnetorheological dampers to reduce resonant structural vibrations is studied. In this work, the addressed main issues include modeling of the dynamic interaction of the structures, optimization of the parameters of the dampers and comparison of their efficiency. A new approach to optimize multiple tuned mass damper systems on an uncertain model is proposed based on the H-infinity optimization criteria and the DK iteration procedure with norm-bounded uncertainties in frequency domain. The parameters of tuned mass dampers are optimized directly and simultaneously on different modes contributing significantly to the multi-resonant peaks to explore the different possible combinations of parameters. The effectiveness of the present method is also evaluated through comparison with a previous method. In the case of semi-active tuned mass dampers, an optimization algorithm is derived to control the magnetorheological damper in these semi-active damping systems. The use of the proposed algorithm can generate various combinations of control gains and state variables. This can lead to the improvement of the ability of MR dampers to track the desired control forces. An uncertain model to reduce detuning effects is also considered in this work. Next, for fluid viscous dampers, in order to tune the optimal parameters of fluid viscous dampers to the vicinity of the exact values, analytical formulae which can include structural damping are developed based on the perturbation method. The proposed formulae can also be considered as an improvement of the previous analytical formulae, especially for bridge beams with large structural damping. Finally, a new combination of magnetorheological dampers and a double-beam system to improve the performance of the primary structure vibration is proposed. An algorithm to control magnetorheological dampers in this system is developed by using standard linear matrix inequality techniques. Weight functions as a loop shaping procedure are also introduced in the feedback controllers to improve the tracking ability of magnetorheological damping forces. To this end, the effectiveness of magnetorheological dampers controlled by the proposed scheme, along with the effects of the uncertain and time-delay parameters on the models, are evaluated through numerical simulations. Additionally, a comparison of the dampers based on their performance is also considered in this work.}, subject = {High-speed railway bridge}, language = {en} } @article{VuBacLahmerZhangetal., author = {Vu-Bac, N. and Lahmer, Tom and Zhang, Yancheng and Zhuang, Xiaoying and Rabczuk, Timon}, title = {Stochastic predictions of interfacial characteristic of polymeric nanocomposites (PNCs)}, series = {Composites Part B Engineering}, journal = {Composites Part B Engineering}, pages = {80 -- 95}, abstract = {Stochastic predictions of interfacial characteristic of polymeric nanocomposites (PNCs)}, subject = {Angewandte Mathematik}, language = {en} } @article{VuBacLahmerKeiteletal., author = {Vu-Bac, N. and Lahmer, Tom and Keitel, Holger and Zhao, Jun-Hua and Zhuang, Xiaoying and Rabczuk, Timon}, title = {Stochastic predictions of bulk properties of amorphous polyethylene based on molecular dynamics simulations}, series = {Mechanics of Materials}, journal = {Mechanics of Materials}, pages = {70 -- 84}, abstract = {Stochastic predictions of bulk properties of amorphous polyethylene based on molecular dynamics simulations}, subject = {Angewandte Mathematik}, language = {en} }