@misc{Wolff2005, type = {Master Thesis}, author = {Wolff, Sebastian}, title = {Implementation und Test eines Optimierungsverfahrens zur Loesung nichtlinearer Gleichungen der Strukturmechanik}, doi = {10.25643/bauhaus-universitaet.727}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111215-7271}, school = {Bauhaus-Universit{\"a}t Weimar}, year = {2005}, abstract = {In displacement oriented methods of structural mechanics may static and dynamic equilibrium conditions lead to large coupled nonlinear systems of equations. In many cases they are solved iteratively utilizing derivatives of Newton's method. Alternatively, the equations may be expressed in terms of the Karush-Kuhn-Tucker conditions of an optimization problem and, therefore, may be solved using methods of mathematical programming. To begin with, the work deals with the fundamentals of the formulation as optimization problem. In particular, the requirements of material nonlinearity and contact situations are analyzed. Proximately, an algorithm is implemented which utilizes the usually sparse structure of the Hessian matrix, whereby particularly the convergence behaviour is analyzed and adjusted. The implementation was tested using examples from statics and dynamics of large systems. The results are verified considering the accuracy comparing alternative solutions (e.g. explicit methods). The potential areas of application is shown and the efficiency of the method is evaluated.}, subject = {Nichtlineare Optimierung}, language = {en} } @misc{Ullrich2005, type = {Master Thesis}, author = {Ullrich, Carmen}, title = {Dynamische Analyse der Sprottetalbr{\"u}cke}, doi = {10.25643/bauhaus-universitaet.726}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111215-7268}, school = {Bauhaus-Universit{\"a}t Weimar}, year = {2005}, abstract = {Die vorliegende Arbeit besch{\"a}ftigt sich mit der dynamischen Analyse der Sprottetalbr{\"u}cke infolge aufgetretener Asphaltsch{\"a}den. Sie beinhaltet die Erstellung eines FE-Modells, der Darstellung der theoretischen Grundlagen der Dynamik sowie die Auswertung von berechneten Eigenformen und Asphaltspannungen unter Ber{\"u}cksichtigung der derzeit g{\"u}ltigen Normen.}, subject = {Finite-Elemente-Methode}, language = {de} } @phdthesis{Most2005, author = {Most, Thomas}, title = {Stochastic crack growth simulation in reinforced concrete structures by means of coupled finite element and meshless methods}, doi = {10.25643/bauhaus-universitaet.725}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20051219-7623}, school = {Bauhaus-Universit{\"a}t Weimar}, year = {2005}, abstract = {The complex failure process of concrete structures can not be described in detail by standard engineering design formulas. The numerical analysis of crack development in concrete is essential for several problems. In the last decades a large number of research groups have dealt with this topic and several models and algorithms were developed. However, most of these methods show some difficulties and are limited to special cases. The goal of this study was to develop an automatic algorithm for the efficient simulation of multiple cracking in plain and reinforced concrete structures of medium size. For this purpose meshless methods were used to describe the growth of crack surfaces. Two meshless interpolation schemes were improved for a simple application. The cracking process of concrete has been modeled using a stable criterion for crack growth in combination with an improved cohesive crack model which can represent the failure process under combined crack opening and crack sliding very well. This crack growth algorithm was extended in order to represent the fluctuations of the concrete properties by enlarging the single-parameter random field concept for multiple correlated material parameters.}, subject = {Gitterfreie Methode}, language = {en} }