@inproceedings{Montag1997, author = {Montag, U.}, title = {A New Efficient Concept for Elasto-plastic Simulations of Shell Responses}, doi = {10.25643/bauhaus-universitaet.436}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111215-4364}, year = {1997}, abstract = {For the analysis of arbitrary, by Finite Elements discretized shell structures, an efficient numerical simulation strategy with quadratic convergence including geometrically and physically nonlinear effects will be presented. In the beginning, a Finite-Rotation shell theory allowing constant shear deformations across the shell thickness is given in an isoparametric formulation. The assumed-strain concept enables the derivation of a locking-free finite element. The Layered Approach will be applied to ensure a sufficiently precise prediction of the propagation of plastic zones even throughout the shell thickness. The Riks-Wempner-Wessels global iteration scheme will be enhanced by a Line-Search procedure to ensure the tracing of nonlinear deformation paths with rather great load steps even in the post-peak range. The elastic-plastic material model includes isotropic hardening. A new Operator-Split return algorithm ensures considerably exact solution of the initial-value problem even for greater load steps. The combination with consistently linearized constitutive equations ensures quadratic convergence in a close neighbourhood to the exact solution. Finally, several examples will demonstrate accuracy and numerical efficiency of the developed algorithm.}, subject = {Schale}, language = {en} } @inproceedings{GabbertGrochlaKoeppe1997, author = {Gabbert, U. and Grochla, J. and K{\"o}ppe, H.}, title = {Dynamic-explicit finite element simulation of complex problems in civil engineering by parallel computing}, doi = {10.25643/bauhaus-universitaet.425}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111215-4259}, year = {1997}, abstract = {The paper deals with the simulation of the non-linear and time dependent behaviour of complex structures in engineering. Such simulations have to provide high accuracy in the prediction of deformations and stability, by taking into account the long term influences of the non-linear behaviour of the material as well as the large deformation and contact conditions. The limiting factors of the computer simulation are the computer run time and the memory requirement during solving large scale problems. To overcome these problems we use a dynamic-explicit time integration procedure for the solution of the semi-discrete equations of motion, which is very suited for parallel processing. In the paper at first we give a brief review of the theoretical background of the mechanical modelling and the dynamic-explicit technique for the solution of the semi-discrete equations of motion. Then the concept of parallel processing will be discussed . A test example concludes the paper.}, subject = {Tragwerk}, language = {en} } @inproceedings{Tzanev1997, author = {Tzanev, D.}, title = {Entwurf eines objektorientierten Modells zur Analyse von Schalentragwerken}, doi = {10.25643/bauhaus-universitaet.439}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111215-4397}, year = {1997}, abstract = {In der vorliegenden Arbeit werden dickwandige Schalentragwerke unter statischen Belastungen betrachtet. Die Schale besteht aus verschiedenen Zonen und in jeder Zone wird die Schalenmittelflaeche mittels eines eigenen Geometriegleichungssystems definiert. Das Verzerrungsfeld hat allen 6 unabhaengigen Komponenten unter der Annahme, dass die Querschnittsfasern, die normal zu der Mittelflaeche der unbelasteten Schale sind, geradelinig bleiben. Ein dreidimensionales isoparametrisches finites Element wird vorgeschlagen. Die Berechnung wird mit der Hilfe der Makroelemententechnik durchgefuehrt. In der Arbeit werden die wesentliche Parameter der Schalengeometrie, sowie auch entsprechendes Anteil von Klassen des konstruktiven Modells, definiert. Ein konstruktives Informationsmodell und ein FEM-Informationsmodell, werden entwickelt. Die Informationsverbindungen zwischen den beiden Modellen werden definiert. Diese objektorientierten Modelle werden in Programmiersprache Microsoft Visual C++ v.4.0 unter Windows 95 implementiert. Als numerisches Beispiel wird ein Bogenmauertragwerk betrachtet.}, subject = {Bogenstaumauer}, language = {de} } @inproceedings{Skrinar1997, author = {Skrinar, Matjaz}, title = {A simple FEM Beam Element with an Arbitrary Number of Cracks}, doi = {10.25643/bauhaus-universitaet.428}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111215-4287}, year = {1997}, abstract = {To fulfil safety requirements the changes in the static and/or dynamic behaviour of the structure must be analysed with great care. These changes are often caused by local reduction of the stiffness of the structure caused by the irregularities in the structure, as for example cracks. In simple structures such analysis can be performed directly, by solving equations of motion, but for more complex structures a different approach, usually numerical, must be applied. The problem of crack implementation into the structure behaviour has been studied by many authors who have usually modelled the crack as a massless rotational spring of suitable stiffness placed at the beam at the location where the crack occurs. Recently, the numerical procedure for the computation of the stiffness matrix for a beam element with a single transverse crack has been replaced with the element stiffness matrix written in fully symbolic form. A detailed comparison of the results obtained by using 200 2D finite elements with those obtained with a single cracked beam element has confirmed the usefulness of such element.}, subject = {Finite-Elemente-Methode}, language = {en} }