Design of thermoplastic and elastomeric components by means of finite element simulations
This thesis describes some capabilities of the finite element analysis during the lay-out process of thermoplastic and elastomeric components. Approaches are presented, which show how the computations can be performed in a material-adequate manner, thus becoming a valuable supplement for the conventional design in practice.For short-glass fibre reinforced thermoplastics, simulation of the locally observed fibre orientations are of major importance for the evaluation of the mechanical and thermo-mechanical behaviour of components.
Appropriate micro- and macro-mechanical approaches and the application of the continuum theory take the anisotropic material behaviour into account and relate it to the locally computed main fibre orientation directions as a result of the mould filling simulation.The examples carried out under consideration of the local (linear) anisotropic material behaviour show that the integration of the process simulation and structural analysis is possible even for complex components and likewise necessary to improve result quality.
A second focus of this thesis is given by the mechanical and thermal analysis of elastomer components. The presented investigations for the evaluation of quasi-static load cases allow for the statement, that the application of material laws, based on the strain energy density concept, leads to acceptable results even in three-dimensional finite element analyses. For a complex spring design of an engine mount the force-displacement characteristic as well as the observed deformation can be determined with good accuracy. Among the investigated material laws, the approach of KILIAN is convincing due to excellent reproduction of the basic experiments up to high extension ratios. This is similar with the approach of OGDEN.The prediction of the temperature development in dynamically loaded rubber components is of great practical interest. Therefore, a calculation concept is presented for the uncoupled solution of the mechanical and thermal problem.
A third section of the thesis deals with the design of experiments (DOE) method in conjunction with the capabilities of modern calculation software.For the example of cylindrical snap-fit hinges it shows that it is an effective method for a more methodical, lay-out of technical components compared with the conventional variant calculations.
Special attention should be paid to the fact that non-attributive design variables, which have an influence on the shape of the component, can easily be taken into consideration. Compared with the evolution strategy, the statistical experimental design has the great advantages that, first, the interaction effects become transparent, and secondly, the obtained correlations can be stored and easily re-used by means of model equations.Lesen Sie die deutsche Zusammenfassung auf Kunststoffe.de
Integrative Simulation, mould filling simulation, structrual analysis, FEA, short-fibre reinforced components, fibre orientation, anisotropic part properties, micro mechanics, Halpin-Tsai, elastomeric components, material model, Mooney-Rivlin, Kilian, Ogden, loss energy, temperature distribution, design of experiments, model-based geometry optimization
Institute / chair: Fakultät für Maschinenwesen der Rheinisch-Westfälischen Technischen Hochschule Aachen
Technical consultant for expert services: Prof. Dr.-Ing. Dr.-Ing. E.h. Walter Michaeli (Betreuer), Prof. Dr.-Ing. Georg Menges
Publication year: 1991
Provider: Fakultät für Maschinenwesen der Rheinisch-Westfälischen Technischen Hochschule Aachen
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