Modellierung des mechanischen Verhaltens von Schuettguetern

Describing the behaviour of bulk solids during handling and storage in advanced bulk solid handling devices frequently requires the use of numerical tools (e.g. Finite Element Method). To be able to use those methods advanced constitutive models able to describe effects like the compression characteristics, internal friction, cohesion or rate dependence of the bulk solid have to be applied. In this thesis Kolymbas' hypoplastic model, which describes the stress rate as a function of momentary stress and momentary strain rate, is applied to fine cohesive limestone powder. From experiments with a true biaxial tester a quality criterion is derived, which is used with the 'Evolutionsstrategie', to identify the constitutive parameters of the hypoplastic model. From biaxial tests with a sharp bend the response envelope of the limestone powder is determined experimentally. To describe the behaviour of fine cohesive limestone, the basic version of the hypoplastic model is not sufficient. Therefore two additional state variables are introduced in the constitutive equation. The structure tensor describes the effects of cohesion, the #PSI#-tensor the rate dependence of the material. The structure tensor is a stress like entity, representing the loading history, while the #PSI#-tensior has the dimension of a strain rate. The extended model can describe isotropic yield strenght, relaxation and rate dependence. (orig.)Available from TIB Hannover: RR 5346(23) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman