On the creep of thin shells of revolution including geometrical nonlinearity and asymmetric properties of the material

Many new materials (light-metal-alloys, composites etc.) are showing typical signs of creep under moderate loads at a high temperature level. The creep behaviour can be anisotropic, although the material has an isotropic behaviour in its original state. Furthermore the reaction on tensile and compressive loads are different, what is called asymmetry of the material behaviour. This material property is not considered in the models of the classical creep mechanics. This material behaviour has to be considered in the design of highly loaded structural elements, which are used in areas with improved safety-requirements (e.g. power-plants). Most of these elements can be modelled as thin shells, Therefore a calculation concept for thin rotational shells under axisymmetrical load is introduced, which allows the consideration of these special creep behaviour as well as geometrical nonlinearities (small strains, but displacements in the order of magnitude of the shell thickness). The possibilities of the calculation concept and the material procedure are shown by some numerical examples.