Implementation of a mesh-size-independent viscoplasticity damage model through a nonlocal continuum mechanical approach

For the efficient use of solid materials in all kinds of constructive applications, a profound understanding of both the material’s behavior and the damaging processes is necessary. With the wide repertoire of deformation and damage simulation models available today, the estimation of a component’s life expectancy is mainly a matter of assembling the correct approaches and of putting sufficient effort into the characterization of the material (for the identification of the model parameters). The complexity of the assembled model then depends on the complexity of the loading conditions under which the component is to survive. In this thesis, a model is regarded as sufficient if its complexity matches that of the particular application at hand and if it is able to predict a component’s behavior against previously specified requirements. When predicting future damage to a component and calculating its life expectancy in finite element simulations, two common problems are the dependence on mesh size and the overestimated localization of damage. Both phenomena are typically tackled by regularization approaches that enhance damage evolution from a local viewpoint to a nonlocal consideration. The current work builds on a state-of-the-art gradient regularization method, which is applied on a viscoplastic continuum damage model. Thereby the total strain is connected to a micromorphic field variable, which is introduced as an additional degree of freedom. The model development procedure and its implementation is described in detail and simulation results in1D and 3D are presented to demonstrate the regulatory capabilities