HIGH-VELOCITY NONLINEAR DEFORMATION AND FRACTURE OF A DAMAGED MEDIUM WITH INITIAL STRESSES

With account for the degradation of the properties of materials, the nonlinear processes of deformation and fracture in a preloaded three-dimensional solid with a sharp concentrator in the zone of a dissimilar joint under impact are analyzed. A generalized mathematical model of nonlinear interrelated deformation and fracture of damaged polycrystalline media subjected to time-varied thermomechanical effects is presented. The strong nonlinearity of the model is due to large (finite) strains and the strain-rate dependent behavior of media with a variable microstructure. With account for the anisotropic hardening of media and the Bauschinger effect, the corresponding nonlinear boundary value problems are formulated and their solutions are obtained using efficient numerical methods. The viscosity of the medium and the second-order gradients from the internal variables of the system are used to control the correctness of the problem statement. Experimental data are used to test the model. Modeling results are presented.