Hexagonal close-packed (hcp) metals show a deformation behavior, which is quite different from that of materials with cubic crystalline structure. As a consequence, rolled or extruded products of magnesium and its alloys exhibit a strong anisotropy and an unlike yielding in tension and compression. In this work, the microstructural mechanisms of deformation in pure magnesium are modeled by visco-plastic constitutive equations of crystal plasticity. Single crystals and textured polycrystals are analyzed numerically. By means of virtual mechanical tests of representative volume elements mesoscopic yield surfaces are generated. The linking of micro-and mesoscale provides a procedure for the simulation of the yielding and hardening behavior of arbitrarily textured solids with hcp structure such as extruded bars or rolled plates.

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Compared with conventional fracture mechanics concepts, constitutive equations which account for local damage of the material have the advantage that the corresponding material parameters for ductile fracture can be transferred between different specimen geometries. They will hence be able to describe the physical effect of constraint on the tearing resistance in a natural way. The paper shows the capabilities of the GURSON model in predicting JR-curves for different specimen geometries under static and dynamic loading with one set of material parameters. It is shown how these parameters can be determined from the numerical simulation of simple tensile tests. Problems and open questions are discussed and perspectives for future applications are given.