Investigation of finite element mesh independence in rate dependent materials

Crystal plasticity theory is commonly used in finite element analyses to predict large strain ductility in single crystal and polycrystal deformation. In the rate-dependent formulation of the theory it is possible, for cases of simple deformation, to achieve an analytical solution that is independent of any effects due to the finite element mesh spacing. In this study single crystal and polycrystal models were subjected to alternative loading conditions. The effect of the mesh density on the generation of strain localisations and shear bands was investigated with regard to consistency of results. It was found that, prior to the initiation of a narrow shear band, it was possible to achieve a numerical result independent of mesh spacing. In the larger polycrystal analyses, an element size was identified that enabled the generation of a mesh independent solution. This allowed the accurate prediction of the mechanical behaviour of the model up to, and including, the failure point. The implications of this for small-scale metallic device design are discussed.