Sensitivity of grain-averaged elastic strain and orientation predictions on the mesh density and boundary conditions in crystal plasticity finite element simulations

We analyze the simulation conditions for proper prediction of grain-average elastic strains and (re)orientations. Experimentally, these quantities can be measured in 3D by far-field HEDM, for upwards of thousands of individual grains simultaneously in situ during mechanical loading, allowing for direct comparison with crystal plasticity finite element (CPFE) simulations. Since CPFE simulations typically use a sub-discretization of each grain into many finite elements, we seek to find the minimum simulation conditions necessary to provide consistent grain-averaged predictions for comparison with experimentally measured values, in an attempt to limit computational cost. Through a suite of simulations, we systematically analyze the effects of mesh density and boundary conditions, and consider different materials. We discuss these results and show that accurate prediction of grain-averaged elastic strains in a given region of interest typically requires a mesh with 250 elements per grain on average and a buffer layer of at least three grains between the region of interest and the control surfaces.