Effects of element type on accuracy of microstructural mesh crystal plasticity finite element simulations and comparisons with elasto-viscoplastic fast Fourier transform predictions

In this work, we performed massive crystal plasticity finite element (CPFE) simulations to reveal the effects of element type on the accuracy of predicted mechanical fields and overall response over explicit periodic grain structure meshes of polycrystalline Cu during simple tension (ST), simple shear (SS), and a strain path change from ST to SS. Post-processing of the results provided a list of guidance for effective CPFE modeling of explicit microstructures. First, it was confirmed that quadratic tetrahedral elements (C3D10) are the most suitable for CPFE modeling owing to their accuracy, efficiency, and flexibility to describe complex geometries intrinsic to microstructures. Moreover, these elements predicted the overall response between the stiff linear hexahedral (C3D8) and compliant quadratic hexahedral (C3D20) elements. Next, quadratic hexahedral elements with reduced integration (C3D20R) arose as the second choice for CPFE modeling owing to their accuracy and computational efficiency but these elements generally require more memory than C3D10 elements. These elements were also effective in relaxing the issue of volumetric locking intrinsic to C3D20 elements. The issue could not be eliminated by involving C3D20H or C3D20RH hybrid elements with constant pressure. Finally, corresponding simulations of the same explicit grain structure represented in voxel-based formats using elastoviscoplastic fast Fourier transform (EVPFFT) full-field verified the overall response but predicted the local fields to deviate with plastic strain for all element types.