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

TL;DR

This study investigates how mesh density and boundary conditions influence the accuracy of grain-averaged elastic strain predictions in crystal plasticity finite element simulations, aiming to optimize computational efficiency.

Contribution

It systematically analyzes the effects of mesh density and boundary conditions on prediction accuracy, establishing minimum simulation requirements for reliable results.

Findings

Accurate grain-averaged elastic strain predictions need about 250 elements per grain.

A buffer of at least three grains is necessary between the region of interest and control surfaces.

Optimal simulation conditions balance accuracy with computational cost.

Abstract

Combined high-energy X-ray diffraction microscopy (HEDM) and crystal plasticity finite element (CPFE) modeling studies have emerged as a preferred paradigm to shed insight into the evolution of elasticity and plasticity at the intragrain scale of polycrystals. In particular, far-field HEDM measures the deformation response of upwards of thousands of individual grains simultaneously in situ during mechanical loading, though measurements are primarily limited, however, to the average state of each grain -- i.e., the grain's full strain tensor, crystallographic orientation, spatial location and volume. CPFE is utilized to shed information on the intragrain deformation response, via the sub-discretization of each grain into many finite elements, though the direct point of comparison to HEDM remains the grain-averaged response. We thus seek to find the minimum simulation conditions necessary to provide consistent grain-averaged predictions in an attempt to limit computational cost. In this study, we perform a suite of simulations and systematically study 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.