ELAS3D-Xtal: An OpenMP-accelerated crystal elasticity solver with automated experiment-driven microstructure generation

Abstract: This paper introduces ELAS3D-Xtal, a high-performance Fortran/OpenMP upgrade of the NIST ELAS3D voxel-based finite element solver for computing 3D elastic fields in polycrystals with defects. The code supports crystal anisotropy by precomputing rotated stiffness tensors from user-specified orientations and solves the equilibrium problem with a matrix-free, OpenMP-parallel preconditioned conjugate-gradient (PCG) method using a point-block Jacobi preconditioner. On a single shared-memory multicore PC, OpenMP threading accelerates the baseline CG solver by ~10X, while the block-preconditioned CG solver achieves 53-61X speedup relative to the serial CG baseline for meshes from 100^3 to 500^3 voxels (scaling to domains up to 800^3 voxels). Accuracy is validated against the analytical Eshelby inclusion solution. ELAS3D-Xtal also integrates microstructure construction, including statistically calibrated polycrystal generation via spatial filtering and parallel voxel-to-grain assignment, direct pore insertion from XCT centroid/radius data, and texture assignment. Full-field phase, orientation, and stress outputs are written in HDF5 to enable scalable post-processing and defect-mechanics workflows. Applications are demonstrated for (i) anisotropy-controlled defect-scale stress fields and (ii) LPBF SS316L microstructures with gas, lack-of-fusion, and keyhole pore morphologies.