Effect of 3D grain structure representation in polycrystal simulations

Simulation results from finite element models using two types of 3D polycrystal geometric representations, one with a voxel representation and stair-stepped grain boundaries and the other with smooth grain boundaries, are compared. Both models start with a periodic grain structure representation, which is in the form of a regular, rectangular 3D array of points, where each point is assigned an orientation. The voxel representation is obtained by simply sampling the array of grid points on a coarser regular grid with a prescribed resolution and forming a voxel centered at each grid point, which is assigned the grain orientation from the sampled grid point. The voxel representation may be meshed directly by decomposing each voxel into finite elements. In the second case, a method is presented that extracts geometric topology information for a grain structure with smooth, flat grain boundaries from the discrete grain structure representation. From the geometric topology information, a finite element mesh is created. The two representations are then D. M. Pyle · J. Lu · D. J. Littlewood · A. M. Maniatty (B) Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180-3590, USA e-mail: [email protected] D. M. Pyle e-mail: [email protected] J. Lu e-mail: [email protected] Present Address: J. Lu SBM Atlantia, Houston, TX, USA D. J. Littlewood e-mail: [email protected] Present Address: D. J. Littlewood Sandia National Laboratories, Albuquerque, NM, USA subjected to large strain deformations, and the simulation results and efficiencies are compared. The macroscopic behavior, overall texture evolution, and statistical distribution of stress and slip are found to be nearly identical for both models. However, noticeable differences are observed in the misorientation distribution within grains and the smoothness of the stress field. The voxel representation is found to be more efficient because of the uniform finite element mesh.