Shared Memory OpenMP Parallelization of Explicit MPM and Its Application to Hypervelocity Impact

摘要

The material point method (MPM) is an extension of particle-in-cell method to solid mechanics. A parallel MPM code is developed using FORTRAN 95 and OpenMP in this study, which is designed primarily for solving impact dynamic problems. Two parallel methods, the array expansion method and the domain decomposition method, are presented to avoid data races in the nodal update stage. In the array expansion method, two-dimensional auxiliary arrays are created for nodal variables. After updating grid nodes in all threads, the auxiliary arrays are assembled to establish the global nodal array. In the domain decomposition method, the background grid is decomposed into some uniform patches, and each thread deals with a patch. The information of neighbor patches is exchanged through shared variables. After updating nodes in all patches, their nodal variables are assembled to establish the global nodal variables. The numerical tests show that the domain decomposition method has much better parallel scalability and higher parallel efficiency than the array expansion method. Therefore, a parallel computer code, MPM3DMP, is developed based on the domain decomposition method. Finally, MPM3DMP is applied to a large-scale simulation with 13,542,030 particles for obtaining the high-resolution results of debris cloud in hypervelocity impact.