Effect of Voids Arrangement on Behavior of PMMA Cellular Materials on Impact Loading

Cellular materials, characterized by their light weight and energy absorbing, etc., have broad potential applications in the fields of loading-path control, explosion and impact protection. In this paper, the discrete element method of lattice-spring model is utilized to simulate the early impact response of PMMA cellular materials with different arrangement models of voids during the impact loading process. The early void collapse failure, stress distribution and particle velocity of materials with various arrangement models are investigated. Our results show that the arrangement of voids affect the particle velocity but not the shock wave velocity. The cracks are germinated in the area near the longitudinal direction of the void, and the failure mode of the void is mainly shear failure. In different arrangement models of voids, there is a phenomenon of shear cracks interpenetrating between the holes, which promotes the compression of the volume. The square lattice and triangular lattice arrangement models prominently slow the stress concentration and plastic deformation rate of voids in the nearby area. The square lattice, triangular lattice, decreasing arrangement and increasing arrangement significantly have a remarkable influence on the flatness of the shock wave front of PMMA cellular materials. The random arrangement is the most effective one to reduce the particle velocity, and the square lattice contributes most to the post-pressure reduction of the wave front.