Material Point Method for Impact and Explosion Problems

Behavior of impact and explosion is complicated and usually involves large deformation and multi- material interaction of different phases. Failure and fragmentation of structure caused by impact or explosion also need to be considered. Simulation of impact and explosion problem requires a powerful numerical tool. The material point method, MPM, combines the advantages of Eulerian and Lagrangian description of motion. It eliminates the drawbacks of numerical difficulties associated with mesh distortion and element entanglement in Lagrangian and with the advected quantities in Eulerian description. Therefore the MPM is well suitable to the impact and explosive problems, which involves large deformation and interaction of different materials. A three dimensional material point method code, MPM3D, is developed. The linear hardening plasticity, Johnson-Cook plasticity and high explosive material model are implemented. Three kinds of equation of state (EOS) are implemented to calculate the pressure of different materials under extreme load. They are Gruneisen EOS for solid material, JWL EOS for explosive products, linear polynomial EOS for air. Numerical examples including Taylor bar impact, debris cloud and cylinder test are given to investigate the performance of MPM3D, which show that MPM is much more efficient than FEM and SPH in simulating hypervelocity impact and explosion problems, especially in large scale problems.