Simulation of high explosive explosion using adaptive material point method

Numerical simulation of high explosive explosion problems is a big challenge to traditional numerical methods because explosion usually involves extremely large deformation and multi-material interaction of different phases. Recently developed meshfree methods show much advantages over mesh-based method for problems associated with very large deformation. Some of them have been successfully applied to impact and explosion problems, such as smoothed particle hydrodynamics (SPH). Similar to SPH, material point method (MPM) is an efficient meshfree particle method solving continuum problems. With combination of the advantages of Eulerian and Lagrangian methods, MPM is a promising numerical tool for solving large deformation problems, such as high explosive detonation and consequent demolishment to the structures. A three dimensional MPM code, MPM3DPP, is developed by using C++ programming language. With adaptive particle splitting scheme proposed in this paper, MPM3DPP is capable of simulating different explosion problems. Johnson-Cook material model is implemented in order to take strain rate effect and thermal softening effect into consideration. Mie-Grüneisen equation of state is used to treat volumetric response of metal under high pressure. Jones-Wilkins-Lee (JWL) equation of state is used for describing the expansion process of detonation products. Artificial viscosity is added to pressure term to stabilize and capture the shock wave. The MPM3DPP code is validated by simulating TNT slab detonation and shock tube problem, and then is used to simulate different explosion problems including explosively driven flyer problem and shaped charge problem. The computational results are in good agreement with empirical formula and experimental results.