A 3D combined particle-element method for intense impulsive loading computations involving severe distortions

• CPEM provides favorable characteristics of both finite elements and meshless particles.
• CPEM allows for accurate simulations of mild structural deformations as well as severe distortions.
• CPEM computations can be run with elements only, particles only, or conversion of distorted elements into particles.

This article presents a Combined Particle-Element Method (CPEM) for 3D intense loading computations that include severe distortions. It includes the numerical algorithms and example computations. The advantages of this method are that the lower-strained particles (stress points) are computed with a fast and accurate finite-element formulation, and the higher-strained particles are computed with a meshless-particle formulation that can handle severe distortions. Furthermore, the meshless-particle algorithm (with MLS strain rates and weak-form forces) is consistent and does not exhibit tensile instabilities. It is also well suited for conversion of finite elements into variable-connectivity meshless particles because the conversion does not require deletion of elements and addition of particles. Instead there is simply a branch point based on equivalent plastic strain. The basic approach can also be used for the element algorithm only or the particle algorithm only.