Mesoscale simulations of uniaxial compression and shock loading of low porosity granular aluminum/nickel composites

Abstract

Continuum level Material Point Method (MPM) simulations have been carried out on low porosity (around 90% or greater of theoretical maximum density) microstructures of Al/Ni granular composites (Al/Ni). The Al/Ni microstructures were subjected to uniaxial (strain) compressive loading and shock compression up to 25 GPa. The MPM model accounted for frictional heating between grains in addition to plastic work and compressional heating effects. The distributions of stresses and temperature in the composite materials were found to be highly heterogeneous due to the heterogeneous nature of the composite microstructure. The manner in which interfaces between grains were treated (sliding vs. non-sliding) was found to influence both mechanical and thermal responses to loading. Plastic deformation, mechanical work, and grain/grain frictional effects led to modest increases of mean temperature and local hotspots with maximum temperature not higher than 800–850 K for loadings investigated. For all scenarios investigated, heat generation was insufficient to cause local Al melting believed to be a precursor for shock initiation.