Multiscale numerical investigation of ratchet growth damage effects in PBX 9502

This paper presents results of numerical experiments conducted on the high explosive PBX 9502 to investigate how recently observed grain-scale damage mechanisms of ratchet growth [1] affect uniaxial compression measurements. Simulations are multiscale in the sense of directly resolving grains, pores, cracks, and grain-interfaces based upon scanning electron microscope (SEM) images of damaged and undamaged samples. The combined finite-discrete element method (FDEM) is utilized to resolve both grain-scale microfracture and elastoplastic deformation of solid grains. Pristine (undamaged) and damaged microstructures are compared in simulation of unconfined compression tests of the same material from the literature. The simulation results show the observed microscale mechanisms of damage, specifically microfracture predominantly around and sometimes through grains and crack-associated pore growth, can well-explain the effective degradation of strength and stiffness observed in the laboratory measurements. image

Automated summary

This paper presents numerical experiments on the high explosive PBX 9502 to investigate the impact of recently observed grain-scale damage mechanisms on uniaxial compression measurements. The simulations directly resolve grains, pores, cracks, and grain-interfaces based on SEM images of damaged and undamaged samples. The results show that the observed microscale damage mechanisms can well explain the degradation of strength and stiffness observed in the laboratory measurements.