A micromechanical model for predicting combined damage of particles and interface debonding in PBX explosives

In order to clarify the roles played by material constituents to the mechanical response of plastic-bonded explosives (PBXs), a micromechanical model is presented by combining a continuum damage model and a discrete damage model within the framework of a finite element code. Debonding of particle/matrix interface was modeled by the viscoelastic cohesive zones considering damage irreversibility which was representative of the effects of polymer binders in the composite system. Key damage and fracture process of PBX9501 explosive material under quasi-static uniaxial tension and compression were investigated. The simulated rate-dependent stress-strain curves for PBX9501 under compression agree well with experimental results given by Gray et al. (1998) [Gray III, G.T., Ida, D.J., Blumenthal, W.R., Cady, C.M., Peterson, P.D., 1998. High- and low-strain rate compression properties of several energetic material composites as a function of strain rate and temperature. In: Proceedings of the 11th Detonation Symposium. Snowmass Village, Colorado] which justifies the present model. The significant rate dependence of PBX explosive captured by the present model is mainly attributed to the cohesive law's rate-dependence. Simulated Brazilian compression results show complicated interactions and larger relative movement among particles. Wavy fracture path tends to form in the aggregate model in Brazilian disc, while the cracking path is roughly vertical to loading direction in uniaxial tension specimen.