Anisotropic peridynamic simulation of dynamic response of PBX containing polycrystalline HMX under low velocity impact

Numerical modeling of non-shock ignition of polymer-bonded explosive (PBX) is a challenging yet significant research topic in terms of PBX safety. This study develops a novel mechanical-thermal-chemical coupled peridynamic (PD) model comprising anisotropic dynamic response of polycrystalline HMX (octahydro-1,3,5,7-tetranitro-1,2,3,5-tetrazocine) crystals in PBX. Unlike prior simulation approaches that assumed isotropic mechanical properties of HMX, the proposed model can capture the dynamic anisotropic response characteristics of HMX. The dynamic damage, temperature rise evolution, and ignition response of cylindrical PBX constrained by steel structure under low velocity impact are systematically analyzed by this calculation model. The calculation results reveal the relationship between dynamic damage and stress wave dynamics of PBX under structural constraints, as well as the relationship between damage and temperature rise distribution in PBX. Moreover, a new clustering analysis method for hotspot identification is put forth. The simulation results reveal the physical evolution processes of the formation, growth, and coalescence of the hot spots. The estimation of the critical ignition time of PBX under low velocity impact can be achieved by combining hotspot information and ignition threshold curve. The current study can promote understanding of dynamic damage, hotspot nucleation, and evolution associated with the non-shock ignition behavior of PBX.