Mesoscale thermal-mechanical analysis of impacted granular and polymer-bonded explosives

• Investigating the effect of crystal anisotropy and microstructural heterogeneity on mesoscale thermal-mechanical responses of GXs and PBXs based on a crystal plasticity model.
• Quantifying the interaction between an anisotropic crystal phase and an isotropic polymer binder phase under different loading conditions.
• Relating the mesoscale thermal-mechanical responses to impact sensitivity of explosives.

Localized deformation within energetic materials under impact loading may lead to the formation of hot spots, which can cause initiation or detonation of energetic materials. In this work, the thermal-mechanical response of cyclotetramethylene-tetranitramine (HMX) based granular explosives (GXs) and polymer-bonded explosives (PBXs) under impact loading has been investigated using finite element software ABAQUS. A series of three-dimensional mesoscale calculations is performed at impact velocities from 100 m/s to 500 m/s using a crystal plasticity constitutive model for HMX crystals that accounts for nonlinear, anisotropic thermoelasticity and for crystal plasticity. For PBX simulations, a viscoelasticity model is used for the polymer binder. Results show that the average and localized stress and temperature field, which are greatly affected by crystal anisotropy and polymer binder, of GXs are larger than those of PBXs. Qualitative agreement with Pop Plots from the experiments shows that GXs are more sensitive than PBXs.