The effect of interface shock viscosity on the strain rate induced temperature rise in an energetic material analyzed using the cohesive finite element method

In this work, shock induced failure and local temperature rise behavior of a hydroxyl-terminated polybutadiene (HTPB)—ammonium perchlorate (AP) energetic material is modeled using the cohesive finite element method (CFEM). Thermomechanical properties used in the model were obtained from four different experiments: (1) dynamic impact experimental measurements for fitting a viscoplastic constitutive model, (2) in situ mechanical Raman spectroscopy (MRS) measurements of the separation properties for fitting a cohesive zone model, (3) a pulse laser induced particle impact experiment combined with the MRS for measurement of the interface shock viscosity, and (4) Raman thermometry experiments for measurement of HTPB, AP, and HTPB-AP interface thermal conductivity. HTPB-AP interface regions with high density of particles were found to be more susceptible to local temperature rise due to the presence of viscoplastic dissipation as well as frictional heating. The increase in the interface shock viscosity lead to a decrease in both the viscoplastic and frictional dissipation. This resulted in a decrease in the maximum temperature and the density of local regions with a maximum temperature rise within the HTPB-AP microstructure. A power law relation for the decrease in viscoplastic energy dissipation, temperature rise and the density of the local temperature rise with the interface shock viscosity was obtained. (paper)