Impact-induced deformation and ignition related to localized viscous shear flow heating for high-ductility composite energetic materials

Understanding the impact-induced deformation and ignition properties of high-ductility composite ener-getic material (CEM), including high-energy propellants and casted high explosives, is fundamental to the safety design and usage of rockets and warheads and has been a broad concern in the fields of aerospace and defence. In this study, an impact ignition experiment is designed using a Split Hopkinson Pressure Bar to quantitate the continuum deformation and reaction responses of a high-ductility CEM sample undergone periodic impact loading pulses. The relation between macroscopic shear deformation rate and localized viscous shear flow heating, melting, and reaction is further investigated utilizing a macro-mesoscopic thermomechanical model. The results show that CEM sample is severely crushed to 2% of the original thickness and laterally extruded with a high shear rate (-105 s-1). High shear deforma-tion rate contributes to the localized viscous shear flow heating, thereby inducing temperature rise spike (-200 K) and following ignition. Ignition of CEM sample occurs in the third compression pulse because the thinner sample exhibits a high velocity gradient, which causes a high viscous shear flow heating rate.(c) 2022 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

Understanding the impact-induced deformation and ignition properties of high-ductility composite energetic material (CEM) is crucial for the safety design and usage of rockets and warheads. In this study, an experiment and a thermomechanical model are used to investigate the deformation and reaction responses of CEM samples. The results reveal that high shear deformation rate leads to localized viscous shear flow heating, resulting in high temperature rise and ignition.