Effect of Strain Rate on Mechanical Response of PBX Simulants

Abstract

This paper is concerned with the effect of the strain rate on the mechanical response of polymer-bonded explosive (PBX) simulants at various strain rates ranging from 0.0001 to 3,710 s⁻¹. The mechanical response of PBXs at intermediate and high strain rates is important in the prediction of deformation modes of PBXs in a warhead system which undergoes severe dynamic loads. Inert PBX stimulants, which have analogous mechanical response to PBXs, were utilized for all material tests due to safety reasons. The uniaxial compressive tests at quasi-static and intermediate strain rates ranging from 0.0001 to 100 s⁻¹ were conducted with cylindrical specimens using a dynamic material testing machine (INSTRON 8801) and a developed high-speed material testing machine (HSMTM). A novel experimental method is developed for the uniaxial compressive tests at intermediate strain rates ranging from 10 to 100 s⁻¹. The split Hopkinson pressure bar (SHPB) was used for the uniaxial compressive tests at high strain rates ranging from 1,200 to 3,710 s⁻¹. The pulse shaping technique was adopted for the SHPB tests to minimize wave dispersion and to facilitate stress equilibrium and constant-strain-rate deformation in the specimen. Deformation behavior was investigated using captured images obtained from a high-speed camera. The effect of the strain rate on the mechanical response during the uniaxial compressive deformation is quantitatively investigated from the experimental data at the various strain rates.