Hard particle effects on frictional heating of PBX surrogates characterized by high spatiotemporal resolution

Abstract

A tiny hot spot can start a devastating explosion. Among potential mechanical stimuli such as drop, impact, and puncture, localized frictional heating is regarded as one of the most probable, especially in the presence of hard particles. However, due to its transient and micro-meso scale characteristics, the transient temperature rise has yet to be characterized by in situ instruments. As a result, though detailed cognition has been reached, direct characteristic observation was still pending. In this work, an in situ temperature measurement system for transient frictional heating was developed by integrating a high-speed infrared thermography system on a split Hopkinson pressure bar, with a spatial resolution of 12.5 μm and a temporal resolution of 1 μs. A PBX surrogate with mechanical properties similar to those of genuine PBX is employed for in situ observation of dynamic frictional heating, while the effects of hard particles and substrate type are compared under dynamic friction loading. Based on the experimental results, a localized heating formation mechanism governed by substrate strength was proposed, providing an in situ temperature measurement experimental method and phasic understanding for the investigation of localized frictional heating induced by hard particles.