Investigation of Surface Skidding Response of PBX 9501 and PBX 9502

Abstract

Introduction: Assess the hazards of handling polymer bonder explosives(PBX) for the case of skidding with grit particles in the frictional interface. High explosive (HE) materials tested: PBX 9501 and 9502. High melting point materials at the skidding interface between HE and a substrate is known to increase the probability of ignition by creating hot spots not subject to reduced heating from the melting of HE material. Skidding occurred at peak forces of 6-26 kN normal force, and 0.6-3.4 kN of frictional force. Velocities for skidding range from 5-30 m/s, see figure 7. Sparse amounts of 300 μm silica grit is applied loosely to the HE surface before testing. Previous works have tested ignition by grit. Testing parameters include angle of impact, drop height, grit size, grit density, substrate material. This study focuses on pre ignition conditions and detailed thermal imaging of the frictional interface. Conclusions: Temperature hot spots were observed at high points in HE surface topology. These high points may be created by grit particles. Since these points impact first high frictional work is concentrated and quickly increases temperature. Small amounts of grit do not affect the overall frictional force but do concentrate the frictional work to create hot spots.