Mechanical properties and damage evaluation of a UK PBX

Abstract

This study outlines the mechanical properties of an explosive material tested at AWE Plc, Aldermaston, Reading, Berkshire, UK. The material is a composite polymer bonded explosive of energetic binder and HMX crystals, referred to as EDC37. An understanding of material deformation under a range of conditions and age, along with damage quantification, is required to predict mechanical behaviour throughout service life. The mechanical testing of EDC37 was performed alongside simultaneous recording of Acoustic Emission (AE) data at static strain rates and temperatures. The simultaneous testing was intended to focus on the link between mechanical properties and damage evolution. Forty tests were performed in various configurations, consisting of live explosive material and an inert simulant. Evaluation of the Acoustic Emissions was performed and data grouped into categories of activity. It was concluded that AE confirms mechanical behaviour associated with damage accumulation in compression (crack initiation and growth, crack closure and/or HMX twinning) and crack damage (binder HMX debonding and coalescence) above a threshold stress or time in tension. The activity seen is different between tensile and compressive modes and needs to be taken into consideration in Finite Element Models.