Quasi‐Static compaction studies for DDT investigations. Ball Propellants

Abstract

AbstractA Quasi‐Static compaction study has been performed on a number of ball propellants to complement studies of dynamic compaction behaviour, shock sensitivity, and deflagration‐to‐detonation transition (DDT) behaviour that are currently being conducted for high porosity granular beds of such materials. These ball propellants are of interest because they are simple, unfilled propellant systems. Many of them have particles which are spherically shaped, a geometry that facilitates numerical modeling of the DDT process. Four Olin ball propellants, designated as WC 140, TS 3660, Type A Fluid, and Winchester #231, have been investigated in detail by simultaneously measuring applied force, transmitted force, and porous bed displacement. An average axial compressive force per unit radial cross‐sectional area of the solids in the porous bed, called the „intragranular stress”︁, is then calculated as a function of percent theoretical maximum density for values ranging initially from 44%–58%, to final values greater than 85%, depending on the ball propellant. A microscopic examination was performed on a number of recovered samples that had been compacted to various stress levels to identify the nature and extent of plastic deformation and fracture in the propellant particles and to provide insight into compaction mechanisms and associated pore structures in the compacted porous bed. A brief discussion relating these considerations to hot spot formation and DDT behaviour is also presented.