Application of granular mechanics to the analysis of solid propellants

Abstract

In this paper a theoretical method is developed for analyzing the mechanical behavior of granular solid propellant materials. The granular nature of the material is specifically taken into account and, the analysis allows for a media composed of non-uniformly sized particles with random stacking configuration. The voids between the particles are assumed to be filled with an elastic, homogeneous binder material. Three types of internal forces are assumed to be acting; the normal and tangential contact forces between the granular particles and, the elastic stresses in the binder. The paper consists of three main parts. First a model is developed to represent a general granular medium. Subsequently, in the second part this model is used to analyze the response of a granular medium to hydrostatic pressure loading. Finally the stress-strain relations are derived for a general loading condition. Because of the presence of the non-conservative frictional forces between the granular particles, the deformation of such a medium depends on the loading history. Consequently the stress-strain relations are in a differential, or incremental form.