Stress bridging in particulate composites and calculation of G23 in particulate composites

High energy materials are commonly used as solid rocket motors propellants. The properties of HE materials can be determined experimentally; however, the hazards associated with experiments on these materials, as well as the costs, make this approach unattractive. The simulations of these materials require techniques that can bridge submicron scales and engineering scales. Micromechanics provides such techniques. The objective of this research is to investigate the effects of stress bridging on predicting the effective properties of high energy materials group. The research focused on polymer bonded explosives (PBXs), since detailed numerical simulations of PBXs are computationally expensive. The generalized method of cells was explored for this research and its predictions of elastic moduli with and without stress bridging. The results show that stress bridging affects the estimated properties considerably. The generalized method of cells without stress bridging is shown to underestimate the elastic moduli of the polymer bonded explosives. Micromechanics analysis requires that the fundamental material properties of the constituents are known initially. The composite material properties can be determined experimentally by testing actual composite specimens. However, in recent years, more and more attention has been given to the development of the analytical and numerical models for predicting composite material properties from the properties of the constituent materials and their relationship to each other. The other part of this research is to identify the Representative Volume Element (RVE) and the boundary conditions for calculation of transverse shear modulus (G23) and then compare the results to the other classical micromechanics solutions. The results show that the proposed approach for identifying the Representative Volume Element (RVE) and the boundary conditions predict as accurately as the other classical micromechanics solutions.