A MICROMECHNICS APPROACH TO PREDICTING THE ONSET YIELDING ENVELOPE OF PARTICULATE COMPOSITE MATERIALS

Abstract

Composite materials fail for various reasons and extensive research has been conducted both experimentally and theoretically. However, theoretical prediction of composite failure by yielding seems scarce. Adding reinforcing elements to matrix significantly affects the structural behavior of composite materials. The inserted particles on one hand obstruct the progress of cracks and on the other hand cause stress concentration on the interface of the particle-matrix and eventually influence the ultimate strength of the material. In this research, we study the interface stresses and strength in particulate reinforced composites under uniform mechanical and thermal loading. We theoretically obtain failure envelopes for particulate reinforced composites. This is achieved by estimating the stress field in the matrix phase around a spheroidal particle in an unbounded matrix phase along with the self-consistent approximation that determines the effective elastic modulus of the composite. The failure envelopes are calculated on the basis of the maximum von Mises stress as a function of the applied far-field stresses or heat flow. We also discuss the effect of the particle volume fractions and the particle to matrix stiffness ratios on the interface stresses and ultimate yielding strength. Parametric analysis enables us to predict these envelopes for various loading conditions, volume fractions and particle to matrix stiffness ratios.