Computational Micromechanics of Damage Initiation and Growth in Functionally Graded Composites

The purpose of this work is to investigate the effect of microstructures of functionally graded particle reinforced composites on the strength and damage resistance in the materials. In order to study the microstructure-strength and microstructure-darnage resistance relationships of graded composites with metal matrix and ceramic inclusions, a series of numerical mesomechanical experiments has been carried out. The tensile stress-strain curves, fraction of failed particles versus applied strain curves, and stress and damage distributions at different stages of loading were determined for different generic (artificially designed) graded microstructures and compared. It was shown that the flow stress and stiffness of composites increase and failure strain decreases with decreasing property gradient (i.e., when the particles become more localized in some material regions). The damage growth in particles in graded composites initiates within particles, which are located in the transition zone between the zone of high particle density and the particle-free regions.