Numerical Predictions of Progressive Damage Evolution in Particulate Composites

Abstract

A method is presented for calculating stresses and strains in a loaded particulate composite structure (specimen) as damage initiates and grows. Load is incrementally applied to a numerically simulated specimen. For every load increment, a finite element method model is used to calculate the composite stresses and strains at each point. A micromechanical model uses the composite strains to calculate the stresses and strains in the composite's component materials, the particles and matrix. A damage model uses the matrix strains to determine values for local matrix damage, and to set reductions in the stiffnesses of damaged matrix material regions, each of which is proportional to the associated damage value. At damaged locations, the micromechanical model uses the reduced matrix stiffnesses to calculate reduced composite stiffnesses. All reduced matrix and composite stiffnesses calculated during a load increment are used in the next load increment.

Matrix strain values are set which determine damage initiation, growth, and saturation. Damage saturation indicates matrix material failure, and for saturation the composite stiffness approaches zero. At a specimen point, a matrix crack will form or extend when the point becomes saturated with damage. Numerical simulation predictions are presented, and compared to experimental data. Plots are included showing stress and strain variation, and crack growth.