A PREDICTIVE MODEL FOR THE MECHANICAL-BEHAVIOR OF PARTICULATE COMPOSITES .1. MODEL DERIVATION

A method for predicting the highly nonlinear stress-strain behavior and dilatation induced by cavitation of highly filled particulate composites from constituent properties has been developed. The approach presented uses a variation of linear elasticity throughout and has no adjustable parameters, unlike the methods currently used, which require large numbers of fitting factors and complicated nonlinear analyses. An energy balance derived from the first law of thermodynamics calculates critical strain values at which filler particles will debond when subjected to deformation. Repeated calculations of critical strain values using re-evaluated material properties accounting for the damage caused by debonding give very nonlinear stress-strain and dilatation curves. Experimentally observed dependencies on particle size, filler concentration, adhesion, and matrix and filler properties are correctly predicted. The method can be generalized for any state of stress or particle shape. Comparisons of experimental data with the model results give good agreement.