On the Prediction of Mechanical Behavior of Particulate Composites Using an Improved Modulus Degradation Model

New micromechanical models for the prediction of particulate composite mechanical behavior have been developed. The models use an energy balance concept to account for nonlinear behavior due to particle debonding and incorporate a composite modulus prediction routine based on an improved Mori-Tanaka method. This method permits particle interaction effects to be taken into account and allows the stiffness matrix for voids or vacuoles to be explicitly stated in the model. To demonstrate the characteristics of the improved Mori-Tanaka method, comparisons with 2-phase and 3-phase modulus data were made. The micromechanical models developed for void and vacuole formation were evaluated against available mechanical behavior data. Comparisons showed that the model derived for vacuole formation predicted the mechanical behavior correctly for a range of composites which contained inclusion volume fractions ranging from 0.2 to 0.4. The inability of the models to predict the initial stress-strain behavior of a composite containing a volume fraction of 0.22 of well bonded particles suggests nonlinear matrix effects need to be included in the present model formulation.