ANALYSIS OF PARTICULATE COMPOSITE BEHAVIOR-BASED ON NONLINEAR ELASTICITY AND MODULUS DEGRADATION THEORY

A micromechanical model for the analysis of particulate mechanical beh aviour is presented. Non-linear effects were introduced in the model b y a non-linear elastic description of the matrix and through a modulus degradation routine. The first part of the study used the experimenta l data from a range of glass bead/HTPB composites to back-calculate mo del parameters. The results showed that the model gave a good represen tation of the processes believed to control mechanical behaviour. Thes e processes include partial particle debonding and progressive debondi ng from the largest to smallest particles throughout the strain histor y. The second part of the study examined the sensitivity of the model results to small changes in the adjustable input parameters. The resid ual bond in a debonded particle was found to have a dominating effect on the calculated results. Based on the sensitivity results, ''best gu ess'' interaction and debonding parameters were selected to examine th e predictive capability of the model. In most cases, the predicted com posite stresses were within 10% of the experimental data. Dilatation w as usually over-predicted. The results showed that the model was capab le of predicting the mechanical behaviour as long as suitable values f or critical stress and adhesion energy were available.