Degradation in Strength of Laminated Composites Subjected to Intense Heating and Mechanical Loading

An analytical procedure is presented for predicting the loss in integrity of composite structures subjected to simultaneous intense heating and applied mechanical loads. An in tegral part of the method is a nonlinear, two-dimensional, finite difference thermal analysis which considers the effects of surface ablation, re-irradiation losses, and temperature-dependent thermophysical properties. Another important feature of the structural survivability model is a flat-plate finite element code, based on the Mindlin theory, which is coupled to a maximum stress failure criterion. Predictions from the analysis methodology are compared with experimental results obtained on 24, 48, and 96 ply graphite epoxy tension specimens which were spot-irradiated at various intensity levels.