A micromechanical model will enable improved predictions of the stress-strain responses and fracture of carbon-phenolic laminates under rapid heating conditions. In contrast to current methods, which model structural behavior of ablatives using composite-material (macro) data as input, the new model would predict composite behavior from constituent-material (micro) data. Advantages would include a reduced need for full testing of each new composite made with the same fiber and matrix and an improved understanding of the physical phenomena underlying composite behavior in rapid-heating environments. This model would differ from conventional micromechanical representations of laminates by incorporating the development of porosity and pore-gas pressure during heating, by treating matrix strain capabilities in excess of 15 percent, and by including prediction of gas permeabilities. Phase I is aimed at establishing feasibility of a computer implementation of a model in a suitable form for use with (or within) finite-element structural analysis codes. Issues to be addressed include the mathematical formulation and the types of experimentation needed to define constituent input data.An analytical tool for predicting the behavior of composites during heating would have wide applicability, as heating is used in many composite manufacturing processes and there is a continual economic incentive to increase heating rates without damaging the material. The software developed could be marketed commercially as an add-on to general-purpose structural analysis codes.carbon-phenolic composites, rapid heating, thermomechanical response, fractureSTATUS: Phase I Only
