Oxidation resistant carbon-carbon composites: the effect of temperature dependent matrix material properties on laminate response

Abstract

The structural analysis of carbon-carbon (C-C) composites is a research area of increasing importance. As the use of the materials expands towards more demanding aerospace applications, it is of critical importance to understand the laminate mechanics specific to carbon-carbon composite laminates. Specifically, the materials of interest in this research are oxidation resistant carbon-carbon composites. These material systems include a protection scheme to prevent the catastrophic oxidation of the structure in oxygen rich environments in excess of 450 OC. A common protection scheme includes the use of external oxidation barrier coatings in conjunction with internal particulate oxidation inhibitors. The goal of this research is to gain an understanding of the influence of the oxidation of the inhibitor particles on the mechanical properties of the matrix material, as well as the thermomechanical performance of the laminate. This investigation encompasses two development phases. In the initial phase, the oxidation of the inhibitor particles and its effect on the temperature dependent material properties of the inhibited matrix material are analyzed. The temperature dependent matrix material properties developed are then used as model input in two dimensional representations of the through the-thickness region of a carbon-carbon laminate. Two different through-the-thickness representations are considered. The through-the-thickness models are subjected to a variety of longitudinal and transverse mechanical and thermomechanical loads. Results indicate that the assumed material transformation of the matrix material has little effect on the longitudinal or axial performance of the model. The material transformation, however, is shown to affect the transverse model response.