Materials and Mechanics Analyses of Durability Tests for High-Temperature Polymer Matrix Composites

Models of the environmentally-induced degradation of composite materials and the effect of this degradation on composite laminate behavior are presented. Although the models are not sufficiently mature for predictive design use, they provide insights into the mechanisms of degradation of composite materials. The models are used to study test methods frequently used to assess composite durability, including weight loss, shrinkage, and mechanical property degradation testing. It is found that even simple tests of material undergoing environmentally induced degradation are difficult to interpret. In particular, the spatial nonuniformity of degradation converts originally simple specimens into complex structures with non-uniform chemical and mechanical states. Consideration of this complexity is vital to the full understanding of the results of such tests.