Durability of Woven Polymer Matrix Composites

S. R. Patel, S. W. Case, and K. L. Reifsnider

The use of composite systems as structural materials is growing. Composite systems offer the advantage of being generally lighter and stiffer than traditional structural materials such as metal and wood. However, very little is known about the effects of moisture and temperature on the durability of composite systems. Moreover, testing these materials proves time consuming and expensive. Consequently, a need has grown for life prediction tools that assess the durability and reliability of composite material systems with minimal effort.

Life prediction of composite materials represents a somewhat greater problem than life prediction of metals because failure of metals is defined by a single flaw (e.g., a crack). In composite material systems, defining failure is more complicated since single flaws do not necessarily lead to critical degradation of material properties. In recent years, many investigations have been made into prediction of remaining strength and life of composite materials, leading up to the development of three main types of models: residual strength degradation models, modulus reduction models, and damage tolerance models. However, relatively few studies have been done in which environmental and mechanical degradation processes are simultaneously imposed on material.