Damage Tolerance of Composites

This chapter discusses two issues: What is damage tolerance? Why is this issue a concern? To answer these questions and to develop an understanding of the damage tolerance (DT) issue, it is necessary to define the material systems to which a DT definition can be related. In the case of metals versus composites, a key overriding issue related to DT is the difference in the formation of damage and the resulting damage mechanisms. Most high-strength graphite-epoxy composite laminates lack ductile behavior at high strains which is characteristic of metals. The composite material constructions, which are the main focus of the monograph: polymer matrix composites, metal matrix composites, ceramic matrix composites, carbon/carbon, and hydrids. To be effective, the next generation of composite material systems must be designed to provide the requisite in-plane structural properties. The damage sources lead to one of the most significant types of problems associated with continuous fiber polymeric composites: their inherent tendency to delaminate.