Fatigue damage characterization and life prediction in carbon fiber reinforced plastic composites.

Abstract

Fatigue damage is one of the most unwelcome failure categories encountered in modern engineering components. Recent advent of Carbon fiber reinforced plastic composites in advanced engineering components and structures such as the present-day advanced aircrafts, marine, and other high performance structures has made it essential for properly characterizing fatigue damage process and developing reliable fatigue life prediction methodologies for these materials. In the present study fatigue damage mechanisms have been investigated in three classes of Carbon-Carbon Fabric Reinforced Plastic Composites. Both destructive and nondestructive techniques such as X-Ray Radiography, Optical Microscopy, Edge Replication and Scanning Electron Fractography have been used to characterize the fatigue damage in these composites. It is shown that the fatigue damage in carbon fabric reinforced composites is a complex, combined and interactive damage process between several damage mechanisms such as delamination, fiber fracture, matrix cracking, fiber-matrix debonding etc. An analytical model used for carbon fiber composite life prediction based on stiffness degradation during cyclic loading has been employed to the Plain-Weave Carbon-Carbon Fabric composites. A reasonably good correlation has been obtained between the analytically determined fatigue lives and the observed fatigue lives of the Carbon-Carbon Fabric Reinforced Plastic Composites.