Defect and Damage Characterization in Composite Materials

摘要

Defects may be introduced in composites during processing and fabrication. They include contaminants, porosity, inclusions, delaminations, and nonuniform fiber and matrix distributions. Damage induced in service under loading and environmental variations includes matrix cracking, delamination, fiber breakage, and dispersed defects, such as matrix ageing and degradation. A variety of nondestructive evaluation methods have been used for composites, but the most effective and practical ones are ultrasonic and radiographic methods. These methods can be supplemented by others, such as acoustic emission, interferometric, and wave propagation techniques. The sensitivity and effectiveness of such NDE methods are discussed in connection with three applications: thick composites, metal-matrix composites, and fatigue damage.