1999 Volume 42 Issue 4 Pages 521-529
In particle or short-fiber reinforced composites, cracking or debonding of the reinforcements is a significant damage mode because the damaged reinforcements lose load carrying capacity. This paper deals with a theory of the reinforcement damage in discontinuously-reinforced composites and its application. The composite with progressive cracking damage contains intact and cracked reinforcements in a matrix. To describe the load carrying capacity of the cracked reinforcement, the average stress of a broken ellipsoidal inhomogeneity in an infinite body which was proposed in the previous paper is introduced. An incremental constitutive relation of the composites with progressive cracking damage of the reinforcements has been developed based on Eshelby's equivalent inclusion method and Mori and Tanaka's mean field concept. This damage theory can describe not only cracking damage but also debonding damage of the reinforcements by modifying teh load carrying capacity of damaged reinforcements. Influence of the reinforcement damage on the stress-strain response and elastic stiffness of the composites is discussed. It is noted that tha full-debonding damage gives the lower limit of the stress-strain relation of the composite with progressive reinforcement damage.