Continuum Modeling of the Development of Intralaminar Cracking in Composite Laminates

Abstract

Intralaminar cracking in composite laminates has been found to develop as a set of parallel cracks whose average spacing reduces with increasing stress level or with increasing number of cycles of a given stress amplitude. The average crack spacing has been found in some instances to approach a minimum which has been interpreted as saturation or characteristic state. These features of the intralaminar cracking are predicted by the continuum model presented here. The model characterizes the intralaminar cracking by a second–order damage tensor defined on a representative volume element of the cracked laminate and describes the development of this cracking by the rate of the damage tensor. The components of the damage rate tensor are treated as response functions subjected to the initial material symmetry restrictions. An incremental solution to the rate equations shows that the crack density is an exponential function of the strain and displays the experimentally observed characteristics.