ABSTRACT
Composite structures are subjected to a variety of loading conditions during their service life. Under service conditions, composite structures develop matrix cracks, fiber–matrix debonds, fiber fractures, fiber pull-out, and delaminations. These effects, which cause permanent loss of stiffness and strength within the layer and hence in the laminate, are termed failures. When the failure is at the micro level, it is termed damage. For example, the microcracks observed within a layer constitute damage. As these microcracks grow in size and number, they coalesce and develop into debonds, resulting in a reduction of the load–carrying capacity of the laminate. In order to determine the load–carrying capacity and service life of a composite structure, it is necessary to predict the initiation and evolution of damage.
