Evaluation of Composite Curing Stresses

A recently developed approach to predict the initial stress field within a composite laminate after fabrication processing is examined in some detail. In this approach, the material response is assumed to be elastic with temperature-dependent properties. With the introduction of the concept of a stress-free temperature, it is shown that this position is defensible by use of deformation measurements on unsymmetric angle-ply units. Implications concerning the influence of the curing stress field on initial damage level (first-ply failure) are studied analytically. The predictions indicate a marked effect of curing stress in certain laminates. The consequences of combined moisture and thermal effects on initial damage level also are discussed.