THERMOELASTIC PROPERTIES OF COMPOSITE LAMINATES WITH TRANSVERSE CRACKS

Different models based on variational analysis are compared with respect to the thermo-elastic properties of cross-ply laminates with transverse cracks in the 90-degrees-layer. This approach, pioneered by Hashin, applies the principle of minimum complementary energy to describe the stress state in a cross-ply laminate with transverse cracks. Apart from material data, only laminate geometry data and stress distribution assumptions are required. The model developed in the present study contains stress distribution assumptions that are closer to reality than previous models. Non-uniform stress distributions are included through-the-thickness of both the 0-degrees- and the 90-degrees-layers. An important result is the improved agreement with stiffness reduction data. As expected from the nature of the model, predictions generally provide lower bounds to the stiffness of the cracked laminate. However, at high crack densities, this is not the case. This additional stiffness reduction at high crack densities indicates the presence of new damage types, such as branched cracks and local delamination.