THERMOELASTIC PROPERTIES OF COMPOSITE LAMINATES WITH TRANSVERSE CRACKS

Different models based on variational analysis are compared with respe ct to the thermo-elastic properties of cross-ply laminates with transv erse cracks in the 90-degrees-layer. This approach, pioneered by Hashi n, applies the principle of minimum complementary energy to describe t he stress state in a cross-ply laminate with transverse cracks. Apart from material data, only laminate geometry data and stress distributio n assumptions are required. The model developed in the present study c ontains stress distribution assumptions that are closer to reality tha n previous models. Non-uniform stress distributions are included throu gh-the-thickness of both the 0-degrees- and the 90-degrees-layers. An important result is the improved agreement with stiffness reduction da ta. As expected from the nature of the model, predictions generally pr ovide lower bounds to the stiffness of the cracked laminate. However, at high crack densities, this is not the case. This additional stiffne ss reduction at high crack densities indicates the presence of new dam age types, such as branched cracks and local delamination.