Characterization of Stiffness Loss in Crossply Laminates with Curved Matrix Cracks

Abstract

Experimental evidence has shown that in crossply laminates numerous matrix cracks often become curved with respect to the plane normal to the laminate plane when three or more 90° plies are stacked in succession. This phenomenon produces damage dependent stiffness losses in both the axial and out-of-plane directions which are strongly dependent on the curved crack state. The authors have constructed a general model for predicting stiffness loss as a function of damage in composite laminates, and the current paper seeks to model this stiffness loss. The model predictions are compared to experimental results for axial stiffness and finite element results for out-of-plane stiffness, and it is shown that the model is accurate in predicting this stiffness loss due to curved cracks.