Abstract
An analytical model for predicting the matrix crack induced stiffness reduction of FRP laminates with off-axis cracked plies is developed. The constitutive equations for a cracking ply are first proposed with the assumption of the equivalence between a cracking ply and a work-softening material. Then they are incorporated into the classical lamination theory to describe the damage evolution in FRP laminates with off-axis cracked plies. The energy release rate in a cracking ply is adopted as the criterion for crack formation, and the number of cracks is predicted by dividing the cumulative released energy in a cracked ply by the released energy due to single crack formation. With the predicted number of cracks, the variation of the laminate stiffness with the crack density is evaluated. The uniaxial tension test is performed on GFRP [0/θn/0] laminates, and the elastic modulus in the loading direction is measured at five different crack density. The experimental results are compared to the corresponding predictions of the elastic modulus for three different center ply angles.
