Effective interlaminar shear moduli in composites containing transverse ply cracks

The effective interlaminar shear modulus for [θ/90m°]S and [±θ/90m°]S laminates containing transverse cracks through the middle 90m° layers are determined analytically. The cracks are assumed to be evenly spaced and to extend across the entire laminate width. The θ   ply and 90m° ply cluster are treated as a single homogeneous plate, while the ±θ plies are treated as a single laminated plate. The two plates are connected through continuity of displacements and tractions at the interface. In addition to determining the effective shear modulus, a singularity analysis is presented in conjunction with a [0°/90°]S bi-directional laminate. The singularity is then utilized in conjunction with the laminate model to look at the interlaminar shear stress near the crack tip along the 0°/90° interface. Numerical results are compared to both a finite element analysis and to a previously developed self-consistent model.