Multiple Cracking in Angle-Ply Composite Laminates

Abstract

The stress field in a cracked [(±θ°) n2/(90°) n2] s angle-ply fibre-reinforced composite laminate is solved by using Fourier transforms and dual integral equation formulation. The (90°) n1 sublaminate is characterized by periodically distributed multiple transverse intralaminar cracks. The stress intensity factor at each crack tip and the crack-induced interfacial stresses are calculated. Both are found to be significantly influenced by the closeness of the crack tip to the bimaterial interface, the crack spacing and ply angle θ of the constraining sublaminates. The variation of the SIF explains the physical mechanisms behind constrained cracking in composite laminates, while the perturbation of the interfacial stress field caused by the transverse cracks reveals that as the cracks approach the bimaterial interface, there is a considerable increase in interfacial stresses. The crack driving force and the crack-induced interfacial stresses decrease considerably when the multiple cracks are densely distributed. From the design point of view, the results also suggest that by a proper choice of ply angles in angle-ply laminates the crack growth in the individual lamina can be greatly retarded.