Tensile strength of CFRP cross-ply laminates containing transverse cracks

The effect of transverse cracks on the ultimate tensile strength (UTS) was experimentally and analytically studied for carbon fiber reinforced plastic (CFRP) cross-ply laminates. For coupon specimens of various cross-ply stacking sequences, quasi-static tensile tests were carried out and transverse cracks were observed. The experimental results showed that the measured fiber bundle strength of 0° ply was almost constant, which indicated that transverse cracks had little influence on the notch sensibility of the bundle strength. Then, we proposed a new numerical model based on the finite element method to investigate the damage extension to the fracture. This model considered the elastoplastic behavior of epoxy matrix and the fiber breakages. Using this model, we applied a Monte-Carlo method to the damage extension simulation. It was found that the plastic region at the tip of the transverse crack reduced the stress concentration due to the crack, and that the bundle strength was barely affected by transverse cracks.