Numerical simulation of mode-II fracture of CFRP with toughening interlayer using bilinear cohesive zone model

The effect of interfacial toughening porous non-woven fabric (PNF) on the Mode-II fracture toughness (G_IIC) of carbon fiber reinforced polymer is studied by performing end notched flexure tests. The PNF with a thickness of 10 ìm is selected as the interleaf material, which is modeled by the bilinear cohesive zone model. The vertical displacement of loading points and the corresponding force are measured. The influences of the cohesive shear strength and G_IIC of the toughening interlayer on the mechanical response of composites are studied. The main results are obtained as follows. The peak load increases with the increase of the cohesive shear strength, but the increasing amplitude is gradually reduced. Once the delamination propagates steadily, the influence of the cohesive shear strength can be neglected, and at the moment, G_IIC of toughening interlayer plays a leading role. Furthermore, the greater G_IIC of toughening interlayer is, the greater G_IIC of composites and peak load are.