Evaluation of Mode II Fracture Toughness in Glass Cloth/Epoxy Laminates by Rail-Shear Test Method

Rail-shear tests were carried out on the glass cloth/epoxy laminates, and then the mode II fracture toughness value, K_IIin, was obtained as the pre-crack length, 2a/W, was altered from 0.2 to 0.45. In addition, the spread of damage was obtained under simulation by the finite element method and then compared with the experimental results. The following results were obtained; (1) In this test method, the recommendable pre-crack length existed in order to obtain the fracture toughness value. (2) The material used in this study was assumed to be a homogeneous anisotropic material of a tetragonal system, and then the finite width correction factor of the specimen geometry was calculated. Consequently, KII in became almost constant in the range of 2a/W=0.25~0.45. (3) The spread of damage was simulated by the finite element method, and it was found that the analytical result agreed with the initial failure process obtained in the experiment. In addition, the J_II value was calculated from the path integral, and discussed.