p. 639-644
The propagation path of matrix cracks parallel to the fiber direction in continuous fiber-reinforced plastics (FRP) under remote mode I loading was predicted by the stress intensity factors and the nonsingular T-stress, T_m, in a matrix layer. These parameters for two FRP models were calculated by using the two-dimensional boundary element method. One model is the inhomogeneous FRP model which has a laminated structure composed of matrix and fiber, and the other is three-layered FRP model in which a matrix layer is sandwiched between homogenized FRP plates. When the residual stress in the matrix layer is negligible, T_m is negative for typical FRP composites. For long cracks, the absolute value of T_m for the inhomogeneous FRP model is larger than that for the three-layered FRP model, but the sign of T_m for both models is the same. A crack in typical FRP composites is predicted to run along the centerline of the matrix layer because of a negative T_m value and the sign of the mode II matrix stress intensity factor. For long cracks, the propagation path of matrix cracks in inhomogeneous FRP was predictable from two parameters of three-layered FRP model. The effects of the residual stress, material properties, the height of the cracked matrix layer, and the crack length on the crack propagation path were discussed on the basis of the results of the present analysis.
