抄録
Three-dimensional meso-mechanical analysis was conducted by the finite element method (FEM) in order to determine the elastic stress distribution around a crack tip in fiber-reinforced plastics (FRP). FRP plates were modeled as a typical 'one-fiber slice' model, represented by the fiber-resin model. The fibers were arranged in a square array with a fiber volume fraction of 0.60 Matrix crack is parallel to the fiber direction and is subjected to model I loading. The stress intensity factor, K_<lm>, and the average energy release rate was calculated for the above inhomogeneous FRP, and compared with those for a homogeneous FRP. For the long crack, the average energy release rate for the inhomogeneous FRP was equal to that obtained for the homogeneous FRP. For long crack, the matrix-stress distribution ahead of delamination can be divided into three regions: Region I, II and III (IIIa, IIIb) in the order of increasing distance from crack tip. The matrix-sterss in Region I had a singularity of 1/√r, but was smaller than that of the homogeneous FRP. Region IIIa has a singularity, too. But stress intensity factor of Region III was not equal to that of Region I. Region II was transitional region from Region I to IIIa.
