Boundary Element Analysis of Elastic Stress Distribution in Cracked FRP under Mode I Loading

Mesomechanical analysis of the elastic stress distribution near the tip of a delamination crack in fiber-reinforced plastics (FRP) was conducted using the boundary element method. FRP composites were modeled by a two-dimensional laminated structure composed of an isotropic matrix and orthotropic fiber. A mode I crack was induced in the matrix parallel to the fiber direction. The stress intensity factor, K1, and the energy release rate, G1, were calculated for the above inhomogeneous model and compared with those for a homogenized model. For long cracks, the energy release rate for the inhomogeneous model was equal to that obtained for the homogeneous model. For short cracks, the energy release rate was larger for the inhomogeneous model than for the homogeneous model. The characteristics of the elastic stress distribution ahead of the crack tip in the matrix were compared with the stress distribution for the homogeneous model.