Failure of adhesive bonded composite lap shear joints with embedded precrack

The effect of cracks embedded in strap adherend on the lap shear joints is presented in this paper. The failure loads and failure modes of specimens with different length of cracks are determined in the experimental study. A non-linear finite element analysis (FEA) is conducted to illustrate the effect of crack and adhesive spew fillet on the stress distribution in the adhesive layer and the energy release rates at both crack tips. An analytical solution is also developed for the lap shear joints with embedded crack. Failure loads of the joints are predicted using the critical energy release rate based and the maximum stress criteria. A good correlation is found between the measured failure loads and those predicted using FEA and analytical models.