Stress Distribution in Single Lap Joints with a Cracked Composite Adherend—Part I: Single Lamina Adherends

Abstract

The effect of a crack in the overlap region of a single step lap joint is studied on the shear distribution in the adhesive layer. Each adherend is considered to be a lamina with unidirectional fibers aligned in the direction of the applied load. Crack location is selected to be in the top adherend, in the form of cut fibers and matrix bays. The shear-lag model is used to derive the equilibrium equations which are then solved using eigenvector expansion. Additionally, a finite element model of the lap joint was prepared and solved using ANSYS. The results of the two methods perfectly match each other. The effects of crack location along the length of the overlap, crack size, edge cracks, adhesive thickness, and type of fibers were investigated on the shear distribution in the adhesive layer and its corresponding peak values. The effect of dissimilar adherends was also investigated on the adhesive shear stress distribution. According to the results, in the presence of a crack, the peak adhesive shear stress is very susceptible to adhesive thickness and type of fibers used in each adherend. Other factors also influence the peak shear stress to some degree.