FEM Stress Analysis and Strength Prediction of Scarf Adhesive Joints withDissimilar Adherends Subjected to Static Tensile Loadings

Abstract

The interface stress distributions in scarf adhesive joints with dissimilar adherends under statictensile loadings are analyzed using two-dimensional and three-dimensional finite element calculations for the two cases where the adhesive length is held constant and where the width of the adherends is held constant. The effects of Young's modulus ratio Ef/E2 between the dissimilar adherends, adhesive Young's modulus, the scarf angle θand the adhesive thickness on the interface stress distributions are examined.In addition, the joint strength is predicted based on the maximum principal stress theory. It is found that when the scarf angle is around θ=60°, the singular stress at the edges of the interfaces is minimal in the 3-D FEM calculations, while the singular stresses vanish for θ=52° in the 2-D FEM calculations. It is noticed that the strength of the joints with dissimilar adherends is smaller than that of the joints with similar adherends.In addition, it is found that the jointstrength decreases as Young's modulus ratio E1/E2 increases. For verification of the FEM calculations,the strains in the adherends and the joint strengths were measured in the experiments. The measuredstrains are infairly good agreement with those obtained from 3-D FEM calculations. Also, themeasured joint strength is fairly consistent with the 3-D FEM results. The difference in the normalized maximum principal stress is small between the two cases while the joint strength is a little bitlarger in the case where the width is held constant.