2013 Volume 49 Issue 9 Pages 320-330
The interface stress distributions in scarf adhesive joints with dissimilar adherends under static bending moments 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 E1/E2 between the dissimilar adherends, adhesive Young's modulus, the scarf angleθand 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 aroundθ=60°, the singular stress at the edges of the interfaces is minimal in the 3-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. The difference in the maximum value of the normalized maximum principal stress which occurs at the edge of the interface with higher Young's modulus is substantial between the 2-D and the 3-D FEM results. In addition, it is found that the joint strength 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 measured strains are in fairly good agreement with those obtained from 3-D FEM calculations. Also, the measured 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 slightly larger in the case where the width is held constant
