Stress analysis and strength evaluation of scarf adhesive joints subjected to static tensile loadings

The stress distributions in scarf adhesive joints under static tensile loadings are analyzed using three-dimensional finite-element calculations. The effects of adhesive Young’s modulus, adhesive thickness and scarf angle in the adherend on the interface stress distributions are examined. As the results, it is found that the maximum value of the maximum principal stress occurs at the edge of the interfaces. The differences in the interface stress distributions between the 2-D and the 3-D FEM results are demonstrated. It is also observed from the 3-D FEM results that the maximum value of the maximum principal stress is the smallest when the scarf angle is around 60 degree, while it is around 52 degree in the 2-D FEM when the singular stress at the edges vanishes. In addition, the joint strength is estimated using the interface stress distribution obtained from the FEM calculations. For verification of the FEM calculations, experiments were carried out to measure the strengths and the strains in the joints under static tensile loadings using strain gauges. Fairly good agreements were observed between the 3-D FEM and the measured results for strains. Therefore, for the joint strength, the results remain conservative.