Fracture Behavior and Strength of Stepped-Lap Bonded Joint with Adhesive Resin Under Tensile Loading.

Nonlinear fracture behavior of stepped-lap bonded joints is studied. The joints used have adherends of eight kinds of metals : three types of carbon steel, and four types of aluminum alloy and brass. The joints also have various thicknesses, lap lengths and step numbers. The effect of Young's modulus and yield strength of adherend material on the joint strength is calculated by means of elasto-plastic finite element method analysis. It is found that the strength of the joint which yields at an adherend corner is nearly equal to the yield strength of the adherend material, because the displacement of the adhesive layer increases abruptly after the adherend yield, and exceeds the layer's deformation capacity. The joint strength diagrams obtained by the strength prediction method applying our adhesion criteria show good agreement with the experimental results for all the present joins having various dimensions and materials.