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 of carbon steel, four of aluminum alloy and one of 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 elastoplastic finite-element 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 currently available joints having various dimensions and materials.