Experiment and finite element study on static and fatigue behaviour of wide single lap joints with semi-circular defect

The use of adhesively bonded joints is increasing in aeronautical industrial applications due to its high strength-to-weight ratio and excellent stress transfer. Failure of composite bonded joints under fatigue loading occurs when a crack in the joint grows to a length that significantly reduces joint strength. However, it is difficult to accurately predict the crack growth rate in adhesive joints when subjected to cyclic loading due to the presence of defects in the adhesive. Several types of defect could occur in adhesive bonds, which could be generated by inadequate joint preparation during the fabrication procedure, accidental impact in service, etc., all of which reduce the joint quality and influence the joint strength. It is therefore important to understand the joint behaviour under cyclic loads when these defects are present in a structural joint.