Geometrically nonlinear analysis for unbalanced adhesively bonded single-lap joint based on flexible interface theory

An improved one-dimensional beam model considering simultaneously the effects of interfacial compliance and the large deflection for adherends and overlap is proposed for the unbalanced single-lap joint (SLJ) under tensile loading. Based on the displacement compatibility condition of flexible interface, the governing differential equations that captured the main features of geometrical nonlinearity for the unbalanced SLJ are derived. The present model can obtain closed-form solutions for edge moment factors, transverse deflections and interface stress distributions for the unbalanced SLJ. The compared results between the present model, existing classical models and nonlinear finite element results validate the accuracy of the geometrically nonlinear model. Finally, the influences of Young’s modulus ratio and thickness ratio on the edge moment factors are studied with the present model.