Simple and efficient interlaminar stress analysis of composite laminates with internal ply-drop

A stress function-based variational method is developed to investigate the interlaminar stresses near the dropped plies. The present method is based on expanding stress functions in terms of harmonic series to the out-of-plane direction. The stresses satisfying the traction free boundary conditions of tapered laminates are obtained by the complementary strain energy principle. Stress concentrations near the dropped plies are predicted well as the number of initially assumed out-of-plane stress functions is increased. The proposed method is relatively simple and efficient in the prediction of interlaminar stresses near the dropped plies. Therefore, it is expected that the proposed method can be used in the parametric study of the preliminary design stage of tapered composite laminates.