Interlaminar stress analysis of composite laminates with internal ply-drop

A stress function-based variational method is used to determine the thermal stresses near the dropped plies. The method is based on expanding stress functions in terms of harmonic series in the out-of-plane direction. Using the complementary strain energy principle, the stresses satisfying the traction free conditions of tapered laminates are obtained. As the number of initial out-ofplane basis functions increase, stress concentration near dropped plies are predicted well. The proposed method is relatively simple and efficient at the prediction of interlaminar stress concentration neax ply-drops.