Interlaminar stresses in general thick rectangular laminated plates under in-plane loads

Three-dimensional multi-term extended Kantorovich method (3-D multi-term EKM) is employed to investigate analytically the interlaminar stresses near free edges of finite length general composite laminates subjected to axial and shearing loads. Using the principle of minimum total potential energy, three systems of coupled ordinary differential equations are obtained. Then an iterative procedure is established to achieve analytical solution. Laminates with finite dimensions are considered and full three-dimensional stresses in the interior and the boundary-layer regions are calculated. The results obtained from this theory are compared with those of analytical results existing in the literature or with those obtained by the finite element method when there exist no available results. It is found that interlaminar stresses have excellent agreements with those obtained by layerwise theory in the interior region and near the free edges of both finite and long laminates. Convergence study of the method reveals that the 3-D multi-term EKM converges within only four terms of trial functions and the single-term EKM is not able to estimate the local interlaminar stresses near the boundaries of laminates. Finally, the power of the present approach in obtaining the interlaminar stresses in finite length thick laminated plates with general lay-ups is examined.