An interlaminar stress continuity theory for laminated composite analysis

A complete analysis of a new lamination theory presented in a previous investigation for studying the interlaminar stresses in both thin and thick composite laminates is developed. This theory is based on a multiple-layer approach. Hermite cubic shape function is used as the interpolation function for composite layer assembly through the thickness direction. Because of the high-order shape function, the theory can satisfy the continuity of both interlaminar shear stress and interlaminar normal stress exactly on the composite interface. It then is able to obtain the interlaminar stresses directly from the constitutive equations. In addition, because of the high-order interpolation function, the transverse shear deformation is considered in the theory. Accordingly, the theory can be used for both thin and thick composite laminates. In this study, the composite laminates under cylindrical bending studied by Pagano are investigated to verify the new theory. Closed form solutions agree excellently with the elasticity results. A finite element technique based on the principle of minimum potential energy is also used for numerical analysis. The numerical results also show excellent agreement with the exact solution.