Analysis of post-buckling and delamination in laminated composite St. Venant–Kirchhoff beams using CZM and layer-wise TSNDT

A layer-wise third order shear and normal deformable plate/shell theory (TSNDT) incorporating a cohesive zone model (CZM) is used to study the initiation and growth of delamination in straight and curved laminated beams. Upon satisfaction of the delamination criteria at a point on the interface between two layers, displacements there of two abutting points on the interface between the two layers are made discontinuous. Delaminations under mode-I, mode-II and mixed-mode static and transient loadings have been studied. All geometric nonlinearities, including the von Karman nonlinearity, are considered. The material of each layer is assumed to be St. Venant–Kirchhoff for which the second Piola–Kirchhoff stress tensor is a linear function of the Green-St. Venant strain tensor. Example problems studied also include delamination growth during axial buckling of a three-layer beam. It is found that the consideration of inertia forces noticeably delays the buckling load and significantly affects the deformed shape of an axially compressed laminated beam.