Interaction Curves for Composite Laminates Subjected To Biaxial In-plane Loads

In this study, an attempt has been made to incorporate the effect of transverse shear on the stability analysis of moderately thick/very thick composite laminated plates under in-plane compressive loading using a "Simple Higher-Order Shear Deformation Theory" based on four unknown displacement functions (u₀, v₀, w_b, w_s) instead of five which is commonly used in most of the higher-order theories. The finite element method is employed to study the initial buckling load of laminated plates. The change in initial buckling response of thick rectangular anti-symmetric laminates with respect to the fiber orientation angle has been studied. The interaction curves (between N_xand N_yfor different parameters of the laminates) are studied in detail. The interaction curves for N_xand N_yare either linear or piecewise linear. There are some combinations of biaxial in-plane loads for which laminates with different lay-up sequences have the same initial buckling loads.