Shear Buckling of Rectangular Composite Plates with Two Concentric Layups

A method to calculate the buckling load of rectangular composite plates with two concentric layups under shear is presented. The method is based on a polynomial expansion of the out of plane displacement of the plate and energy minimization. The resulting generalized eigenvalue problem for the buckling load is solved using the bisection method. The predictions of the present method are found to be in excellent agreement with the special cases of isotropic plates or anisotropic plates with a single layup. For the case of two concentric layups, the method is found to be in good agreement with finite element predictions. The use of concentric layups in composite plates promises to significantly reduce their weight meeting the same buckling load requirements.