Post-buckling behavior of imperfect laminated composite plates with rotationally-restrained edges

The nonlinear governing equations of rotationally-restrained laminated composite plates with imperfection are presented by the Galerkin method, and they are solved by employing the Newton-Raphson method for the post-buckling analysis. The considered laminates are symmetric, and they are loaded in pure in-plane shear or combined in-plane shear and compression. The deformation shape function of the restrained plates is obtained through a linear combination of vibration eigenfunctions of simply supported and clamped beams along either the longitudinal or transverse direction of plates. The validity study shows that the presented method is effective for performing the nonlinear analysis of laminates with all four edges elastically-restrained against rotation. A parametric study is conducted to evaluate the effect of rotational spring stiffness, material properties, and fiber orientation under pure in-plane shear as well as the loading ratio under combined shear and compression on the nonlinear static and post-buckling behavior of rotationally-restrained laminates. The proposed solution for nonlinear static analysis of rotationally-restrained composite plates with imperfection is accurate and effective, as demonstrated by the comparisons with the predictions by the finite element analysis, and combined with the discrete plate analysis technique, it can be potentially applied to post-buckling analysis of FRP structural shapes.