Closed-form solution for the postbuckling behavior of long unsymmetrical rotationally-restrained laminated composite plates under inplane shear

This paper studies a closed-form solution for the nonlinear postbuckling behavior of long unsymmetrical rotationally-restrained laminated composite plates subjected to shear load. The analysis method described can be applied to the postbuckling behavior of stiffened plates under limitations of the local buckling mode, in which the portion of panel with two stiffeners is modeled as a thin plate with two edges restrained with torsion springs. Nondimensional parameters are introduced in order to cover a wide class of material properties and laminate configurations. An appropriate mode shape function is proposed for the postbuckling process, under the assumption that the buckling mode remains unchanged as the deflection increases. Substituting the shape function into the governing equations, an precise closed-form solution for the load–deflection relationship is derived using the Galerkin method. To conclude, stiffened composite plates with representative unsymmetrical laminate configurations are used as analytical models for a comparison of the closed-form solution. The finite element simulation demonstrates the closed-form solution’s ability to predict postbuckling behavior with high computational efficiency.