Analysis of shear-deformable composite beams in postbuckling

The nonlinear response of composite beams modeled according to higher-order shear deformation theories in postbuckling is investigated. The beam ends are restrained from axial movement, and as a result the contribution of the midplane stretching is considered. The equations of motion and the boundary conditions are derived using Hamilton's principle. The shear deformation effect on the critical buckling load and static postbuckling response is introduced using classical, first-order, and higher-order shear deformation theories. This paper presents an exact solution for the static postbuckling response of a symmetrically laminated simply supported shear-deformable composite beam. The shear effect is shown to have a significant contribution to both the buckling and postbuckling behaviors. Results of this analysis show that classical and first-order theories underestimate the amplitude of buckling while all higher-order theories, considered in this study, yield very close results for the static postbuckling response.