Nonlinear buckling analysis of laminated composite curved panels constrained by Winkler tensionless foundation

This article addresses structural analysis of laminated composite cylindrical panels resting on tensionless foundation under axial compression. The problem is inherently and highly nonlinear. The governing equations are derived based on classical shell theory and principle of minimum total potential energy. Major contributions of this paper consider the effects of curvature and composite material properties in deriving energy-based governing equations. The numerical results show that ignoring initial curvature of reinforcing panels for modeling columns having cross sections of curved boundaries would cause that the buckling load would be estimated less than that of actual value. Further, the influence of tensionless foundation on the uni-lateral buckling behavior of panels is severely dependent on effective parameters such as central angle, aspect ratio, thickness, and the degree of foundation modulus. In addition, increasing the number of panel layers, keeping the thickness constant, and choosing an appropriate ply angle for fibers, might increase impressively the influence of tensionless foundation on the buckling load. Moreover, the effects of parameters like aspect ratio, thickness, central angle, the number and angle of plies, lamination scheme, material orthotropy and foundation modulus on buckling load are investigated. The results are compared with case studies, whenever available in the literature.