On thermal instability of delaminated composite plates

Abstract This paper examines the thermal instability of rectangular delaminated composite plates. A solution procedure is presented based on the third-order shear deformation theory by taking into consideration the von Karman geometrical nonlinearity. The proposed model is capable of analyzing both local buckling of the delaminated base laminate and sublaminate as well as the global buckling of the plate. The thermomechanical properties are temperature-dependent. The nonlinear equilibrium equations, derived by the minimum total potential energy principle, are solved by using the Ritz method along with the Newton–Raphson iterative procedure. Numerical results shed a light on the effects of embedded delamination, stacking sequences, and boundary conditions on the equilibrium path, thermal bifurcation points, buckling mode, in-plane displacement, normal/shear strain, and bending moment of the composite plates. It is found that the delamination leads to a substantial reduction in the thermal load-carrying capacity. Furthermore, depending on the boundary conditions and stacking sequence, the response of the perfect composite plates could be either of the bifurcation type or of the unique stable path.