Thermal postbuckling analysis of temperature dependent delaminated composite plates

• Thermal instability of delaminated composite plates has been examined.
• Delamination decreases the critical buckling temperature of composite plates.
• Load carrying capacity of laminates decreases by increasing delamination size.
• A methodology is developed for both local/global buckling analysis of composites.

This paper deals with the nonlinear thermal stability of composite plate with embedded and through-the-width delaminations under uniform temperature rise. The formulation is established within the framework of the higher order shear deformation theory by taking into account the von Karman geometrical nonlinearity. The thermomechanical properties of the laminates are assumed to be temperature-dependent. The nonlinear equilibrium equations derived by the minimum total potential energy principle, are solved using the Rayleigh–Ritz method along with the Newton–Raphson iterative procedure. For modeling the embedded and through-the-width delaminations, the plate is divided into a number of smaller regions. 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. Numerical results are presented to provide an insight into effects of delamination type, size of delamination and boundary condition on the critical buckling temperature difference, buckling mode and postbuckling behavior of the composite plate. It is found that presence of delamination leads to substantial reduction in the load carrying capacity of the composite plate. Furthermore, the results reveal that the buckling mode could be changed depending on the delamination area.