Nonlinear buckling and postbuckling analysis of FG-GRMMC cylindrical panels with oblique and orthogonal stiffeners in thermal environment

Advanced composite materials, with their superior strength-to-weight ratio, durability, and thermal resistance, are increasingly applied in civil engineering for withstanding harsh mechanical and environmental loads. This paper presents a nonlinear stability analysis of cylindrical panels made from a new type of composite material, namely, functionally graded graphene-reinforced metal matrix composite (FG-GRMMC). The panels are stiffened by oblique or orthogonal FG-GRMMC stiffeners. The fundamental formulation is developed using higher-order shear deformation theory (HSDT), incorporating von Kármán geometric nonlinearity. The effects of stiffeners are modeled using an enhanced smeared stiffener technique for both mechanical and thermal effects through coordinate transformation. The governing equations are derived and solved using the Ritz energy method. Different graphene distribution patterns and stiffener orientations are systematically investigated to evaluate their effects on critical buckling and postbuckling responses. The results highlight the significant improvements in structural stability achieved through the use of oblique stiffeners and optimized material, particularly under thermal loading conditions