## 1 Introduction  
Today, stiffened cylindrical shells are widely used in a variety of engineering systems, including aircraft, spacecraft, submarine, naval, automotive, and civil applications. In particular, attention has been devoted to study the stability of stiffened composite shells and materials that are usually subjected to sever thermal environments and loadings. Many thermal buckling studies of laminated composite shells can be found in the literature, which aim at determining the critical mechanical loading under uniform or non-uniform thermal conditions (see e.g., [1; 2; 3; 4; 5; 6; 7] among others). Thus, different analytical and/or numerical formulations have been considered to approach thermal buckling problems of plate and shell structures. A first-order shear deformation theory (FSDT), for example, was applied by Tauchert [8] and Avci et al. [9] to study the buckling behavior of cross-ply laminated hybrid composite laminates under a uniform thermal loading. Meanwhile, Lee [10] studied the thermal buckling of composite plates by using a layer-wise theory, whereas Matsunaga [11] solved the same problem by using a global higher order deformation theory. Baruta et al. [12] applied a nonlinear finite element analysis to study the response of moderately thick laminated panels in large deformations under a non-uniform temperature field. A differential quadrature method was adopted by Ghomshei and Mahmoudi [13] to analyze the thermal buckling behavior of symmetric cross-ply laminated rectangular thin plates subjected to a uniform and/or non-uniform thermal loading. More in detail, a parametric study was performed by the authors to investigate the effect of some geometrical and mechanical parameters--including the stiffness ratios, cross-ply ratios, and aspect ratios--on the critical thermal temperature and buckling behavior of thin plates. In the last decades, many optimization problems have also gained much attention for design purposes in order to define the optimal buckling temperature of a composite structure (see [14; 15; 16; 17; 18; 19] among others). However, there is a general lack of information about the thermal buckling behavior of composite plates and shells in presence of CNT reinforcements and/or structural stiffeners. Some preliminary works [20; 21; 22; 23; 24], for example, examined the buckling behavior of composite shells reinforced with stiffeners without considering any possible effect related to a thermal loading condition. Moreover, Nejati et al. [25] studied the mechanical buckling behavior of FG cantilever beams while considering the agglomeration effect of CNTs within the structures. Mohammadzadeh et al. [26] analyzed the mechanical buckling of two-dimensional FG cylindrical shells subjected to an axial and pressure loading, according to a classical theory. The effect of temperature distributions on the mechanical properties of Functionally Graded Material (FGM) composites and non-homogeneous materials was also studied in [27; 28; 29; 30; 31; 32] while focusing on the presence of fibers or CNTs as reinforcement. Such materials and structures, however, have shown complex thermal buckling behavior due to the large displacements and rotations they can experience in the presence of a generally distributed temperature. To this end, in the present work, we provide a parametric investigation on the stability of FG wavy CNT stiffened cylindrical shells under a uniform thermal loading, where the materials feature some temperature-dependent properties. More specifically, we discuss about the main effects of nanomaterials and stiffeners on the critical thermal buckling load for CNTRC cylindrical shells with temperature-dependent properties.