On the frequency characteristics of rotating combined conical-conical shells made of FG-CNTRC composite materials under thermal environments

Abstract

The current paper is focused on the frequency features of spinning coupled functionally graded carbon nanotube reinforced (FG-CNTRC) cone-cone shells undergoing high temperatures. The physic of the structures is based on two conical shell segments with different semi-vertex angles that are merges via the ideal bonding at the junctures. Simultaneous consideration of environmental thermal effects and rotation about the structure’s axis in dealing with conditions near and also far from critical speeds and buckling temperatures could add the novelty of the available paper. The frequency inspections include the study of free vibration behavior, frequency bifurcation of traveling waves and also identifying instability regions with regard to critical thermal buckling and critical speed phenomena. A two-step procedure based on first order shear deformation theory (FSDT) and von Kármán assumptions is employed to access the system’s formulation. Firstly, the initial thermal stress resultants are captured upon static step and then utilized through the dynamic step. Afterward, generalized differential quadrature (GDQ) method is implemented on the set of governing equations. After verifying the precision of results, some parametric studies are provided to investigate the effects of temperature and rotary speed elevations, radius and position of conjunction, CNT volume fraction and distribution schemes on the dynamic attributes of the spinning structure.