Nonlinear vibration of nanotube-reinforced composite cylindrical shells in thermal environments

This paper investigates the large amplitude vibration behavior of nanocomposite cylindrical shells reinforced by single-walled carbon nanotubes (SWCNTs) in thermal environments. The SWCNTs are assumed to be aligned and straight with a uniform layout. Two kinds of carbon nanotube-reinforced composite (CNTRC) shells, namely, uniformly distributed (UD) and functionally graded (FG) reinforcements, are considered. The material properties of FG-CNTRC shells are assumed to be graded in the thickness direction, and are estimated through a micromechanical model. The motion equations are based on a higher-order shear deformation theory with a von Kármán-type of kinematic nonlinearity. The thermal effects are also included and the material properties of CNTRCs are assumed to be temperature-dependent. The equations of motion are solved by an improved perturbation technique to determine the nonlinear frequencies of the CNTRC shells. Numerical results demonstrate that in most cases the natural frequencies of the CNTRC shells are reduced but the nonlinear to linear frequency ratios of the CNTRC shells are increased as the temperature rises. It is found that the natural frequencies are increased by increasing the CNT volume fraction, whereas the CNTRC shells with intermediate CNT volume fraction do not have intermediate nonlinear to linear frequency ratios.