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In this article, free vibration and resonance of finite length functionally graded (FG) nanocomposite cylinders are investigated by a mesh-free method. These cylinders are reinforced by wavy single-walled carbon nanotubes (SWCNTs) and subjected to a periodic internal pressure. Three linear types of FG distributions and a uniform distribution of wavy carbon nanotubes (CNTs) are considered along the radial direction of axisymmetric cylinder. The mechanical properties are simulated using a micromechanical model in volume fraction form. In the mesh-free analysis, moving least squares shape functions are used for approximation of displacement field in the weak form of motion equation and the transformation method is used for imposition of essential boundary conditions. Effects of geometric dimensions, boundary conditions and also, waviness index, aspect ratio, volume fraction, and distribution pattern of CNTs are investigated on the natural frequencies and resonance behaviors of FG carbon nanotube reinforced composite (CNTRC) cylinders. It is observed that CNT waviness has a significant effect on the vibrational behavior of the CNTRC cylinders.

AbstractReinforcing polymers with nanofillers is an advanced approach to improve and manage the thermal behaviors of polymeric nanocomposite materials. Among the proposed nanofillers, graphene and carbon nanotube (CNT) with superior thermal conductivity are two advanced nanofillers, which have extensively been utilized to enhance the heat transfer responses of host polymeric materials. In this work, the impacts of randomly oriented graphene and CNT to steady state and transient heat transfer behaviors of functionally graded (FG) nanocomposite cylinders have been investigated using an axisymmetric model. Nanocomposite cylinders have been assumed to be under heat fluxes, heat convections or temperatures as different types of thermal boundary conditions. The thermal properties of the resulted nanocomposite materials are estimated by micromechanical model. Moreover, the governing thermal equations of axisymmetric cylinders have been analyzed using a highly consistent and reliable developed mesh-free method. This numerical method predicts temperature fields via MLS shape functions and imposes essential boundary conditions with transformation approach. The effects of nanofiller content and distribution as well as thermal boundary conditions on the heat transfer responses of nanocomposite cylinders are studied. The results indicated that the use of nanofiller resulted in shorter stationary times and higher temperature gradients in FG nanocomposite cylinders. Moreover, the use of graphene in nanocomposites had stronger impact on thermal response than CNT.

In the present work, a new axisymmetric weak form meshless method is presented for analysis of free vibration of functionally graded material (FGM) cylinders. This method is based on weak form of equilibrium equation and moving least squares (MLS) approximation. Essential boundary conditions are imposed by transformation method. In this method, shape functions that do not satisfy the Kronecker delta condition are corrected, then essential boundary conditions are imposed easily as in the finite element method (FEM). In the present work, the material is assumed to be functionally graded in the radial direction. Variations in the material properties such as Young’s modulus and Poisson’s ratio may be arbitrary functions of the radial coordinate. The FGM cylinder material varies continuously from silicon carbide (SiC) on the inner surface to stainless steel (SUS304) on the outer surface. Free vibration analysis of FGM cylinders with any arbitrary combination of boundary conditions is possible by the proposed model. Natural frequencies obtained from the presented model are in good agreement with results of finite element simulation. Effects of various types of boundary conditions, geometrical parameters, and mechanical properties on the natural frequencies are studied.

In this paper, static analysis of nanocomposite cylinders reinforced by single-walled carbon nanotubes subjected to internal and external pressure was carried out by a mesh-free method. In the mesh-free analysis, moving least squares shape functions are used for approximation of displacement field in the weak form of equilibrium equation. Four types of distributions of the aligned carbon nanotubes are considered: uniform and three kinds of functionally graded distributions along the radial direction of cylinder. Material properties are estimated by a micro-mechanical model. In this simulation, an axisymmetric model is used. Detailed parametric studies have been carried out to investigate the influences of the kind of distribution and volume fractions of carbon nanotubes and cylinder thickness on displacement and stress fields for carbon nanotube-reinforced composite cylinders. Results obtained for this analysis were compared with analytical solutions and good agreement was seen between them.