Due to the rapid development of process manufacturing, composite materials with graphene-reinforcement have obtained commercially notices in promoted engineering applications. For this regard, vibrational characteristics of a cylindrical nanoshell reinforced by graphene nanoplatelets (GPL) and coupled with piezoelectric actuator (PIAC) is investigated. Also, the nanostructure is embedded in a viscoelastic medium. The material properties of piece-wise graphene-reinforced composite (GPLRC) are assumed to be graded in the thickness direction of a cylindrical nanoshell and estimated through a nanomechanical model. For the first time in the current study is considering the effects of piezoelectric layer, viscoelastic foundation, GPLRC, and size-effects on the frequency responses of the GPLRC cylindrical nanoshell coupled with PIAC and by assuming perfect bonding between the core (GPLRC cylindrical shell) and the piezoelectric layer. The governing equations and boundary conditions have been developed using minimum potential energy and solved with the aid of the generalized differential quadrature method. In addition, because of piezoelectric layer, Maxwell's equation is derived. The results show that viscoelastic foundation, piezoelectric layer, GPL distribution pattern, length scale parameter and GPL weight function have important role in the frequency characteristics of the GPLRC cylindrical nanoshell coupled with PIAC and surrounded by viscoelastic foundation. The results of the current study are useful suggestions for design of materials science, micro-electro-mechanical systems, and nanoelectromechanical systems such as nanoactuators and nanosensors. Communicated by Francesco Tornabene.

This article investigates the influences of nonuniform imperfection on the dynamic amplitude and resonance frequency of the nanoshell reinforced with graphene nanoplatelet (GNP). The novelty of the current study is to consider the effects of porosity, thermal loading and graphene platelet reinforced composites on the dynamic behavior of the nanostructure. Three-length scale parameters (l₀=5 h, l₁=3 h, l₂=5 h) in the modified strain gradient theory (MSGT) show a better agreement with MD simulation in comparison with other theories. Finally, the effects of different factors on the dynamic amplitude and resonance frequency of the porous nanostructure are examined in detail.

This is the first research on the pre-thermal buckling and vibration analysis of imperfect graphene nanoplatelets reinforced composite (GPLRC) doubly curved open cylindrical micropanel in the framework of numerical based two dimensional-generalized differential quadrature method (2D-GDQM). Additionally, the small-scale effects are analyzed based on nonlocal strain gradient theory (NSGT). The stresses and strains are obtained using the high order shear deformable theory (HOSDT). Rule of mixture is employed to obtain varying mass density, thermal expansion, and Poisson’s ratio, while module of elasticity is computed by modified Halpin–Tsai model. In addition, nonlinear temperature changes along the GPLRC micro panel’s thickness direction. Governing equations and boundary conditions of the GPLRC doubly curved open cylindrical micropanel are obtained by implementing Hamilton’s principle. Besides, for the validation of the results, the results of current model are compared to the results acquired from analytical method. The results show that GPL weight function ( $g_{\mathit{GPL}}$), imperfection, the ratio of shell curvatures (R₁/R₂), NSG parameters, and geometric parameters have significant influence on the frequency and pre-thermal buckling characteristics of the GPLRC doubly curved open cylindrical micropanel.

Smart control and dynamic investigation of a graphene nanoplatelets composite (GPLRC) cylindrical microshell surrounded by a piezoelectric layer as actuator and sensor based on a numerical solution method called generalized differential quadrature method are presented for the first time. The current structure is under an external load. The strains and stresses can be determined through via the first-order shear deformable theory. For accessing to various mass densities, thermal expansion as well as Poisson ratio, the rule of mixture is applied, although, a modified Halpin–Tsai theory is used for obtaining the module of elasticity. The external voltage is applied to the sensor layer, while a proportional-derivative (PD) controller has been utilized for controlling output of sensor. GPLRC’s boundary conditions are derived through governing equations of the cylindrical microshell using energy method known as Hamilton’s principle. The outcomes show that the PD controller, viscoelastic foundation, slenderness factor (L/R), external voltage, and GPL’s weight fraction have a considerable impact on the amplitude, and vibration behavior of a smart GPLRC cylindrical microshell. As an applicable result in related industries, the parameter and consideration of the PD controller have a positive effect on the static and dynamic behaviors of the microstructure subjected to external load.

Investigation of repaired crack in pressure vessels plays a critical role in the maintenance of cylindrical vessels which are under static loads. Pressurized vessels are critical elements in many industries that may be subjected to degradation and cracking due to working conditions. There are several methods to repair such reservoirs, including welding of damaged points, but this is not possible in some conditions, such as the presence of inflammable materials inside the reservoir. One of the most reliable ways to repair these types of vessels is using composite materials. In this research, crack created in the reservoir is repaired using carbon / epoxy composites. Results of this study confirm the association between the strength of vessels walls and thickness of composite materials. In this paper, the effect of different parameters such as thickness and radius of the reservoir, and composite thickness are investigated. The results show that increasing the thickness of the composite is effective, so by doubling the thickness of composite, stress intensity factor decreases by 13%. Moreover, the use of composites in thin wall tanks is much more effective than the case of a thick reservoir wall.

In this study, the dynamic stability and energy absorption of a novel type of sandwich panels with an extensive application in light vehicles are investigated. The curved panels are laminated multi-scale hybrid nanocomposites reinforced with carbon nanotubes. The whole panel is on a non-polynomial viscoelastic substrate to control the stability of the panel following vibrations. The 3D elasticity model is utilized for analyzing dynamic behavior and energy absorption. Moreover, a non-polynomial viscoelastic model is employed to take the effect of the viscoelastic substrate into account. The equivalent bulk properties of the nanocomposite are obtained using micromechanics and Halpin–Tsai relations. The nano-reinforcements are considered to have even distribution and random orientations in the epoxy matrix. The effects of material and loading conditions including viscoelastic parameters, compressibility, fiber’s volume and weight fractions, damping factor, and initial axially stress on the dynamic stability of the curved panels are evaluated. The most important outcome of this paper is that the change in ${\sigma }_r^{-o}$ parameters has a significant effect on dependency of energy absorption on radial stress. In application, the results suggest decreasing compressibility leads to increasing energy absorption of the shell structure.