Abstract
Smart nanostructures have many practical application in nano-electro-mechanical systems (NEMS) as sensor and actuator. Present research deals with the vibration and damping of advanced sandwich smart nanoshells. This nanostructure comprised of porous nanoshell coated by nanocomposite piezoelectric layers as sensor and actuator. The nanocompisite layers are reinforced by graphene platelets (GPLs) with various distributions based on Halpin-Tsai model. In order to presume this sandwich structure much more realistic, Kelvin model will be utilized and it is surrounded by visco-Pasternak foundation. Further, non-local surface piezoelasticity theory is employed for considering the small scale and surface effects. On the basis of zigzag shear-deformation theory and Hamilton principle, the motion equations are derived. Differential cubature method (DCM) is used as numerical method for calculating natural frequency and damping ratio. In order to validate the results, this paper is compared by another simplified cases and ABAQUS commercial software. Finally, the influences of porosity and its distribution, volume percent and distribution of GPLs, surface stresses, small scale parameter, and external voltage are shown on natural frequency and damping. The results show that the damping ratio and frequency of system considering surface effect with symmetric porosity distribution decrease and increases about 17% and 25% compared to the without surface effect case and asymmetric porosity respectively. In addition, the nanostructure in critically damped state can be turned into underdamped state by applying negative voltage. Furthermore, the dispersion of GPLs near the bottom and top surface of nanocomposite layers is the best choice due to high stiffness and frequency.
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