This paper studies the free vibration of the functionally graded doubly curved nanoshells using nonlocal first-order shear deformation theory with variable nonlocal parameters. The novelty of the current work is that the nonlocal parameters vary smoothly through the thickness of the nanoshells which is never investigated in the past. Four types of the doubly curved nanoshells named flat plates, spherical shells, hyperbolic parabolic shells, and cylindrical shells are considered. The first-order shear deformation theory, the nonlocal elasticity theory, and Hamilton’s principle are used to establish the governing equations of motion of the functionally graded doubly curved nanoshells. The frequencies of the simply supported functionally graded doubly curved nanoshells are carried out via Navier’s solution technique. The numerical results obtained by the proposed formulations are compared with other published results in several special cases to demonstrate the accuracy and efficiency of the developed model. Furthermore, the effects of some parameters such as the nonlocal parameters, the power-law index, the thickness-to-sides ratio, the radius ratio on the free vibration response of the functionally graded doubly curved nanoshells are investigated in detail.

Similar to many new engineering ideas that are actually interdisciplinary subjects, magneto-electro-elastic (MEE) structures also need accurate ways of describing their structural behaviors. Based on nonlocal elasticity theory, the present article investigates the vibroacoustic behavior of a hollow multilayer cylindrical nanoshell where the core layer is made of isotropic functionally graded material (FGM) and other layers are made of MEE materials. The proposed system also is subjected to combined loads which contain a plane sound wave, the initial external electric and magnetic loads, and external mean airflow. The displacement field of structure is described using the third-order shear deformation assumption (TSDA). The derivation of vibroacoustic equations in the form of coupled relations is realized by implementing Hamilton's principle. The material properties of FGM core layer are supposed to vary along the in-plane and thickness directions based on the power-law model. The final objective is to analyze the sound transmission loss (STL) characteristics of the structure and inspect the accuracy of the developed method against existing data followed by comparing the results in terms of geometric and acoustic parameters. The obtained results and the described method can be used advantageously to better optimize such structures by choosing appropriate initial electric and magnetic potentials, flow Mach number, nonlocal parameter, material gradient index, incident angles.

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Jenny
Journal Co-ordinator
Journal of Nano Research & Applications