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Steel and Composite Structures
  Volume 42, Number 5, March10 2022 , pages 699-710
DOI: https://doi.org/10.12989/scs.2022.42.5.699
 


Axial frequency analysis of axially functionally graded Love-Bishop nanorods using surface elasticity theory
Reza Nazemnezhad and Hassan Shokrollahi

 
Abstract
    This work presents a comprehensive study on the surface energy effect on the axial frequency analyses of AFGM nanorods in cylindrical coordinates. The AFGM nanorods are considered to be thin, relatively thick, and thick. In thin nanorods, effects of the inertia of lateral motions and the shear stiffness are ignored; in relatively thick nanorods, only the first one is considered; and in thick nanorods, both of them are considered in the kinetic energy and the strain energy of the nanorod, respectively. The surface elasticity theory which includes three surface parameters called surface density, surface stress, and surface Lame constants, is implemented to consider the size effect. The power-law form is considered for variation of the material properties through the axial direction. Hamilton's principle is used to derive the governing equations and boundary conditions. Due to considering the surface stress, the governing equation and boundary condition become inhomogeneous. After homogenization of them using an appropriate change of variable, axial natural frequencies are calculated implementing harmonic differential quadrature (HDQ) method. Comprehensive results including effects of geometric parameters and various material properties are presented for a wide range of boundary condition types. It is believed that this study is a comprehensive one that can help posterities for design and manufacturing of nano-electro-mechanical systems.
 
Key Words
    free axial vibration; functionally graded materials; harmonic differential quadrature method; nanorod; surface energy
 
Address
Reza Nazemnezhad:School of Engineering, Damghan University, Damghan, Iran

Hassan Shokrollahi:Department of Mechanical Engineering, Faculty of Engineering, Kharazmi University, Tehran, Iran
 

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