Advances in Nano Research

Volume 16, Number 5, 2024, pages 473-487

DOI: 10.12989/anr.2024.16.5.473

Assessment of nonlocal nonlinear free vibration of bi-directional functionally-graded Timoshenko nanobeams

Elnaz Zare , Daria K. Voronkova , Omid Faraji , Hamidreza Aghajanirefah , Hamid Malek Nia , Mohammad Gholami , Mojtaba Gorji Azandariani

Abstract

The current study employs the nonlocal Timoshenko beam (NTB) theory and von-Kármán's geometric nonlinearity to develop a non-classic beam model for evaluating the nonlinear free vibration of bi-directional functionally-graded (BFG) nanobeams. In order to avoid the stretching-bending coupling in the equations of motion, the problem is formulated based on the physical middle surface. The governing equations of motion and the relevant boundary conditions have been determined using Hamilton's principle, followed by discretization using the differential quadrature method (DQM). To determine the frequencies of nonlinear vibrations in the BFG nanobeams, a direct iterative algorithm is used for solving the discretized underlying equations. The model verification is conducted by making a comparison between the obtained results and benchmark results reported in prior studies. In the present work, the effects of amplitude ratio, nanobeam length, material distribution, nonlocality, and boundary conditions are examined on the nonlinear frequency of BFG nanobeams through a parametric study. As a main result, it is observed that the nonlinear vibration frequencies are greater than the linear vibration frequencies for the same amplitude of the nonlinear oscillator. The study finds that the difference between the dimensionless linear frequency and the nonlinear frequency is smaller for CC nanobeams compared to SS nanobeams, particularly within the

Key Words

bi-directional functionally-graded; differential quadrature method; Eringen's nonlocal theory; nanobeams; nonlinear vibration

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