Applied Mathematics and Mechanics (English Edition) ›› 2017, Vol. 38 ›› Issue (2): 217-230.doi: https://doi.org/10.1007/s10483-017-2167-9

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Free torsional vibration of cracked nanobeams incorporating surface energy effects

R. NAZEMNEZHAD1, P. FAHIMI2,3   

  1. 1. School of Engineering, Damghan University, Damghan 36716-41167, Iran;
    2. School of Mechanical Engineering, Iran University of Science and Technology, Tehran 16846-13114, Iran;
    3. School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran 14399-57131, Iran
  • Received:2016-03-06 Revised:2016-08-20 Online:2017-02-01 Published:2017-02-01
  • Contact: R.NAZEMNEZHAD E-mail:rnazemnezhad@du.ac.ir

Abstract:

This paper investigates surface energy effects, including the surface shear modulus, the surface stress, and the surface density, on the free torsional vibration of nanobeams with a circumferential crack and various boundary conditions. To formulate the problem, the surface elasticity theory is used. The cracked nanobeam is modeled by dividing it into two parts connected by a torsional linear spring in which its stiffness is related to the crack severity. Governing equations and corresponding boundary conditions are derived with the aid of Hamilton's principle. Then, natural frequencies are obtained analytically, and the influence of the crack severity and position, the surface energy, the boundary conditions, the mode number, and the dimensions of nanobeam on the free torsional vibration of nanobeams is studied in detail. Results of the present study reveal that the surface energy has completely different effects on the free torsional vibration of cracked nanobeams compared with its effects on the free transverse vibration of cracked nanobeams.

Key words: cracked nanobeam, surface energy, torsional vibration

2010 MSC Number: 

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