Applied Mathematics and Mechanics (English Edition) ›› 2016, Vol. 37 ›› Issue (7): 861-878.doi: https://doi.org/10.1007/s10483-016-2094-9

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Free vibration analysis of functionally graded material beams based on Levinson beam theory

Xuan WANG1, Shirong LI1,2   

  1. 1. School of Hydraulic, Energy and Power Engineering, Yangzhou University, Yangzhou 225127, Jiangsu Province, China;
    2. School of Civil Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu Province, China
  • 收稿日期:2015-10-14 修回日期:2016-03-02 出版日期:2016-07-01 发布日期:2016-07-01
  • 通讯作者: Shirong LI E-mail:srli@yzu.edu.cn
  • 基金资助:

    Project supported by the National Natural Science Foundation of China (No. 11272278)

Free vibration analysis of functionally graded material beams based on Levinson beam theory

Xuan WANG1, Shirong LI1,2   

  1. 1. School of Hydraulic, Energy and Power Engineering, Yangzhou University, Yangzhou 225127, Jiangsu Province, China;
    2. School of Civil Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu Province, China
  • Received:2015-10-14 Revised:2016-03-02 Online:2016-07-01 Published:2016-07-01
  • Contact: Shirong LI E-mail:srli@yzu.edu.cn
  • Supported by:

    Project supported by the National Natural Science Foundation of China (No. 11272278)

摘要:

Free vibration response of functionally graded material (FGM) beams is studied based on the Levinson beam theory (LBT). Equations of motion of an FGM beam are derived by directly integrating the stress-form equations of elasticity along the beam depth with the inertial resultant forces related to the included coupling and higherorder shear strain. Assuming harmonic response, governing equations of the free vibration of the FGM beam are reduced to a standard system of second-order ordinary differential equations associated with boundary conditions in terms of shape functions related to axial and transverse displacements and the rotational angle. By a shooting method to solve the two-point boundary value problem of the three coupled ordinary differential equations, free vibration response of thick FGM beams is obtained numerically. Particularly, for a beam with simply supported edges, the natural frequency of an FGM Levinson beam is analytically derived in terms of the natural frequency of a corresponding homogenous Euler-Bernoulli beam. As the material properties are assumed to vary through the depth according to the power-law functions, the numerical results of frequencies are presented to examine the effects of the material gradient parameter, the length-to-depth ratio, and the boundary conditions on the vibration response.

关键词: Levinson beam theory (LBT), free vibration, natural frequency, functionally graded material (FGM)beam, shooting method

Abstract:

Free vibration response of functionally graded material (FGM) beams is studied based on the Levinson beam theory (LBT). Equations of motion of an FGM beam are derived by directly integrating the stress-form equations of elasticity along the beam depth with the inertial resultant forces related to the included coupling and higherorder shear strain. Assuming harmonic response, governing equations of the free vibration of the FGM beam are reduced to a standard system of second-order ordinary differential equations associated with boundary conditions in terms of shape functions related to axial and transverse displacements and the rotational angle. By a shooting method to solve the two-point boundary value problem of the three coupled ordinary differential equations, free vibration response of thick FGM beams is obtained numerically. Particularly, for a beam with simply supported edges, the natural frequency of an FGM Levinson beam is analytically derived in terms of the natural frequency of a corresponding homogenous Euler-Bernoulli beam. As the material properties are assumed to vary through the depth according to the power-law functions, the numerical results of frequencies are presented to examine the effects of the material gradient parameter, the length-to-depth ratio, and the boundary conditions on the vibration response.

Key words: Levinson beam theory (LBT), free vibration, functionally graded material (FGM)beam, shooting method, natural frequency

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