Applied Mathematics and Mechanics (English Edition) ›› 2021, Vol. 42 ›› Issue (3): 425-440.doi: https://doi.org/10.1007/s10483-021-2708-9

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Torsional static and vibration analysis of functionally graded nanotube with bi-Helmholtz kernel based stress-driven nonlocal integral model

Peiliang BIAN, Hai QING   

  1. State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
  • 收稿日期:2020-10-23 修回日期:2020-12-15 发布日期:2021-02-23
  • 通讯作者: Hai QING E-mail:qinghai@nuaa.edu.cn
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (No. 11672131) and the Priority Academic Program Development of Jiangsu Higher Education Institutions

Torsional static and vibration analysis of functionally graded nanotube with bi-Helmholtz kernel based stress-driven nonlocal integral model

Peiliang BIAN, Hai QING   

  1. State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
  • Received:2020-10-23 Revised:2020-12-15 Published:2021-02-23
  • Contact: Hai QING E-mail:qinghai@nuaa.edu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (No. 11672131) and the Priority Academic Program Development of Jiangsu Higher Education Institutions

摘要: A torsional static and free vibration analysis of the functionally graded nanotube (FGNT) composed of two materials varying continuously according to the power-law along the radial direction is performed using the bi-Helmholtz kernel based stress-driven nonlocal integral model. The differential governing equation and boundary conditions are deduced on the basis of Hamilton’s principle, and the constitutive relationship is expressed as an integral equation with the bi-Helmholtz kernel. Several nominal variables are introduced to simplify the differential governing equation, integral constitutive equation, and boundary conditions. Rather than transforming the constitutive equation from integral to differential forms, the Laplace transformation is used directly to solve the integro-differential equations. The explicit expression for nominal torsional rotation and torque contains four unknown constants, which can be determined with the help of two boundary conditions and two extra constraints from the integral constitutive relation. A few benchmarked examples are solved to illustrate the nonlocal influence on the static torsion of a clamped-clamped (CC) FGNT under torsional constraints and a clamped-free (CF) FGNT under concentrated and uniformly distributed torques as well as the torsional free vibration of an FGNT under different boundary conditions.

关键词: integro-differential equation, bi-Helmholtz kernel, stress-driven nonlocal integral model, Laplace transform technique, free vibration

Abstract: A torsional static and free vibration analysis of the functionally graded nanotube (FGNT) composed of two materials varying continuously according to the power-law along the radial direction is performed using the bi-Helmholtz kernel based stress-driven nonlocal integral model. The differential governing equation and boundary conditions are deduced on the basis of Hamilton’s principle, and the constitutive relationship is expressed as an integral equation with the bi-Helmholtz kernel. Several nominal variables are introduced to simplify the differential governing equation, integral constitutive equation, and boundary conditions. Rather than transforming the constitutive equation from integral to differential forms, the Laplace transformation is used directly to solve the integro-differential equations. The explicit expression for nominal torsional rotation and torque contains four unknown constants, which can be determined with the help of two boundary conditions and two extra constraints from the integral constitutive relation. A few benchmarked examples are solved to illustrate the nonlocal influence on the static torsion of a clamped-clamped (CC) FGNT under torsional constraints and a clamped-free (CF) FGNT under concentrated and uniformly distributed torques as well as the torsional free vibration of an FGNT under different boundary conditions.

Key words: integro-differential equation, bi-Helmholtz kernel, stress-driven nonlocal integral model, Laplace transform technique, free vibration

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