Mechanical Formulation for Pre-twisted Micro/Nano Beams Based on the Strain Gradient Theory

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Javadi Sigaroudi, Mohammad Javad | 2014

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 45976 (08)
University: Sharif University of Technology
Department: Mechanical Engineering
Advisor(s): Asghari, Mohsen
Abstract:
One of the extensively used, yet complex, structures in the industry is pre-twisted Micro/Nano beams. Studying their mechanical behavior helps to have a broader view of them. In this present study, explores and analyzes the behavior of a pre-twisted Micro/Nano beam with a quadrangular/rectangular cross-section using the strain gradient theory and modified couple stress theory. Using the calculus of variations and the Hamiltonian principle the elastodynamics governing partial differential equations of transverse deflection of the pre-twisted Micro/Nano beam with hinged-hinged boundary conditions are derived. Then the mechanical behavior of the pre-twisted Micro/Nano beam in static mode and free vibrations are investigated and the effects of pre-twisted angular are demonstrated in natural frequencies and transverse deflection under static load. Finally, the results obtained are compared with those of the classical solving model and the modified couple stress theory
Keywords:
Couple Stress ; Size Effect ; Strain Gradient Theory ; Modified Couple Stress Theory ; Pre-Twisted Micro/Nano Scale Beams ; Lam's Theory

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