Finite Element Modeling and Free Vibration Analysis of Functionally Graded Nanocomposite Beams Reinforced by Randomly Oriented Carbon Nanotubes

This article deals with the finite element modeling and free vibration analysis of functionally graded nanocomposite beams reinforced by randomly oriented straight single-walled carbon nanotubes (SWCNTs). Nanostructural materials can be used to alter mechanical, thermal and electrical properties of polymer-based composite materials, because of their superior properties and perfect atom arrangement. Timoshenko beam theory is used to evaluate dynamic characteristics of the beam. The Eshelby–Mori–Tanaka approach based on an equivalent fiber is used to investigate the material properties of the beam. The equations of motion are derived by using Hamilton’s principle. The finite element method is employed to discretize the model and obtain a numerical approximation of the motion equation. Different SWCNTs distributions in the thickness direction are introduced to improve fundamental natural frequency and dynamic behavior of uniform functionally graded nanocomposite beam. Results are presented in tabular and graphical forms to show the effects of various material distributions, carbon nanotube orientations, shear deformation, slenderness ratios and boundary conditions on the dynamic behavior of the beam. The first five normalized mode shapes for functionally graded carbon nanotube reinforced composite (FG-CNTRC) beams with different boundary conditions and different carbon nanotubes (CNTs) orientation are presented. The results show that the above mentioned effects play very important role on the dynamic behavior of the beam.