Free vibration analysis of a bidirectional functionally graded carbon nanotube reinforced composite beam

Based on the Timoshenko beam theory, the vibration properties of a bidirectional functionally graded carbon nanotube reinforced composite beam are investigated. The governing equation of free vibration for the composite beam is derived, which considers the main influential factors, such as the gradient index and the distribution, aspect ratio, and volume ratio of carbon nanotubes. The differential quadrature method is used to solve the governing equation. The natural frequency of the composite beam is obtained. It is found that the natural frequency and vibration mode shapes of the beam are dependent upon the gradient index, nanotube distribution, and volume ratio of nanotubes. However, it should be pointed out that the nanotube distribution in the height direction and the volume ratio of nanotubes have very limited effects on the mode shapes of the composite beam.