Bending and vibration of functionally graded sinusoidal microbeams based on the strain gradient elasticity theory

In this paper, a novel size-dependent beam model made of functionally graded materials (FGMs) is developed based on the strain gradient elasticity theory and sinusoidal shear deformation theory. The material properties of the functionally graded (FG) microbeams are assumed to vary in the thickness direction and are estimated through the Mori-Tanaka homogenization technique. Governing equations and boundary conditions are derived simultaneously by using Hamilton's principle. The new model contains three material length scale parameters and can consequently capture the size effect. In addition, the newly developed model degenerates to the modified couple stress sinusoidal beam model or the classical sinusoidal beam model by setting two or all material length scale parameters to zero. The Navier-type solution is developed for simply-supported boundary conditions. Numerical results are presented to investigate the influences the material length scale parameter, different material compositions, and shear deformation on the bending and free vibration behavior of FG microbeams. Some of the present results are compared with the previously published results to establish the validity of the present formulation. It is established that the present FG microbeams exhibit significant size-dependence when the thickness of the microbeam approaches to the material length scale parameter. (C) 2013 Elsevier Ltd. All rights reserved.