Improved refined plate theory accounting for effect of thickness stretching in functionally graded plates

In this paper, the refined pate theory is improved to account for the effect of thickness stretching in functionally graded plates. The refined plate theory has fewer number of unknowns and equations of motion than the first-order shear deformation theory, but accounts for the transverse shear deformation effects without requiring shear correction factors. The displacement field of the refined plate theory is modified by assuming a parabolic variation of the transverse displacement through the thickness, and consequently, the thickness stretching effect is taken into consideration. Closed-form solutions of simply supported rectangular plates are presented, and the obtained results are compared with 3D solutions and those predicted by higher-order shear deformation theories. Verification studies show that the proposed theory is not only more accurate than the refined plate theory, but also comparable with the higher-order shear deformation theories which contain more number of unknowns.