An accurate shear deformation theory for vibration and buckling of FGM sandwich plates in hygrothermal environment

A new accurate four-variable shear deformation plate theory is introduced in this paper to illustrate the hygrothermal vibration and buckling of FGM sandwich plates resting on Winkler-Pasternak elastic foundations. Based on the suggested theory, the equations of motion are derived from Hamilton׳s principle containing the hygrothermal effects. This theory involves only four unknown functions and accounts for quasi-parabolic distribution of transverse shear stress. In addition, the transverse shear stresses are vanished at the top and bottom surfaces of the sandwich plate. A power law distribution is used to govern the gradation of material properties through the plate thickness. Various types of FGM sandwich plates are considered. To check the validity of the theory and formulations, the obtained results are compared with the previous results. Comparison studies reveal that the results of the proposed theory are more accurate than those of other shear deformation plate theories. Parametric study is performed to show the influences of moisture condition, temperature rise, elastic foundation coefficients and power law index on the buckling and natural frequency of FGM sandwich plates.