Free vibration of FGM sandwich doubly-curved shallow shell based on a new shear deformation theory with stretching effects

Free vibration of the functionally graded material (FGM) sandwich doubly-curved shallow shells under simply supported conditions is presented. Three common types of the shell, namely, the shell with homogeneous hardcore and FGM facesheet (type A), the shell with homogeneous softcore and FGM facesheet (type B) and the shell with FGM core and homogeneous facesheet (type C), are discussed. The dynamics model is derived according to a new shear deformation theory with stretching effects. The dimensionless natural frequency is obtained by Navier method. Numerical examples of the FGM sandwich doubly-curved shallow shells are provided for different gradient material parameters, core thicknesses, radii of curvature, aspect ratios, side-to-thickness ratios and vibration modes to demonstrate the accuracy of the present theory.