Free vibration analysis of FGM circular cylindrical shells resting on the Pasternak foundation and partially in contact with stationary fluid

This paper deals with free vibration problem of ceramic and metal functionally graded circular cylindrical shells embedded in a Pasternak elastic foundation and partially/completely in contact with a fluid within the framework of the first-order shear deformation theory. The fluid is considered to be ideal which its irrotational motion can be described by a velocity potential function. In the analysis, to simplify the interaction between the shell and the fluid, the effects of hydrostatic pressure and free surface waves are neglected. Mechanical properties of the functionally graded cylindrical shell are assumed to be graded in the radial direction and follow a power law pattern of the volume fraction of the constituents. To calculate the natural frequencies of the wet cylindrical shell, the modal displacement functions in the longitudinal direction are defined as a set of Chebyshev polynomials multiplied by a boundary function in the Rayleigh-Ritz method. To demonstrate the accuracy and validity of formulation, comparisons are made with the reference solutions. The effects of fluid depth ratio, elastic foundation, volume fraction exponent, geometrical parameters and boundary conditions on the natural frequencies are discussed in detail. (C) 2019 Elsevier Ltd. All rights reserved.