Free Vibration of Axisymmetric Thin Oblate Shells Containing Fluid


A theoretical analysis for the free , axisymmetric, vibrations of an isotropic thin oblate spheroid shell filled partially or completely with an incompressible, non-viscous, irrotational fluid is considered. The Rayleigh – Ritz's method is used to obtain an approximate solution which coincides with the exact solution for the cases of an empty orcompletely filled shell. The vibration of the shell is examined using the non – shallow shell theory. The analysis is based on considering the oblate spheroid as a continuous system constructed from two spherical shell elements matched at the continuous boundaries. Solutions are presented to show the effect of the angle of filling fluid on the shell natural frequencies.The effect of shell geometric parameters on the frequencies is also investigated. Natural frequencies are calculated for the shell in both empty and filled cases. It was found that their frequencies are decreased with the increase of fluid level in the shell. The analyticalsolution is compared with available test results. Good agreement is shown between test results found in the literature and predicted natural frequencies.