NATURAL FREQUENCIES AND MODE SHAPES OF 2 COAXIAL CYLINDRICAL-SHELLS COUPLED WITH BOUNDED FLUID

Coaxial shells or cylinders containing fluid have been widely used as structural components in various applications. Several previous invest igations have been performed to analyze the foe vibration of fluid-fil led, coaxial cylindrical shells. However, previous theories were limit ed to the approximated methods and could provide only the in-phase and out-of-phase modes of coaxial shells with small annular fluid gap com pared to the shell diameters. Therefore, the previous theories can onl y be applicable to the low axial and circumferential modes of coaxial shells with small annular fluid gap. Practically, there exist many amb iguous vibrational modes in addition to the in-phase and out-of-phase modes. In this paper, an advanced general theory is developed which ca lculates the natural frequencies for all vibrational modes of two coax ial circular cylindrical shells coupled with fluid. To support the val idity of the proposed theory, a finite element modal analysis was carr ied out for the clamped/clamped boundary condition. Excellent agreemen t was obtained between the analytical solution and the finite element analysis. (C) 1998 Academic Press.