Author(s)

A. Maekawa & K. Fujita

Abstract

This paper describes the numerical simulation of nonlinear oval-type vibration in cylindrical water storage tanks. Oval-type vibration is a high-order vibration mode in the circumferential direction of the tank wall (axial wave number m ≥ 1 and circumferential wave number n ≥ 2 ). In our previous vibration experiment in which large excitation was applied to the base of a cylindrical water storage tank, the nonlinear behavior of oval-type vibration occurred. Under large excitation, nonlinear oval-type vibration with sub-harmonics of order one-half occurred, as well as oval-type vibration with fundamental harmonics. The nonlinear behavior of oval-type vibration was simulated by the numerical analysis method proposed in this paper, which allowed coupling analysis between the fluid and structure and large deformation analysis to be considered. The analysis results were compared with experiment results, and the analytical vibration behavior coincided with the experimental behavior. Accordingly, it was concluded that the proposed numerical analysis method could accurately simulate the experiment. Keywords: numerical simulation, nonlinear vibration, oval-type vibration, subharmonics of order one-half, coupling analysis between fluid and structure, cylindrical water storage tank. 1 Introduction It is well known that a coupled vibration system is formed between the tank structure and the contained water in cylindrical water storage tanks, causing complex vibration behavior (Shibata et al. [1]). In the coupled vibration system, the natural frequencies of both beam-type vibration (axial wave number m ≥ 1

Keywords

numerical simulation, nonlinear vibration, oval-type vibration, subharmonics of order one-half, coupling analysis between fluid and structure, cylindrical water storage tank.