Nonlinear Vibration and Numerical Simulation of a Cylindrical Liquid Storage Tank (Nonlinear Behavior of Oval-Type Vibration)

This paper describes a nonlinear behavior of oval-type vibration in a cylindrical liquid storage tank which is high order vibration mode in the circumferential direction of the wall (axial half wave number m ≥ 1 and circumferential wave number n ≥ 2). When the vibration experiment of a cylindrical liquid storage tank was conducted by exciting its base, a nonlinear behavior of oval-type vibration occurred. At large excitation, oval-type vibration with sub-harmonics of order one-half occurred as well as that with the fundamental harmonics. Frequency analysis showed the oval-type vibration with sub-harmonics was dominant. The result demonstrated the nonlinearity of oval-type vibration. The nonlinear behavior of oval-type vibration was dynamically simulated by nonlinear explicit finite element analysis method considering fluid-structure interaction as well as large deformation. The numerical analysis results showed the same oval-type vibrations with fundamental harmonics and sub-harmonics of order one-half occurred as those in the experiment, that is, analytical vibration modes coincided with the experimental modes. It can be concluded the proposed numerical analysis method can simulate the nonlinear behavior of oval-type vibration accurately.