円筒形貯水タンクの曲げ振動とオーバル振動との連成に関する有限要素法の併用による等価モデル

抄録

This paper describes the modeling and the numerical simulation to investigate the mechanism of the nonlinear vibration responses of the tank when the beam-type and the oval-type vibrations are coupled. The oval-type vibration accompanies the out-of-plane deformation of the tank sidewall under large input acceleration excitations. So, it is considered that the geometrical nonlinearity due to the oval-type vibrations is the main reason why the vibration responses of the tank are nonlinear. Furthermore, an equivalent nonlinear single-degree-of-freedom (SDOF) system model is proposed to understand the nonlinear vibration responses of the tank, assuming that its flexural rigidity depends on the amplitude displacement of the oval-type vibration. The numerical simulation of the frequency sweep test using this model shows that the resonance frequency decreases as the oval-type vibration becomes larger, suggesting that the proposed model can be effective as one of theories to explain the nonlinear vibration responses of a cylindrical water storage tank.