208 高温超電導磁気浮上系における係数励振的振動の線形動吸振器による低減

Abstract

This research deals with numerical analysis of effects of a vibration absorber on the amplitude of nonlinear oscillation in a high-Tc superconducting magnetic levitation system. High-Tc superconducting levitation systems have very low damping and stable levitation without control. In such low-damped systems, complicated phenomena of dynamics can be easily generated by nonlinearity of the magnetic force. Our previous research showed that, if the frequency of vertical excitation is in the neighborhood of double the natural frequency in the horizontal direction, horizontal oscillation can occur parametrically through nonlinear coupling between vertical motion and horizontal motion. This research investigates an effect of a vibration absorber on the parametrically excited horizontal oscillation of the levitated body. We calculated numerically the dynamics of the rigid body which is levitated by the magnetic force acting between superconductors, which are fixed on shake table, and magnets, which are fixed to both the ends of rigid body. A simple damped horizontal pendulum is attached to the main system as a vibration absorber, so that it is linearly coupled with horizontal motion of the main system. Numerical results proved that this kind of vibration absorber is effective in reducing the amplitude of a parametric resonance in a high-Tc superconducting levitation system.