Summary
A phenomenon called passive self-tuning resonance can be found during excitation of a system consisting of a beam and a moving mass. In this phenomenon, due to the nonlinear coupling between the vibration of the beam and the motion of the mass, the mass can move passively to one of the anti-nodes of some vibration mode along the beam under excitation, and as a result, the entire system can resonate. In this study, magnetic support utilizing the pinning effect of the superconductor is applied to this system with an eye to the application of this phenomenon to energy harvesting through vibrational power generation. The non-contact elastic support by nonlinear magnetic force is expected to increase the amplitude and the frequency bandwidth of the resonance, which may be advantageous for vibrational power generation. Through excitation experiments, it was observed that passive self-tuning resonance can occur even in magnetically supported systems. The amplitude of the resonance was larger than that of the fixed-supported system. Furthermore, resonance was observed over a wide frequency bandwidth under the excitation near the natural frequency of the second mode. According to the measurement results of the vibration mode shapes and frequencies, it was confirmed that the behavior of the system transitioned from the resonance of the second mode to the resonance of the first mode during the process of excitation. This may have been caused by nonlinear coupling of multiple modes.
