73 巻 (2007) 736 号 p. 3179-3184
In this paper, the authors propose a new type hybrid damper with effect of magnetization and demagnetization. The damper consists of a ball screw, electromagnets, rare-earth magnets, and a conductive disk. The core of the electromagnet is combined with the rare-earth magnet. It is called a hybrid electromagnet. The damper has a controllable damping force that is magnetized in case of positive magnetic fields created by the electromagnet, otherwise demagnetized in case of negative one. The validity of the damper is to utilize by a fail-safe mechanism at a time when electric power is lost under the device malfunction. In order to investigate the resisting force characteristics of the damper, the vibration tests are carried out. The test damper has a function of increasing and decreasing magnetic flux density from a neutral position. The experimental results well agree with the theoretical results. Next, to estimate the damping effects of the damper, a one-degree-of-freedom system which is connected to the damper is proposed here. The simulations of seismic response under a semiactive control based on Linear Quadratic Regulator are calculated, and the damping effects of the damper are confirmed numerically.