連続体近似に基づく遅延フィードバックを用いた集中定数系の振幅増大回避

抄録

The vibration control of 5 degrees of freedom spring-mass system as a simple model of the five-layer building by applying delayed feedback force based on continuous system assumption was investigated. The followings are made clear. 1) By applying delayed feedback based on continuous system assumption to a single d.o.f. system is equivalent to adding half-infinite system, and that virtual half-infinite system (VHIS) has characteristic of low pass filter. 2) By adding a support layer that has ten times smaller cut off frequency than the first layer, a clumped boundary become a quasi free boundary. By adding VHISs to both end in addition to adding the support layer, the amplitude enlargement is avoided as follows: (1) If the excitation frequency is lower than a lower cut off frequency among VHISs, the traveling wave passes through both end. Therefore, the standing wave doesn't occur. (2) If the excitation frequency is between a lower and a higher cut off frequency of VHISs, the traveling wave reflects at the end where the VHIS that have lower cut off frequency is attached, but the reflected traveling wave almost passes through at the other end. Therefore, the standing wave is occurred, but the amplitude of the standing wave doesn't enlarge.