Development and Design of New Magnetic Damper Based on Magnetic Seesaw Phenomen

本研究项目的目的是建立一种基于村上博士提出的“磁跷跷板现象”的新型磁振阻尼器的设计方法。这种磁阻尼器的优点是不仅具有微震动等小振动的减振能力，而且具有地震反应等大激励的减振能力。基于“磁跷跷板现象”所建立的设计准则，制作了3种试验磁阻尼器，通过改变阻尼器直线滑动运动的步长，设计出不同的磁阻尼能力。为了检验阻尼-频率特性，进行了正弦和随机输入运动的振动试验。通过试验，估计了复合横摆数、横摆与磁极的关系以及获得期望磁阻尼能力的间隙宽度的最佳设计条件。并进行了理论研究。根据永磁体的“磁导率”特性建立数学模型，并将其应用于永磁体的设计。利用该模型进行了数值模拟，评估了其频域阻尼特性。至少在这个特定的研究项目所采用的条件下，结果与试验结果吻合得很好。未来面临的挑战是将该研究发展到更一般的情况，其中振动条件变得更加扩展，并且必须考虑阻尼装置中的摩擦和间隙运动等非线性效应。

The purpose of the research project is to establish a design method of a new magnetic -vibration damper based on a "magnetic seesaw phenomena" which was proposed by Dr. Murakami. The advantage of this magnetic damper is to possess a capability for reducing vibration not only small on such, as micro tremor but also large excitation such as seismic response.1. Based on the established design criteria due to "magnetic seesaw phenomena", 3 kinds of trial magnetic dampers were manufactured, each of which were designed to produce different magnetic damping capacity by changing a step length of linear sliding motion of the dampers.2. In order to examine the damping ― frequency characteristics, shaking test was carried out by sinusoidal and random input motions. Though the testing, optimum design conditions to the number of laminated yawks, the relation between yawks and magnetic poles and the gap width for getting the expected magnetic damping capacity were estimated.3. Theoretical investigation was also performed. Mathematical modeling was constructed based on "permeance" behavior which has been used in the design of the permanent magnet. Through numerical simulation by using this model, damping characteristics in the frequency domain were evaluated. The results quite well agreed with the testing results at least under the conditions adopted in this particular research project.4. Future problems to be challenged is to develop this research to more general cases whereby vibration condition becomes much more expanded and nonlinear effects such as friction and gap motion in the damping devices have to be considered.