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

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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.