Development of magnetic dynamic damper for nuclear power plant

This paper describes a magnetic dynamic damper (MDD), which is a passive vi bration absorber employing a permanent magnet and a conductor for both the restoring and damping force. The basic characteristics of this magnetic spr ing and damper system are examined through static loading tests and vibrati on tests using a pair of double cylindrical magnets. It is confirmed that t he magnetic force analysis accurately simulates these test results. Applica tion of this system to a rotating machinery model shows that the MDD can ef fectively reduce two-dimensional vibration. Moreover, through the forced vibration test in which MDD is attached to the bottom of vertical pump, it is examined that the proposed MDD can be appli cable for seismic response reduction over the wide region of pump casing di splacement. The top heavy valve equipped on piping vibrates biaxially at different freq uencies. In this case, it is confirmed from the vibration tests using a val ve-piping model that the MDD with multiple rectangular magnets is effective in reducing two-dimensional vibration with different frequencies.