Study on active damper with a magnetic fluid

Study on control of vibration of a spring-mass system by using a magnetic f luid is conducted. The system consists of a cylinder filled with a magnetic fluid, a piston immersed in the magnetic fluid and a weight attached to th e piston. The cylinder connected to the weight by a spring is excited to vi brate. The magnetic field necessary for stopping vibration of the mass is p redicted. Validity of the prediction is proved by numerical experiments, wh ere the equation of motion for the spring-mass system and the axisymmetric flow of the magnetic fluid are simultaneously solved. The magnetic field ge nerated by a couple of coils can effectively damp the transient vibration a nd control the steady vibration to be extremely small.