关键词: 磁性液体密封, 屈服应力, 启动扭矩, 链状结构

Abstract: Magnetic fluid seal is the most mature application of magnetic fluid. The sealing performance of magnetic fluid seal changes with the extension of standing time, especially the phenomenon that the starting torque of the magnetic fluid seal increases with the extension of standing time may cause difficulty in starting the seal or even damage. In order to explore the mechanism of this phenomenon, the relations among the starting torque of magnetic fluid seal with temperature, standing time, the amount of magnetic fluid injected and the pressure exerted on the magnetic fluid are experimentally studied, and the changing reasons of the starting torque of magnetic fluid seal are theoretically analyzed. The results show that the lower the temperature is, the longer the standing timeis , the greater the amount of magnetic fluid injected is, and/or the lower the pressure is, the greater the starting torque is. The essence of this phenomenon is thatthe particles in magnetic fluid form chain-like structures under the action of magnetic field. Yield stress needed to break chain-like structures is the cause of changing starting torque.

Key words: magneticfluidseal, yieldstress, startingtorque, chain-likestructure