Underwater robotic vehicles (URVs) normally use mechanical seals with o-rings, rubber boots, PTFE or Grafoil wedges, or V-rings. Because mechanical seals can cause an unexpected malfunction, we try to adapt magnetic fluid seal (MFS) for underwater robotic vehicles. For reliable design of the MFS, we use numerical simulation of the flow in the MFS using finite element method. The results obtained from experimental investigations of the operation of the MFS contacting with pressurized water will be compared to numerical simulation results

A magnetic fluid simultaneously has hydrodynamic and electromagnetic properties because its characteristics depend on whether a magnetic field is applied or not. The studies conducted so far on actuators that use a magnetic fluid are insufficient. A magnetic fluid has an added advantage in that it can be applied to small or micro systems because of its nanoscale particle size. Therefore, this research investigated the braking characteristics of a small disk brake that used a magnetic fluid. First, magnetostatic analysis of the magnetic field produced by a permanent magnet was conducted, and then, the pressure distribution in the magnetic acted upon by the magnetic body force from the permanent magnet was analyzed using the governing equations of a magnetic fluid. So, in this research, the torque characteristic of small disk brake by a magnetic body force was studied through the relation between the magnetic field intensity and rotational disk velocity. In addition, the torque characteristics of the brake due to a magnetization of the magnetic fluid were confirmed experimentally.

The predominant failure modes (wrinkling and tearing) must be avoided during the drawing process in sheet metal forming. These defects may be eliminated by using a controllable device for which the blank holding force (BHF) is adjustable. The purpose of this research is to verify the possibility of using a magneto-rheological (MR) damper for obtaining an almost constant BHF in drawing presses. The damper force is controlled by adjusting the current that is applied to the MR fluid, which is a functional material. To realize this aim, a prototypical press system is manufactured. A control test using a closed-loop PID controller is carried out for achieving the objective where by a constant BHF is retained at a constant prescribed force, while the press slide translates at a constant velocity. The results show that the BHF of the drawing press can be controlled effectively by using the proposed MR damper.

ABSTRACT

This research analyses the dynamic behavior of magnetic fluid that sloshes due to the pitching motion of the container. To analyze the behavior of magnetic fluid, we first analyze the equations that govern magnetic fluid as well as the momentum equation of the sloshing that results from a magnetic field. In each case, we conducted simulation and compared the results from simulation with those from experiments. When sloshing does not occur, the surface of the magnetic fluid rises towards the location of intensity of the magnetic field; in the absence of an additional, external body force, the fluid remains elevated. In case sloshing occurs simultaneously with the application of the magnetic field, the elevation of the surface as a result of the magnetic field is maintained. Further, we can confirm that if the excitation frequency of sloshing is small, the wave motion of the surface is small because the magnetic body force dominates the effect of sloshing. Even if the excitation frequency increases, the wave motion of the fluid surface is smaller than when a magnetic field is not applied. The fluid surface rises in that location where the intensity of the magnetic field is strong. Where the intensity of the magnetic field is weak, the height of the fluid surface is lower than the initial level that obtains in the absence of a magnetic field. Through the study, we can conclude that the sloshing behavior of magnetic fluid is influenced by the magnetic field intensity and distribution.