Development of bearings and a damper based on magnetically controllable fluids

Abstract

This paper presents two different kinds of magnetically controllable fluid bearings and a new magnetorheological fluid damper based upon open porous metallic foams. For the bearings, it will distinguish between a magnetohydrostatic bearing and a hydrostatic bearing with a magnetically controllable fluid. The magnetohydrostatic bearings get their load bearing capacity from the magnetohydrostatic pressure that is generated by the gradient of the magnetic field along a fluid surface. With such magnetohydrostatic bearings a specific load up to 1.6 N cm2 can be reached. To support heavier loads hydrostatic bearings with magnetically controllable fluids can be used. This bearing concept makes it possible to achieve a constant bearing gap even if the load of the bearing changes. For this purpose the fluids are used as a hydraulic medium. Due to the magnetically controlled rheological behaviour of the fluid the bearing gap remains constant. The great advantage of this closed loop system compared to that of common hydrostatic bearings using valves is the quicker response to payload changes. The reason for that is that the active element (i.e. the fluid) acts directly inside the bearing gap and not outside like in the case of valves. The foam damper developed uses the fluid to produce controllable damping forces. The open porous foam is directly placed in the active volume of the damper. By moving the foam piston the magnetically controllable fluid is pressed through the pores. The flow in the pores can be controlled by changing the fluid viscosity by applying a magnetic field. With this damper structure it is possible to reach higher damping forces whilst featuring a small design space.

Perancangan Rem Linier Memakai Fluida MR dengan Kendali Arus Listrik Berbasis Fungsi Linier

“…Tanggapan waktu damper MR telah dikaji melalui eksperimen [7]. Perkembangan berikutnya adalah pengembangan busa MR untuk damper [8], [9]. Kinerja tegangan geser dari damper MR berbasis busa metal telah diteliti [10].…”

Analysis of fluid-thermal coupling in ferrofluid bearing used in high speed machines

“…In this paper, magnetic field distribution is assumed to be axial parabolic [3]. Magnetic components are got:…”

“…Ferrofluids also have characteristics of any other fluids [2]. According to above features, ferrofluids can be used in varies areas for different purposes such as sealing, lubricating and heat transfer [3]. Ferrofluid bearing (Fig.…”

Estimation and Active Damping of Unbalance Forces in Jeffcott-Like Rotor-Bearing Systems

“…Due to their low energy consumption, their application in theoretical and practical issues in mechanical systems tends to increase in the last years. Magnetorheological dampers represent the most used semi-active device in rotor systems [3,9,12].…”