Abstract
Magnetic fluids have been around since the 1940s. They come in different forms: magnetorheological fluids (MR fluids) and ferrofluids. MR fluids characterise themselves by having a large change in viscosity under the influence of a magnetic field. Ferrofluids have a significantly smaller change in viscosity, however ferrofluids are colloidal suspensions. After their discovery many applications followed, such as the MR clutch, magnetic damper and bearing applications, in which the fluids are subjected to ultra high shear rates. Little information is available on what happens to the rheological properties under these conditions. In general, the characteristics determined at lower shear rates are extrapolated and used to design new devices. Magnetic fluids have potential in the high tech and high precision applications and their properties need to be known in particular at shear rates around 106 s−1. Commercially available magnetorheometers are not able to measure these fluids at ultra high shear rates and are limited to 105 s−1. Therefore a new magnetorheometer is required to measure ultra high shear rates. In this paper the physical limitations of current measuring principles are analysed and a concept is designed for ultra high shear rate rheometry in combination with a magnetic field. A prototype is fabricated and the techniques used are described. The prototype is tested and compared to a state of the art commercial rheometer. The test results of the prototype rheometer for magnetic fluids show its capability to measure fluids to a range of 104 s−1– s−1 and the capability to measure the magnetorheological effect of magnetic fluids.
Highlights
Magnetic fluids come in different forms with different properties
They are known as magnetorheological fluids (MR fluids) and ferrofluids
Preliminary test been varied from −3 A to 3 A whilst measuring the magnetic field density, figure 19
Summary
Magnetic fluids come in different forms with different properties. They are known as magnetorheological fluids (MR fluids) and ferrofluids. In the 1940s Jacob Rabinow created the first MR fluid. These MR fluids alter their rheological properties (viscosity) significantly under the influence of a magnetic field. The first use of ferrofluids is credited to Papell while working for NASA in 1963 [1]. Ferrofluids have significantly less change in their viscosity, are the first magnetic fluids that are colloidal suspensions [2,3,4].
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.