This paper has compared the use of ER and MR fluids for the design of aircraft landing gear shock absorbers. The aim was to optimise ER/MR valves within the geometrical constraints of an existing passive shock strut. As a case study, a telescopic landing gear designed by Messier Dowty for a large-scale aircraft was chosen. It was shown that to maximise the performance of a geometrically constrained MR valve, multiple valve stages should be incorporated. For an ER valve, multiple duct designs should be used to overcome the inherently low maximum yield stress, which can be arranged in series or parallel. The MR device maintained a significantly superior performance, in spite of using multiple duct ER configurations. For example, larger control ratios meant that a wider range of impacts could be optimally damped. A series ER valve configuration performed reasonably well, although very large voltages of up to 8kV were required. As with the MR valve, the maximum Reynolds number was also very high. This could cause performance to suffer if turbulence occurs, but further work is required to validate this. Parallel duct designs could be used to lower the maximum voltage and Reynolds number, but this is at the expense of the control ratio. A key advantage of using ER fluids in landing gears is their lower mass. For example, it was found that a single shock strut could be 12kg lighter than an equivalent MR design. However, it is unlikely that the associated trade off in performance would be acceptable. One promising development that could potentially overcome this is the use of high yield stress ER fluids. Researchers at the Hong Kong University of Science and Technology have developed ER fluid suspensions of nanoparticles that can reach yield strengths of up to 130kPa. Such fluids could simultaneously enable high levels of controllability, and modest voltage requirements.
Semi-active landing gear incorporating smart fluid damping: A performance comparison of ER and MR fluids
Halbaktives Flugzeugfahrwerk einschließlich intelligenter Flüssigkeitsdämpfung: Leistungsvergleich zwischen elektrorheologischen und magnetorheologischen Fluiden
2007
10 Seiten, 7 Bilder, 4 Tabellen, 19 Quellen
Aufsatz (Konferenz)
Englisch
The application of a smart landing gear oleo incorporating Electrorheological fluid
Tema Archiv | 1998
|An Electrorheologically Controlled Semi-Active Landing Gear
SAE Technical Papers | 1993
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