Magnetorheological Fluid-based Damper Research Articles

Non-linear analysis of a typical nose landing gear model with torsional free play

One of the problems faced by the aircraft community is the landing gear dynamics, especially the shimmy. Non-linear behaviour of landing gear makes the evaluation of the shimmy phenomenon more complex and its prediction more difficult. Notably the non-linearities in landing gear torsional free play tend to destabilize the landing gear, whereas the frictional non-linearity dissipates energy and thus increases the landing gear stability. This article presents the study of the shimmy instability of a typical nose landing gear model developed based on the Li formulations with torsional free play. Finally, the study has been performed to postpone the dynamic instability by introducing magneto rheological fluid-based damper.

Wear Testing of Seals in Magneto-Rheological Fluids©

Magneto-rheological (MR) fluid-based dampers can be used in suspensions to modify ride, handling, and suspension frequencies in autos. We have developed a unique seal wear test method to simulate the wear of rod seals in Magneto-rheological fluid-based dampers. In this test, seal material samples in the form of rectangular coupons are immersed in a bath of MR fluid, and a section of the rod is brought into contact with the seal coupon. The rod is loaded against the coupon with a known normal force, and a variable-frequency reciprocating machine is used to stroke the rod back and forth across the material coupon surface. Test conditions such as normal load, frequency and amplitude of oscillation, and temperature are adjusted to simulate desired conditions. This bench test method ranks various seal materials qualitatively in the correct order (as determined in field tests with these seal materials) in terms of wear and abrasion resistance and constitutes a valid test procedure for the screening of seal materials, MR fluids, and rod surface coatings.

Comparative Analysis of the Time Response of Electrorheological and Magnetorheological Dampers Using Nondimensional Parameters

Electrorheological (ER) and magnetorheological (MR) fluids show similar field-dependent rheological characteristics from a bulk fluid perspective. However, the implementation of ER and MR fluids in devices may require different strategies because of the inherent properties of ER and MR fluids such as density, viscosity and the magnitude of the yield stress. Therefore, in this study, we explore the characteristics of ER and MR fluid-based systems on the basis of dynamic range and time response in order to comprehensively understand each system. In doing so, a nondimensional analysis, based on parallel plate geometry, is used to characterize the field-dependent properties of ER and MR fluid-based dampers. Experimental tests are conducted for ER and MR dampers in order to validate our analysis.