Magnetorheological damper

Amagnetorheological damperormagnetorheological shock absorberis adamperfilled withmagnetorheological fluid, which is controlled by amagnetic field, usually using anelectromagnet.This allows the damping characteristics of theshock absorberto be continuously controlled by varying the power of the electromagnet. Fluidviscosityincreases within the damper as electromagnet intensity increases. This type of shock absorber has several applications, most notably insemi-activevehicle suspensionswhich may adapt to road conditions, as they are monitored through sensors in the vehicle, and inprostheticlimbs.
Many applications have been proposed using magnetorheological (MR) dampers. While vehicle applications are the most common use of MR dampers, useful medical applications have risen as well, including implants and rehabilitation methods.Since MR dampers are not yet perfect, they are limited in terms of application. Disadvantages do exist when using a large scale MR damper, for example, particle settling within the carrier fluid may occur that inhibits some possible application.
The technology was originally developed by General Motors Delphi Automotive Division based in the USA and then developed further by BeijingWest Industries in China after BeijingWest Industries bought the technology from General Motors. BeijingWest Industries has subsequently introduced improvements including a redesigned ECU and the introduction of a dual coil system. The first car to use the technology was the 2002.5 Cadillac Seville STS, and the first sports car to use the technology was the 2003C5 Corvette.
These types of systems are available from OEMs for several vehicles, including theAcura MDX,Audi TTandR8,Buick Lucerne,Cadillac ATS,CTS-V,DTS,XLR,SRX,STS,Chevrolet Corvette,Camaro ZL1,Ferrari 458 Italia,599GTB,F12 Berlinetta,Mustang Mach-E,Shelby GT 350,Holden HSV E-Series,andLamborghini Huracán.These systems were produced by theDelphi Corporationand now byBWI Groupunder the proprietary nameMagneRide.
MillenWorkshas also included them in several military vehicles including theMillenWorks Light Utility Vehicle, and in retrofits to theUS ArmyStrykerandHMMWVfor testing byTARDEC.
MRF-based dampers are excellent candidates for stability augmentation of the lead-lag (in-plane bending) mode of rotor blades in helicopters.MRF-based squeeze film dampers are being designed for use in therotary wingindustry to isolate vibrations from the aircraft structure and crew.
A magnetorheological damper is controlled by algorithms specifically designed for the purpose. There are plenty of alternatives, such as skyhook or groundhook algorithms.The idea of the algorithms is to control theyield point shear stressof the magnetorheological fluid withelectric current. When the fluid is in the presence of an appliedmagnetic field, the suspended metal particles align according to thefield lines.Viscosityof the fluid increases according to the intensity of the magnetic field. When this occurs at the right instant, the properties of the damper change helps in attenuating an undesired shock or vibration. The relative efficacy of magnetorheological dampers to active and passive control strategies is usually comparable.