Passive magneto-rheological vibration isolation apparatus using a shielding sleeve

Patent US7628254

Description

AFRL has developed a damper containing magneto-rheological ("MR") fluid.  A plunger that lies between has a head immersed in the MR fluid and is mechanically coupled both to a fixture and a vibration source.

A problem often faced in the field of engineering is vibration isolation. A fairly recent active material development is magneto-rheological ("MR") fluid. MR fluids are comprised of micron sized, magnetically-polarized particles suspended in a carrier fluid. When activated by a magnetic field, the particles align along magnetic field lines and change the material's flow characteristics, such as its viscosity and bulk modulus. By varying the magnetic field flux acting on the MR fluid, the viscous damping may be modulated.

Abstract

A damper containing magneto-rheological (“MR”) fluid and a plunger lies between and is mechanically coupled both to a fixture and a vibration source. The plunger has a head immersed in the MR fluid. Annular magnets circumscribe the damper and produce a magnetic field surrounding the damper. A tubular shielding sleeve composed of magnetically impermeable material surrounds a portion of the damper. The sleeve is mechanically coupled both to the fixture and the vibration source by springs, and can translate relative to the damper to affect the strength of the magnetic field acting on the MR fluid surrounding the plunger head. The sleeve oscillates responsive to vibration of the vibration source and controls the viscosity of the MR fluid surrounding the plunger head in proportion to the amplitude of the sleeve's oscillation. The resonant frequency of the sleeve is adjusted to approximate the fundamental resonance of the fixture.

  • Transportation (ground vehicles, aerospace vehicles)
  • Vibration isolation in instrumentation or optical tables
  • Applications which have a need to mechanically decouple a mass from the vibrations found in its environment

TECHNOLOGY READINESS LEVEL (TRL)

TRL 3: Analytical and experimental critical function and/or characteristic proof of concept Active R&D is initiated. This includes analytical studies and laboratory studies to physically validate the analytical predictions of separate elements of the technology. Examples include components that are not yet integrated or representative.
Air Force Research Laboratory- Space Vehicles Directorate (RV) logo

Air Force Research Laboratory- Space Vehicles Directorate (RV)

Kirtland AFB, NM

Advantages

  • Vibration isolation over a broad frequency spectrum
  • Passive control system (simpler and self-contained)