Magnetic Vibration Damper for Space Applications

1. Magnetic Vibration Damper for Space Applications P11566 20101 / 20102 Mission: To develop a prototype of a solid state eddy current damper for use in satellite and aerospace applications and to deliver it with an accurate analytical model of system performance and test fixture in 25 weeks. • Background Principle: When a conductor moves through a magnetic field, an eddy current is generated (like a paddle through water) which dissipates mechanical energy as electrical current through the conductor. The motion of the damper will behave according to the equation of motion for a spring-damper system, shown below. The zeta calculation referenced in customer needs backs out of the ‘c’ damping coefficient. • Concept Generation: • Magnets fixed, conductor mobile • Conductor fixed, magnets mobile • Design Selection: The first method was chosen to minimize magnetic leakage. The magnet array is mounted on a cast iron bridge to amplify the magnetic field strength and allows a copper vane to move between to dissipate the energy in the system. The motion is constrained by a set of laser cut flexures. The design sought to maximize use of off the shelf parts. • The magnets used are rare earth, neodymium magnets, rated at 14,800 Gauss with a pull force of ~40 lbs. Very strong. Copper vane is free to move through magnet array. Flexure constrains motion Layers promote easy modification Test fixture with unit attached to shaker table …before the test caused the shaker to overheat. Cast iron bridges magnetic field, amplifies power greatly • Known issues: • During testing it was difficult to find a consistent method to vibrate the damper. • While exploring different options and trying different techniques, a shift in the magnetic array caused rubbing. • It is unknown whether the model matches the prototype, or what level the prototype was performing at before the array shift happened. • Unit is very heavy, assumptions were made that the actual unit would contain aero grade materials. • Unable to test at temperature extremes or in vacuum. • Proposed Work: • Use non-conductive magnetic bridge to make simpler magnetic field. • Attempt to design to last for proposed life cycle. • Make continuous strides to reduce weight of the unit. • Consider designs that would reduce possibility of rubbing. • Consider trade off of swapping copper for aluminum conductor (conductivity vs. weight). • Effect on damping coefficient from increasing magnet layers. Theoretical eddy current produced from conductor moving through a pair of magnets at 0.5 in./sec (from COMSOL). Team (left to right): Jake Norris (ME)- Fabrication Engineer Tom Sciotto(IE)- Lead Engineer Tiffany Heyd(ME)- Simulation Engineer Ben Hensel(ME)- Test Engineer Dr. Alan Raisanen- Faculty Guide Special Thanks to: Phil Valloneof ITT Rob Kraynikand the entire ME shop staff Dr. Linda Barton Dr. Marca Lam Dr. Mark Kempski Dr. P. Venkataraman