Dr. Vance and his graduate students at Texas A&M developed and tested wire mesh bearing dampesr to replace squeeze film dampers (SFD) in turbomachinery. The SFD is the most common type of bearing damper in use today. It has an unfavorable non-linear response and the oil's viscosity is temperature dependent. By replacing the oil film land in the SFD with a short hollow cylinder (donut) made of woven metal strands it is possible to generate damping by the energy dissipation (due to hysteresis) of the material. The first experiments used a metal mesh damper (with no squirrel cage) to support the ball bearing of a power turbine rotor and showed high damping that was independent of temperature or the presence of oil. Rotordynamic experiments were performed later (at speed) with a copper metal mesh damper in parallel with a squirrel cage. These results showed that the squirrel cage allows the stiffness to be readily controlled by the designer with no loss of damping from the metal mesh. Additional experiments were conducted to better understand the mechanism of the damping and to develop design tools for rotordynamic analysis with these dampers. Spreadsheet software was developed for metal mesh damper design, using the experimental data from the test rig. The photo below shows one of the metal mesh donuts. The graph shows how a copper mesh damper reduced the critical speed amplitude in a rotordynamic test rig.

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                Imbalance response of a rotor test rig with and without a copper mesh bearing support




<![if !supportLists]>1)      <![endif]>Ertas, B.H., Al-Khateeb, E., and Vance, J.M., “Rotordynamic Bearing Dampers for Cryogenic Rocket Engine Turbopumps”, AIAA Journal of Propulsion and Power, Vol. 19, No. 4, July-August 2003, pp. 674-682.

<![if !supportLists]>2)      <![endif]>Zarzour, M. and Vance, J.M., “Experimental Evaluation of a Metal Mesh Bearing Damper”, ASME Journal for Gas Turbines and Power (99-GT-15), Volume 112, No 2, April 2000, pp. 326 329.

<![if !supportLists]>3)      <![endif]>Choudhury, V.V., and Vance, J.M., “Design Equations For Wire Mesh Bearing Dampers In Turbomachinery”, GT2005-68641, Proceedings of ASME Turbo Expo 2005, Reno-Tahoe, Nevada, June 6-9, 2005.