Bill Beckman December 9 th, 2013 Wear of a Gas Turbine Friction Damper MANE-6960 Friction, Wear, and Lubrication of Materials

Overview Wear of a dry friction damper in turbine section of engine investigated Blade excitation is one of many failure concerns due to risk of cyclic crack propagation from dynamic loading coupled with high thermal and static loading Turbine blade vibration amplitude mitigated by use of under platform cottage-roof damper to dissipate kinetic energy by means of frictional contact and heat generation

Theory and Methodology

Results Various hardness values of high temperature alloys have an effect on damper wear rates Nickel and Cobalt-Chromium alloy hardness can range from 165 BHN to 515 BHN in a high temperature environment Surface modification by means of carburization can be an effective low cost solution over high bulk material hardness alloys

Conclusion Adhesive wear due to plastic deformation of asperity and bulk material cannot be avoided over high cyclic loading Increasing material hardness retains damping capability of the part over lifetime of engine operation Gas carburizing further improves part capability Softer and lighter Ni alloy can behaves as high hardness Co-Cr alloy for most of part lifetime Damper volume lost over lifetime 165 BHN 235 BHN 305 BHN 375 BHN 445 BHN 515 BHN Carburized 19.8%14.5%11.5%9.6%8.2%7.2%9.8%