Ceramic hybrid bearings are like conventional bearings, except the steel rolling elements have been replaced with ceramic elements. The ceramic rolling elements in hybrid bearings offer many benefits, including low density, high hardness, low thermal growth effect, corrosion resistance, and favorable frictional characteristics. However, damage detection for ceramic hybrid bearings has been an issue for the aerospace industry since their introduction. In the aerospace industry, lack of an effective and reliable method for damage detection limits the immediate use of ceramic hybrid bearings to applications that are not remotely monitored. One such application is the helicopter tail rotor driveshaft hanger bearing. Typically, tail rotor driveshaft hanger bearings have no in-flight damage detection system. Bearing damage is detected by manually rotating the bearing and feeling for any perceived roughness. Hanger bearings are often configured as sealed grease packed bearings. Many of these bearings also have means provided for re-greasing. The object of this paper is to present the results of a series of tests designed to determine the suitability of ceramic hybrid bearings in helicopter hanger bearing applications. The discussion shall include the results of 100 hour and 200 hour side-by-side hybrid and steel bearing endurance tests. In addition, the results of a 100 hour "run dry" hybrid bearing test, conducted at the same load and speed as the endurance test, is presented. Finally, ceramic hybrid bearing failure modes are discussed, damage detection methods for hanger bearing applications are proposed, and data taken from a single, extreme load test is discussed.
Evaluation testing of ceramic hybrid bearings for helicopter hanger bearing applications
2006
12 Seiten, 3 Quellen
Aufsatz (Konferenz)
Englisch
Evaluation Testing of Ceramic Hybrid Bearings for Helicopter Hanger Bearing Applications
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