Wear testing of aerospace self-lubricating bearing liner materials [Abstract]

The paper describes a novel method for testing the wear rates of liner materials for self-lubricating bearings. The apparatus differs from similar machines in that it is designed for reciprocating contact, to simulate motions encountered in helicopter main rotor pitch link bearings, and is designed to test up to 4 samples at the same time, reducing the effect of variability in environmental conditions. This paper describes key aspects of the test rig along with initial results. Self-lubricating bearings have been in widespread use since the mid-1950s, predominantly in the aerospace industry where they have the advantage of being low maintenance components. They usually consist of a spherical bearing with the inner and outer elements separated by a composite glass fibre / PTFE resin-bonded textile liner. Previous work found that the wear of typical composite liners has three distinct phases – initial wear in, steady-state wear phase, final wear-out, and that humidity and environmental temperature can have a strong influence. Typical bearing-scale tests are long duration, and so a method of accounting for environmental factors and allowing the rapid screening of materials and test conditions is described here as an aid to technology development