Tribological failure analysis of a heavily-loaded slow speed hybrid journal bearing

•Experiments conducted on magnetic & hybrid bearings for heavy load and slow speeds.•Theoretical magnetic levitation force determined for magnetic bearing arrangements.•Cylindrical magnetic bearing unable to levitate the rotor under static condition.•180° arc and hybrid bearing failed to maintain levitation in dynamic conditions.•Hybrid bearing resulted in less severe wear compared to 180° arc magnetic bearing.

In the present work, the feasibility of hybridizing a magnetic arrangement in the conventional journal bearing system has been experimented for the operating conditions of heavy load and slow speed. A test setup has been developed to perform testing on four types of bearing arrangements: conventional journal bearing arrangement, cylindrical magnetic bearing arrangement, circular arc (180°) magnetic bearing arrangement and a hybrid bearing arrangement. The magnetic levitation force was determined theoretically for these arrangements to identify reasons for the mechanical contact between rotor and stator magnets. The results of the experimental investigations in terms of the weight loss (wear), reduction in the magnetic flux density, acceleration signals, and photographs of worn & fractured rotor are reported.