Hybrid Ceramic Bearing Fatigue Testing for the Future Advanced Rotorcraft Drive System Program

Today's rotorcraft transmissions predominately utilize fully metallic bearings where both the raceways and rolling elements are metal. Ceramic bearing materials offer the potential for meeting the demand for weight reduction and increased power-to-weight ratios. Hybrid ceramic bearings incorporate both ceramic and metallic components forming an assembly that lends itself to improvements in weight, corrosion resistance, reduced friction, and improved surface characteristics. Typically, hybrid ceramic bearings consist of ceramic rolling elements and metallic raceways. Hybrid ceramic bearings have demonstrated feasibility for both remotely and non-remotely monitored applications in rotorcraft drive systems. Characterization of potential material combinations of hybrid ceramic bearings is needed to guide the design of hybrid ceramic bearings for use in future and modified rotorcraft transmissions. This research, conducted under the Future Advanced Rotorcraft Drive System (FARDS) program, examined multiple bearing material combinations and characterized them in fatigue testing. Hybrid ceramic bearing material combinations showed increased performance when compared to fully metallic bearing material combinations. Favorable results indicate that hybrid ceramic bearings can have immediate impact on rotorcraft transmission designs.