Fatigue life reduction of roller bearings due to debris denting: Part II -Experimental validation

Life tests have been conducted for tapered roller bearings. Bearing race wa ys are pre-dented with particles of various types and sizes. Life reduction s due to surface indentation are calculated by a stress-based life model us ing the measured raceway topography. The predictions are compared and valid ated with testing results. The study concludes that bearing life reduction is primarily determined by the slopes and area densities of surface indenta tions. Life reduction factor decreases as dent slope and area-density incre ase. The hardness and fracture toughness of the denting particles have a no ticable effect on bearing life reduction. Ductile particles cause more seve re life reduction than the brittle particles. Surface failures associated w ith small dents are superficial and often appear in forms of "micro-pitting " and "micro-peeling." Large dents generated by ductile particles cause sev ers damage to bearing raceways and are more likely to induce surface pits a nd spalls.