Rolling Bearing Reliability Assessment via Kernel Principal Component Analysis and Weibull Proportional Hazard Model

Table 2

Point messages.

Period	Point	Date (day)	Characteristics
Normal working stage		0–17.69	The features are in normal range.
		17.69–28.99
		28.99–31.05
Early failure stage		31.05–32.53	When the surface defect just initiates, small spalling or cracks are formed. Kurtosis has great fluctuation, but RMS increases slowly [31].
		32.53–33.34
Healing stage		33.34–33.49	The surface defect is later smoothed by the continuous rolling contact. The vibration level decreases.
Medium wear stage		33.49–34.11	As the damage spreads over a broader area, the vibration level rises again.
Severe wear stage		34.11–34.17	As the damage spreads over an enough area, the vibration level rises quickly.