Rolling elements were the first componentsto be subjected to stochastic life prediction methods. The Weibull life model was adopted by Lundberg and Palmgen as early as 1947 and since then it has been used as the basis of National and International Standards and has gradually been modifed to incorporate emerging knowledge of lubrication and to predict the life increases of the constantly improving bearings. It focueses on the most appropriate failure model of those times, the subsurface-originated atigue. Bearings have however, been continuously improved in terms of design, manufacturing precision, steel integrity and heat treatment and their calculated lives, according to the above methodology, are now seriously under-predicted. Moreover, bearing failures now predominantly occur on the surface.
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