Bearing life prognosis under environmental effects based on accelerated life testing

Abstract

Abstract

The reliability of a bearing is typically estabilished by repeated life testing which provides valuable information on the fatigue mechanisms from crack initiation, crack propagation to flake or spall. Under nominal operating conditions, life testing often consumes a significant amount of time and resources, due to the comparatively high bearing mean lifetime before failure (MTBF), rendering the procedures expensive and impractical. Therefore, the technology of accelerated life testing (ALT), which is widely used in manufacturing practice, offers the attractive benefit of requiring relatively less investment in terms of time and resources. Data from tests at high stress levels (e.g. temperature, voltage, pressure, corrosive media, etc.) can be extrapolated, through a physically reasonable statistical model, to obtain life estimates at lower, normal stress levels. In this study, a methodology to predict bearing lifetime under a corrosive environment has been developed based on accelerated life testing data and the application of the inverse power law. Bearing life tests under various corrosion stress levels were performed for model identification followed by additional independent bearing life tests conducted for model verification. The experimental result shows that the accelerated life test model can effectively assess the life probability of a bearing based on accelerated environmental testing, even with extrapolation to untested stress levels.