CFD investigation of starvation behaviors in a grease lubricated EHL rolling contact

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Nowadays, more than 90% of all rolling element bearings are grease lubricated. Grease releases oil to separate the contacting surfaces by forming a stable oil film, thus resulting a long service life of a bearing. The film thickness is usually calculated by assuming fully flooded conditions. However, if the amount of released oil is insufficient, the film thickness will be reduced, which is termed as starvation. Grease lubricated rolling bearings have the risk of starvation even at fairly moderate speeds, which implies a high risk of wear and bearing failure. To reduce this risk, an accurate starvation model to predict film thickness under starvation is needed. In this contribution, a new starvation model based on the CFD method is used. The effects of starvation on film thickness and surface deformation are analyzed. For starved condition, film thickness at contact sides still remains fully flooded but decreases around contact center line because of the spring-back resilience of the material. Meanwhile, with increasing speed, the maximum deformation increases.