A life test method and result analysis for slewing bearings in wind turbines

Slewing bearings generally consist of the rotational connection between two substructures and are usually used for complex load at very low speeds. If the slewing bearing has some faults during the working lifecycle, the machine will have to be stopped and the slewing bearing will be disassembled for checking the internal surface damage of the rings or rolling elements to prevent serious accidents. However, this is a very difficult process and will cost a lot of manpower, time, and money. Although there is a large number of traditional or modern techniques used widely in general bearings, they may not be able to predict the remaining service life of slewing bearings precisely due to the huge difference between the general bearings and the slewing bearings, thus, the experiments are the most effective and reliable methods. In this paper, a special test table for slewing bearings applied in wind turbine generators is presented and an accelerating fatigue life test method based on the test equipment is proposed to study the fatigue properties and predict the remaining service life of the slewing bearings used in wind turbines. It is shown that the presented test equipment can realistically reflect the state of slewing bearings under the actual working conditions. What’s more, the experimental results show that the proposed method is conservative and provides a more accurate prediction of the fatigue life for the slewing bearings and also can meet the high reliability requirements of the slewing bearings in wind turbines.