Fatigue analysis of large stewing bearing using strain-life approach

摘要

Large slewing bearings are designed to sustain axial, radial and tilting moments. Due to their design and manufacturing process, a nonstandard approach has to be used to calculate the fatigue life. First, a maximum contact force is obtained from the load distribution in a bearing by means of analytical expressions of the Hertzian contact theory. Then, a strain-life approach is used to calculate the fatigue life on the basis of the subsurface stresses as obtained from the finite element analysis. Experimentally determined depth-dependent elasto-plastic material properties, which appear as a result of hardening, are taken into consideration. The fatigue life largely depends on external bearing loads. For an external loading, which results in 3200 MPa contact pressure on a bearing raceway, the fatigue life is approximately 4.69e7 load cycles (1.54e6 revolutions). The calculated fatigue life is in accordance with the requirements of the fatigue life of wind turbines' blade flange bearings.