Research on performance analysis methods of pitch bearings based on nonlinear springs

ObjectiveIn engineering applications, pitch bearings contain hundreds of pairs of nonlinear contact between rolling elements and raceways, the force condition is complicated, and the complete solid model analysis is difficult. In order to accurately describe the motion, force characteristics of pitch bearings and the stress distribution law of the rolling body, the equivalent mode between the rolling body and the raceway was studied.MethodsThree-row cylindrical roller bearings of 5 MW wind turbines were taken as the research object. Firstly, the integral physical calculation model of root-bearing-hub considering the bolt connection was established, the stiffness of nonlinear spring combination element was calculated by the Hertzian contact theory to simulate the deformation of rolling body, and the contact mechanical relation between the rolling body and the raceway was established. Secondly, the equivalent bolt and the friction contact of the joint surface were included in the actual calculation, and the structural performance of the bearing was analyzed and studied. Finally, the physical calculation model was used to analyze the bearing capacity of the pitch bearing.ResultsThe results show that the error is less than 5% by comparing the value of the maximum contact load of the bearing with the theoretical value calculated by the empirical formula of the National Renewable Energy Laboratory (NREL). The method has some practical engineering value and provides reference and basis for the rational design and manufacture of the pitch bearing of wind turbines.