Contact Analysis And Optimal Design Of Main Bearing Of Wind Turbine

Wind power, as a kind of clean energy, has received the widespread attention around the world with the consumption of fossil energy. Wind power technology has also achieved rapid development. The main bearing is the core component of the wind turbines. The quality of the main bearing directly determines the performance of the wind turbines. Now the researches on the wind power bearing are mainly concentrated on yaw and pitch bearing, or the double-row spherical roller bearing and four-point angular-contact ball bearing, rarely involve double-row tapered roller bearing. With the power of wind turbines increases, more and more companies set double-row tapered roller bearing as the main bearing for 3 MW direct drive wind turbines. Therefore, it’s necessary to do research on the double-row tapered roller bearing of the wind turbines, and the achievements can provide technical guidance for the design and manufacturing for the enterprise.Taking the double-row tapered roller bearing of the 3 MW direct drive wind turbines as the research object, an analysis model is proposed. The internal contact load and pressure distribution are obtained under extreme load and equivalent load. We obtain the fatigue life of the bearing based on the L-P fatigue theory and the relationships between the axial clearance and the bearing’s fatigue life. The profile design of the tapered roller is conducted under extreme load condition. A static analysis of the bearing is also done with Workbench software. Based on ISIGHT optimization software, the optimization design of the main bearing is completed by using the multi-island genetic algorithm. The specific studies are as follows:(1) Firstly, a basic knowledge of the common arrangement types of the main bearing system and the types of the main bearing are introduced. This paper also elaborates the main structural parameters of double-row tapered roller bearing, linear elastic contact theory of Hertz, the position and motion of rigid body and the knowledge of coordinate transformation.(2) A five-degree of freedom quasi-static analysis model is proposed based on coordinate vector operations. The proposed model is compared with the existing models, which proves the accuracy and the advantages of the model.(3) The model is applied to the 3 MW wind turbines and the static safety factor of the main bearing is checked. The contact force and contact pressure distribution of the bearing is obtained under extreme load and equivalent load. The influence of titling moments on the bearing’s internal load distribution is also studied. We obtain the fatigue life of the bearing based on the L-P fatigue theory and the relationships between the axial clearance and the bearing’s fatigue life under equivalent load. The logarithmic curve profile design of the tapered roller is conducted under extreme load and a static analysis of the main bearing is also done with ANSYS/Workbench software.(4) The optimization design of the main bearing is completed based on ISIGHT software. The design of experiments is conducted to test design parameters’ influence degree on the objective function and the model of main bearing’s fatigue life is solved based on the multi-island GA method. The fatigue life of the main bearing has increased by 79.36 percent after the optimization.