Study On Mechanical Properties And Fatigue Life Of Four–Point Contact Ball Bearings Used In Wind Turbines

Four–point contact ball bearing is the core component of wind turbine and the blade aerodynamic load can be transferred to the hub through four–point contact ball bearing, so the reliability of it will directly decide whether the wind-power generator can be operating smoothly. Based on the intensity analysis and fatigue analysis theory, the simplified finite element model and sub model of the variable four–point contact ball bearing are presented and the mechanical properties and fatigue life of large double row four point contact ball bearings are studied by the simplified model and sub model. Finally, the four–point contact ball bearing structure parameters were optimized with genetic algorithm and finite element theory. The research methods have provided basis for the design, checking and optimization of four–point contact ball bearing of wind turbine, which has a certain practical value. The main research contents of this paper are as follows:(1) The theoretical research on large double row four point contact ball bearing. A bearing mechanics analysis model was established. And the structure features of the bearing and load were studied by this model. Based on research on the bearing fatigue analysis theory, the fatigue life calculation method of this bearing was provided.(2) The studying on the finite element modeling of four–point contact ball bearing with bolts. The contact characteristics between raceways and rolling elements and load situations of the bolts were studied. The equivalent contact stiffness model of ball and bolt were set up respectively, and a new large double row four point contact ball bearing finite element simulation method was proposed based on this model. The finite element model is established respectively according to the new method and the conventional simulation method. By comparing with theoretical and experimental results, new simulation method was more suitable for four–point contact ball bearing simulation analysis.(3) Research on the influence of bolt pretension on the bearing load distribution. To study the influence of bolt pretension to variable four–point contact ball bearings mechanical properties, a four–point contact ball bearings finite element model with the different bolt pretension is established, which provides practical references for engineering.(4) Study on fatigue life of large double row four point contact ball bearing. First, a ball elastic contact sub model is established. Then the influence of the bearing raceway surface hardness and bolt pretension on bearing service life is studied with the method of stress life.(5) Research on Four–point contact ball bearing structural parameters optimization design. According to the genetic algorithm and finite element theory, the parameters optimization of four–point contact ball bearing structure is completed. The results suggest that the mechanical properties and fatigue life of the ball bearing have significant improvement...