Study On Mechanical Properties And Fatigue Life Of Double Row Tapered Roller Bearing For Large Wind Power

Wind energy regarded as one of the most competitive and promising renewable clean energy,has great application prospects and puts forward higher requirements and challenges for wind power equipment.As the key component of the wind power equipment,double row tapered roller bearings are widely used in the main bearing of semi direct drive and direct drive fan,and its performance have an effect on the safe use and the service life of the whole machine.At present,the domestic research on double row tapered roller bearing is still in the preliminary stage.Due to the double row tapered roller bearing with the feather of complex structure,large size and variable service load,the conventional bearing design theory cannot meet the design requirements of the large bearing.In addition,there are still many key problems for its fatigue life evaluation and prediction.In this paper,the research on the contact mechanics behavior,the multi body coupling modeling and the fatigue life of double row tapered roller main bearing in the 3.4mw wind turbine is carried out.The main contents are as follows:1)The mechanical model and static balance equation of the double row tapered roller bearing are established for analyzing the change law of contact load.The influence of roller number and overturning moment on bearing contact load is discussed.Based on the finite length contact theory,the roller contact stress distribution is calculated,and the stress change of the tilted roller end is researched.2)The rigid flexible hybrid multi-body mechanical finite element model of wind turbine hub,wind turbine locking plate,wind turbine locking flange,main bearing,gearbox,generator shell and engine room elbow is established.The rigid flexible hybrid multi-body contact mechanics research is completed,and the contact load and stress distribution are obtained.The single bearing finite element model is established to analyze the static strength.Based on it,the local structure sub model is built for the maximum contact load position.3)The fatigue life of the bearing is calculated by the L-P theory and the ISO theory.The fatigue life prediction based on finite element method is studied by n Code software.The optimum roller convex type is obtained by analyzing the contact stress and the bearing life of the three common roller convex types in engineering.According to the contact mechanics,the roller structure design is further carried out.The relationship between the hollowness of different types of hollow rollers and life change is discussed.The influence of deep hole depth on bearing life is carried out for equal proportion tapered roller with hollow degree of 50%.4)The local sub model structure was manufactured.The contact stress test was carried out based on the induction paper method.The contact stress is calculated by taking the measured contact width into the formula,and the validity of the simulation model was verified.The S-N curve of the 42 Cr Mo bearing material was obtained by the fatigue test,which provided basic data for theoretical research.