Fatigue Life Study Of 2.5 MW Wind Turbine Gearbox Bearing

With the increasing demand for energy from all over the world,wind energy as a kind of renewable clean energy has attracted widespread attention.The wind turbine industry has developed rapidly in the world.In some countries,wind power has even become the main energy source.Wind turbine gearbox is one of the core components of wind turbine.which has a low reliability,because it works in the field all the year round,and it suffered from the wind load which is random and alternating.According to statistics,the failure rates of gearbox is 9.8%,the ratio of downtime due to gearbox fault is as high as 19.4%.The ratio of bearing failure in the gearbox is 19%,which second only to gear.The paper takes the 2.5 MW wind turbine gearbox bearing as the research object,and researches fatigue life of bearing with condition of changing load,the results can provide reference for the reliability design of the gearbox.The concrete research content is as follows:The first chapter,summarizes the research background and significance,the development actuality of wind turbine at home and abroad,bearing reliability research actuality at home and abroad and the development actuality of wind turbine bearing.The second chapter,firstly researches the structural characteristics and transmission principle of gearbox,focuses on the Power distribution technology,and researches the failure mode and effect analysis(FMEA)of the gearbox,finally,further researches the failure mode and the reasons of the bearing.The third chapter,obtaining a more accurate continuous load spectrum through dealing with the collected 20-years' torque-revolution data.Secondly,the discrete load spectrum is fitted to Then,the force analysis of the gearbox is made.And then on this basis,the equivalent dynamic load spectrum of each bearing is obtained,which will lay the foundation for the next bearing life calculation.The fourth chapter,firstly introduces the concept of fatigue,fatigue life estimation method and Miner cumulative damage theory are introduced.Secondly,the Monte Carlo method is applied to the bearing damage calculation.Combined with the modified Miner cumulative damage theory to calculate the bearing under the 20-year load spectrum damage,and finally on this basis to calculate the bearing life.The fifth chapter,firstly the finite element simulation model of the gearbox is established by RomaxDesigner software.Secondly,the damage of each bearing under the 20-year load spectrum is calculated by software.Finally,the life of each bearing is calculated by Miner cumulative damage theory,and the results are compared with the theoretical calculation.The sixth chapter,summarizes the full paper and looks into the next step.