The Structure Reliability Analysis And Research Of Mw Scale Wind Generator's Main Shaft

The main shaft is one of the key transmission components for the wind turbine,with its front flange connected with hub by locking bolts and its rear connected with the input shaft of gearbox.In the working status,the main shaft not only needs to undertake the various loads from wind wheel,but also needs to transmit torque to the gearbox.The load acting on the main shaft is complicated and uncertain.According to the national standard of wind power industry,as a key component that can't be replaced,the structure design life of the main shaft should be more than 20 years and the structure reliability should be above 0.9999.In this paper,the FE model of the main shaft was established under ANSYS environment based on the analysis of its structure and boundary conditions.The static strength,stiffness and fatigue life of the main shaft were checked through the FE model established.At the same time,the structure reliability of main shaft was obtained by using the professional reliability analysis software.The reliability calculation was carried out by invoking the result of FEA.The main research contents of this paper can be summarized as follows:(1)The FE model was established for structure analysis based on the analysis of the main shaft structural parameters and constraints.At the same time,2 different constraint schemes were proposed,and the advantages and disadvantages of the 2 schemes were compared.Equivalent stress and deformation under the 16 ultimate load conditions were obtained by adopting the contact scheme with better calculation effect.(2)The fatigue life calculation of the main shaft was executed by the nCode design life model integrated in ANSYS workbench,which considered 46 groups of fatigue design conditions included in 5 categories.(3)In order that the randomness of the load parameters,the size parameters and the mechanical property parameters of the main shaft can been introduced into calculation,the FE model of the main shaft was established once again based on the parametric design language APDL of ANSYS.The static strength reliability of the main shaft and the reliability index sensitivity of the random parameters was obtained by using the professional reliability analysis software NESSUS.The reliability calculation was carried out by calling the result file of ANSYS.(4)The DOE experiment design for the main shaft was carried out by using the data optimization software ISIGHT.In the course of experiment,the FEA result would be invoked in succession.The 5 dimension parameters which have greater influence on the working stress of the main shaft were found out.A two order approximation model for this five parameters and the maxium equivalent stress was built through the experiment data.The optimization design was performed in order to find the minimum volume under the condition of ensuring reliability.