Research On Lightweight Design Method Of Key Components Of Wind Turbine

With the development of wind power industry in China,small capacity of wind turbines have been unable to meet the market demand,and large capacity ones are becoming more and more popular.The increase of single capacity of wind turbine will lead to the increase of volume and mass of it.The main shaft and hub,the key parts of the wind turbine,are beared to various loads during operation.Therefore,the strength analysis of them is directly related to the safety of the wind turbine’s operation,and the lightweight design is beneficial to reducing the overall quality,manufacturing cost,and transportation difficulty of it.In this paper,the statics of main shaft and hub were analyzed,and the lightweight design method of them were researched,and the fatigue strength were checked.(1)The blade load was calculated according to the blade element-momentum theory,and the limit load of the main shaft and hub was obtained by transforming the load into the coordinate system specified by GL.The parametric model was established by using 3D modeling software,and the model was simplified appropriately,and introduced the related methods of wind turbine lightweight design,which laid a solid foundation for the strength analysis and lightweight design of the main shaft and hub.(2)During the lightweight design of the main shaft,Firstly,the statics results of the main shaft under 16 extreme load conditions are calculated.Through the comparison of results,the maximum limit load of the stress and deformation of the main shaft was obtained,and a mathematical model of main shaft lightweight design was established.Then the method of Design of Experiment(DOE)was used to obtain the initial sample points,and the Kriging model was used to establish the response surface,obtain influence degree and variation trend of each design variable on stress,deformation and quality,at the same time,get the local optimal solution.Finally,the Multi Objective Genetic Algorithm(MOGA)was used for optimization,and the global optimal solution was obtained.Under the condition of ensuring the strength,the weight of the main shaft was reduced by 10.71%.(3)During the lightweight design of the hub.Firstly,the static results of hub were calculated under the limit load condition.Fristly,the lightweight design method based on Kriging model and MOGA algorithm was adopted,and the hub weight was reduced by 10.46%.Then,topology optimization of the hub was carried out,According to the static results and structural characteristics of the hub,the appropriate optimization regions and non optimizations region and optimization ratio were selected to obtain the topology optimization results.The hub structure was redesigned by drilling,and finally the weight of the hub was reduced by 5.439%.Finally,through comparison,it can be seen that the weight reduction effect of the lightweight method based on Kriging model and MOGA algorithm is obviously better than that of the topology optimization method.(4)The mainshaft and hub bear various alternating loads during work,which is easy to cause fatigue damage.So,it is necessary to analyze the fatigue of them.Firstly,the stress of main shaft and hub under unit load was calculated.Then the fatigue load spectrum was obtained by rain flow counting method,and S-N curves of them were obtained by calculation.Finally,Miner law was used to evaluate the fatigue damage of the lightweight main shaft and hub,the results showed that them without fatigue failure in the working cycle.