Structural Strength And Fatigue Life Analysis Of Casting Main Shaft Of Wind Turbine

The main shaft of the wind turbine is subjected to a variety of complex loads from the wind wheel hub during operation.It is one of the key components in the transmission system.The rationality of its structural design will directly affect the performance of the transmission system and the entire wind turbine.According to the requirements of the wind power industry,the main shaft of the wind turbine must have a design life of more than 20 years.In addition,the main shaft has a large weight and is mostly produced by forging,and the production cost is relatively high.It can be changed to casting production with obvious advantages in reducing weight and cost.Therefore,on the premise of meeting the structural strength and fatigue life requirements,the lightweight design of the casting main shaft can be realized,which can reduce the manufacturing cost effectively.In this thesis,the casting main shaft of 3MW wind turbine is selected as the research object.Using the finite element method,this article research on multi-body modeling,numerical simulation and optimization design.The research results are of great significance to the independent research and engineering application of the structural design of key components of wind turbines.The main research work is as follows:1.Based on the assembly model of the wind turbine main shaft system,a finite element model of the main shaft system was established.The loads are applied at the center of the hub.In order to simulate the support effect of the bearing on the main shaft,the LINK10 unit is used instead of the bearing roller.Through the nonlinear contact analysis,the static characteristics of the main shaft under 16 extreme conditions was studied.The results show that under the DLC1.3-a1 working condition,the working stress of the main shaft reaches the maximum value of 175 MPa,which meets the structural strength requirements.2.Based on the Miner criterion,this article researched on the materials and load history of the casting main shaft used for fatigue life analysis.The rain flow counting method was used to simplify the fatigue load spectrum and check the fatigue strength of the main shaft under different surface roughness conditions.The results show that the main shaft with a surface roughness of less than 200 ?m meets the fatigue strength requirements.3.According to the vibration theory of the main shaft,this thesis analyzed and compared the natural frequencies and vibration modes of the single shaft,the main shaft with bearings and the transmission chain under unconstrained conditions.Furthermore,the prestressed modal analysis is carried out on the constrained transmission chain model.The results show that the main shaft will not resonate with the wind wheel.4.According to the results of structural strength and modal analysis,a combination of topology,shape,and size parameter optimization was used to achieve the goal of 17.22% weight reduction of the casting main shaft while meeting the strength and fatigue life requirements.This method makes the production materials more fully utilized and provides a basis for reducing production costs and further optimizing the design.