Analysis Of Stress Intensity Factor And Fatigue Life Of Wind Turbine Gear Crack

Wind power has become one of the world’s most important green new energy industries,the speed increase gears in the wind turbine speed increase gear box is the main transmission components of the wind turbine.The failure of the speed increase gear can lead to significant property damage and safety accidents,its main form of failure is fatigue fracture,of which the crack caused by the fatigue fracture of the gear is the most important cause.This paper takes a 1.5MW series wind turbine speed increaser gear as the research object,and analyzes the initial cracked gear stress intensity factor and crack expansion characteristics and remaining life analysis for the cracked wind turbine gear fatigue fracture problem,mainly including the following.Firstly,by theoretically analyzing the stress intensity factor calculation method,the basic equation of gear crack stress intensity factor is established to provide the theoretical basis for the later investigation of the initial crack stress intensity factor and crack expansion finite element analysis of spur gear and helical gear tooth rootSecondly,this article aims at the problem of fatigue crack fracture of the speedincreasing gear in a 1.5MW series wind turbine to explore its gear crack propagation characteristics.Since the speed-increasing gears of this series of wind turbines have both spur and helical gears,it is necessary to establish three-dimensional models and finite element models of the speed-increasing gears of two wind turbines,spur gears and helical gears,and perform the force analysis when the gears are meshed.In order to determine the most prone position of three-dimensional cracks,it provides a basis for the creation of subsequent cracks.Again,using finite element method combined with fracture mechanics theory,the numerical curve distribution law of three-dimensional crack stress intensity factor and J integral at the tooth roots of spur gears and helical gears under different initial crack parameters are investigated.The changes of three kinds of stress intensity factors and J integral under different crack lengths,different crack positions and different load conditions are analyzed.Research shows that when the data of different initial crack parameters are changed,the corresponding curves of the three stress intensity factors and the J-integral have obvious changes.Finally,the interaction integral method is used to study the variation of the initial single crack at the edge of the tooth root and the double crack at the middle of the tooth root.Based on the fracture mechanics principle combined with the finite element principle analysis and calculation,the change pattern of stress intensity factor and the number of fatigue extension cycles is derived.The effect of changing the position of the single crack at the root edge on the fatigue expansion life of the three-dimensional crack at the root edge is analyzed.A gear crack containing only one crack is created as the original initial crack model,and the stress intensity factor and fatigue expansion life of the crack expansion are calculated.A second crack is created on the original initial single crack model,and the change of stress intensity factor and fatigue expansion life of the original initial crack and the original initial crack leading edge of the single crack in the double crack are investigated by changing the initial position of the second crack.