Bending Fatigue Life Simulation Analysis Of Helical Gear Pair Of High-speed EMU Gearbox

As an important working part of high-speed train transmission system,the gear pair plays an indispensable role during the safe and reliable working of high-speed train.During the working of high-speed train,acceleration,deceleration,emergency braking and other complex conditions occur constantly,and these devastating complex conditions will greatly reduce the gear life.And once the gear has fatigue fracture,it will directly affect the safe operation of the train,thereby endangering the safety of passenger's life and property.According to some date,The gear failure is about 60% of the high speed gearbox failure.There are two main types of gear failure,the largest proportion of which is fatigue broken of teeth,the proportion of surface contact fatigue followed.Therefore it is necessary to study the fatigue life of the helical gear of the high-speed EMU gearbox.In this paper,based on the theory of gear meshing theory,fatigue theory and fracture mechanics theory,the finite element method is used to simulate the bending fatigue life of high-speed rail gear.This article conducted research on CRH380 A EMU gearbox output gear.The main contents are as follows:Firstly,based on the involute equation and the tooth root transition curve equation in the processing coordinate system,the 3D model of high speed train gear pair was built in UG software.In order to verify that the gear model was valid and reasonable,the motion simulation of the helical gear pair was carried out by using assembly and motion simulation module.Secondly,the three-dimensional model of test gear and fixture was established in UG software.Then,the assembly model was introduced into ABAQUS to calculate the stress-strain of the test gear in the static module under constant load.The finite element results of the test gear was introduced into the FE-SAFE software.The fatigue life of the test gear was calculated by the nominal stress method and the local stress-strain method respectively.The bending fatigue test of the test gear was carried out.By comparing the two finite element results with the experimental result,the optimal damage model of gear bending fatigue was determined.Thirdly,the three-dimensional model of helical gear was introduced into ABAQUS,and the stress-strain of helical gear under static load was calculated by using ABAQUS static module.In the FE-SAFE software,the bending fatigue life of the helical gear pair was calculated by using the optimal damage model.Furthermore,it was researched that the influence of load magnitude,residual stress,tooth surface roughness and profile modification on fatigue life of helical gear.Fourthly,the three-dimensional model of the helical gear with a semioval initial crack was introduced into ABAQUS to calculate stress intensity factors of tooth root crack front.And then by changing the load magnitude,the crack size and the crack shape,the variation law of the stress intensity factor of the initial crack of the tooth root was obtained.Finally,the growth trajectory of crack in tooth root was simulated by using the crack propagation function of ABAQUS software XFEM module.The propagation life of the tooth root crack was estimated by the Paris formula,and then the influence of load magnitude,crack size,crack shape and shape modification on crack propagation life was researched.The research work of this paper can provide theoretical support for the design and maintenance of gear,and further improve the safe and stable operation of high-speed EMU.