Study On Vibration Characteristics And Fatigue Strength Of High-speed Train Gearbox Considering Out-of-round Wheel

Gearbox housing is a key component transmitting torque.With the increase of the operating speed of vehicle,external excitation increases in the same time,and the operating environment becomes worse,which brings more challenges to dynamic performance and fatigue strength of gearbox structure.Recent years,faults represented by cracking of gearbox housing happen frequently,and their fault feature reflects potential relation with wheel out-of-roundness,which inspires scholars to cogitate on the relation between these two phenomenons.Thus,demonstration and intensive research need to be carried out urgently.Meanwhile,under the advanced requirement of high-speed train development,operation and maintenance problems of gearbox ask for theoretical support and suggestion of relevant research eagerly.Under this background,considering out-of-round wheel conditions,relevant research to vibration characteristics and fatigue strength of gearbox has important practical significance.Based on this point of view,this paper set gearbox dynamic system containing gear transmission system and gearbox housing as study object,the main contents are as follow:Firstly,based on the relevant parameters of a certain type high-speed EMU,rigid-flexible coupling dynamic model including improved bending-torsion-shaft-swing gear transmission system model and finite element model of gearbox housing is established through the combination of SIMPACK and ANSYS.Secondly,analysis to the statistical law of wheel polygonization is carried out,the settings of wheel polygonization and wheel flat conditions in simulation are analyzed and determined.Polygonal wheel and flat wheel are set up by harmonic function method and radius deviation method,respectively.Thirdly,through setting normal operating condition,wheel polygonization condition and wheel flat condition in rigid-flexible coupling vehicle dynamic model,dynamic parameters,such as transmission error and stiffness,are analyzed.Contact strength of gear meshing is checked.Corresponding conclusions are obtained.Then,modal analysis to gearbox housing is applied.ANSYS and SIMPACK are used for co-simulation.Combined with line test and bench test,vibration characteristics and dynamic stress of gearbox housing are analyzed,the relation between resonance of gearbox housing and wheel out-of-roundness is intensively studied.Strength analysis to gearbox housing is carried out,and dangerous point is confirmed,furthermore,strength checking is applied.Comparison of dynamics and strength to different gearbox housing is conducted.A series of conclusions are drawn.Finally,based on fatigue life analysis theory,starting from dynamic simulation results,counting and analysis to load spectrum are conducted.Then,combined with S-N curve of the gearbox housing material,lifetime of gearbox housing on different conditions are calculated.Fitting to fatigue life curve is carried out by least square method.A one-step prediction model from wheel out-of-roundness to predicted lifetime of gearbox housing is proposed,which provides reference and suggestion for operation and maintenance decision of high-speed train gearbox components.