Study On Dynamic Response Of Electric Locomotive Under Wheel Polygonal Wear Excitation

With the increase of running speed and axle load of electric locomotives in China,the problem of wheel polygonal wear is becoming more and more serious.The wheel polygonal wear will cause the violent vibration of locomotive and vehicle,increase the environmental noise,and adversely affect the running quality of locomotive and vehicle.In serious cases,it will lead to fatigue fracture of locomotive and vehicle parts and endanger the safety of opreation.Therefore,the problem of wheel polygon has attracted the attention of many scholars both here and abroad.In particular,the study of vehicle/track dynamic behavior under wheel polygonal wear excitation has important theoretical significance and great engineering application value.Aiming at the abnormal phenomena of wheel polygonal wear of a HXD locomotive,this thesis studied the dynamic response of electric locomotive under the excitation of wheel polygonal wear by means of field test and simulation analysis.The main work and conclusions of this thesis are listed as follows:(1)The studies on vehicle/track dynamic behavior under wheel polygonal wear excitation in the past and current in the world are reviewed.The significance and orientation of research on dynamic response of electric locomotive under wheel polygonal wear excitation are clarified.(2)The problem of locomotive wheel polygonal wear was investigated systematically,and the vibration test of locomotive was conducted in the railway field.Through the wheel polygon test,the basic characteristics and distribution regularities of wheel polygonal wear of this locomotive are mastered.Through the vibration test,the vibration characteristics of the locomotive are mastered,and the fundamental causes of abnormal vibration of locomotive are revealed.(3)Based on the multi-body dynamics software SIMPACK,a rigid-flexible coupling dynamic model of locomotive-track system is established,considering the elastic deformation of rail,wheelset and frame.The model is validated with the locomotive vibration test results.By comparing the simulation results of rigid body model and rigid-flexible coupling model with the experimental results,the influence of elastic deformation of key components on vehicle/track system dynamics is briefly analyzed.It is found that the rigid-flexible coupling model is more accurate and reliable.(4)The dynamic response of wheel-rail system under the excitation of wheel polygonal wear is studied by using the simulation model,and the locomotive wheel polygon re-profiling limit is put forward.The results show that the wheel-rail vertical force increases linearly with the wave depth.When the polygon excitation frequency is close to the frequency of motor heaving motion or the first-order vertical bending modal,it will cause greater vertical force fluctuation.The change of wheel-rail vertical force is ahead of the non-circular amplitude of wheel,namely the maximum of wheel-rail vertical force occurs when the radius of wheel instantaneous rolling circle increases;Wear index reaches a maximum at the trough of wheel polygon.With the increase of locomotive traction mass,the development of wheel polygonal wear will be accelerated.For the wheels with polygonal wear of 15-25 orders,the recommended re-profiling limit value is 0.15 mm.(5)The vibration response of locomotive system under the excitation of wheel polygonal wear is studied by using the simulation model,and the control measures of abnormal vibration of locomotive are put forward.The results show that the vibration of locomotive axle box and frame will be aggravated by the increase of wave depth,order and speed under the excitation of harmonic wear.Under the typical measured polygon wear excitation,the vibration of axle box is greatly affected by polygon excitation,while the vibration magnitude of frame is related to polygon wear excitation,sleeper parameter excitation and P2 resonance;Aiming at the abnormal vibration phenomenon of locomotive caused by high-order polygon,this paper puts forward the abnormal vibration control measures from the standpoint of wheel re-profiling,changing locomotive running speed and optimizing primary suspension parameters.