Preliminary Study On Mechanism Of Wheel Polygon Of Type A Metro Vehicle

With the rapid development of metro in China,the phenomenon of wheel polygonal wear has become increasingly significant.Wheel polygon can increase the wheel/rail interaction force,cause violent vibration of vehicle and rail components,reduce service life,increase noise inside the cabin,affect riding comfort,and even threaten operating safety.Scholars have carried out many studies on wheel polygon,but there is still no consensus on the mechanism.This problem is one of the problems that need to be solved urgently in the wheel-rail system.Aiming at the problem of wheel polygon of a domestic type A metro vehicle,this thesis conducts preliminary research on the mechanism of the wheel polygon through field investigation and computer simulation.The main work and conclusions of this thesis are listed as follows:(1)First,a literature review on wheel polygon is presented,in which the significance of research on the mechanism of wheel polygon are emphasized.(2)A wheelset three-dimensional finite element model is established using ANSYS,and its modal analysis and substructure analysis are carried out.The wheelset finite element model is imported into the multi-body dynamics software SIMPACK by the interface between SIMPACK and ANSYS,so that a vehicle system dynamic model considering the wheelset flexibility is established.(3)Combining with the investigation of the wheel polygonal wear,wheelset modal analysis,vehicle vibration test and the wheel/rail contact force simulation,the reasons for the wheel polygonal wear is analyzed.The results show that the circumferential uneven wear characteristics of the wheel are mainly eccentric,and 11~16 order polygons.The high-order polygons(11 ~ 16)have a side length of 163 ~ 237 mm.the first-order bending resonance of the wheelset is the main reason for the wheel polygonal wear.The extensive use of floating slab and ladder sleeper track is the environmental incentive.(4)Investigation or simulation is conducted to study the influence of axle stiffness,rail corrugation,wheel re-profile and brake shoe on wheel polygonal wear,and the mitigation measures for metro wheel polygonal wear are proposed.The results show that the wheel first-order bending resonance hardly be excited by improving the axle stiffness and rail grinding.It can significantly improve re-profiling using wheelset center fixing method and increasing the number of feeds during re-profiling,to eliminate the polygonal wear.Improving the matching degree between the brake shoe and the wheel tread can suppress the formation and development of wheel polygonal wear.(5)The re-profiling limits of wheels with 10~20 orders polygon are studied by simulation using the vehicle system dynamic model considering the wheelset flexibility.The wheels with polygon orders of 10~13,14~16,and 17~20 are classified into three categories,and the corresponding safety limits are 0.3 mm,0.2 mm and 0.1 mm,respectively.