Wheel And Rail Wear Characteristics Of Linear Motor Metro Vehicles And Its Influence On Dynamic Performance

Compared with traditional rail transit vehicles,linear motor vehicles have the advantages of small radius curve passing,strong climbing ability,simple structure and low cost.Besides,the wheel-rail system of linear motor vehicles only plays a supporting role,and the wheel-rail wear is small,and linear motor vehicles have good development prospects.However,linear motor vehicles also have drawbacks of higher energy consumption than that of the traditional rotary motor,due to large air gap between the vehicle-mounted linear motor and the track induction plate.The air gap and electromagnetic force will fluctuate due to the vibration of the vehicle in operation,and the change of the electromagnetic force of the linear motor will also have an impact on the dynamic performance of the vehicle.There is once an instance that a domestic linear motor Metro line bears abnormal wheel-rail wear and vehicle shaking along with the increase of vehicle mileage.In this instance,there are several small radius curves on the line,and the speed of vehicles is high,the deterioration of dynamic performance of vehicles thus would not only lower the passenger’s ride comfort,but even affect the running safety of the vehicle.Therefore,it is very critical to study the dynamic performance of vehicles under wheel-rail wear and the safety issues when passing small radius curves.Vehicles running on this line are divided into two kinds – vehicles with inside axle boxes and vehicles with outside axle boxes.Firstly,static wear tests are carried out on wheels and main track of these two kinds of vehicles with different running mileage,and the development law of wheel-rail wear is analyzed.At the same time,vibration tests of these two kinds of vehicles running on the main line are carried out to substantiate dynamic model verification in the latter part of the paper.Contact geometry and contact stress of abrasive wheel-rail profile are calculated,and the wheel-rail matching state in running motion is analyzed.Based on their structural characteristics,dynamic models of the two kinds of vehicles are established,and joint simulation with electromagnetic force model is carried to compare the dynamic performance of the two kinds of vehicles.Finally,by using established dynamic models,measured abrasive wheel-rail profiles are input into dynamic model to explore the impact of wheel-rail wear on the dynamic performance of linear motor vehicles;safety analysis of the two kinds of vehicles when passing through the small radius curve in wheel-rail wear condition is undertaken.After above calculation and analysis,main conclusions are as follows:(1)Wheel wear of vehicle with outside axle boxes is greater than that of vehicle with inside axle boxes.Wheel polygon of two kinds of vehicles is mainly eccentric,wheel profile is mainly tread wear.The main wear of straight rail is the top wear.The rail gauge angle on the side of the curve high rail bears serious wear.(2)The stability and comfort of vehicle with outside axle boxes is better than that of vehicle with inside axle boxes when passing straight track,while vehicle with inside axle boxes outperforms in each dynamics index when passing curved track.(3)Wheel and track wear will reduce vehicle stability and curving performance.(4)To maintain the running quality,the suggested reprofiling period of vehicles is 70,000 km.The rail profile must be maintained to ensure the running quality of the vehicle.The vehicle speed can be reduced to 80 km/h to ensure the stability of the vehicle.