Dynamics Performance And Wheel/Rail Wear Of Linear Induction Motor Vehicles With Two Kinds Of Axle Box Positions

The linear induction motor(LIM) metro system is a new type of urban rail transit. In terms of axle box position relative to the wheelset, LIM metro vehicles are sorted to inside axle boxes and outside axle boxes. The LIM vehicles with inside axle boxes and outside boxes have been running on some domestic metro lines. Through field tests, different wear features and laws were found on the wheels of the vehicles with the two axle box suspending structures. And the intensive vibration caused by wheel/rail wear leads to frequent fatigue damage of vehicle and rail components. By using the models of the two structured vehicles running on the metro line, the wheel/rail wear and dynamics performance are compared in the paper. These models and the simulation results provide theoretical basis for the improvement of LIM metro vehicle and the design of new products. The main research works are as follows:1. The wheel/rail wear of the two structured LIM vehicles running on some demestic metro lines were measured periodically, which includes wheels’polygon wear, wheel tread’s lateral wear and rail corrugation. And the wear features of the two structured vehicles were compared.2. Based on vehicle/track coupling dynamics theory, the LIM metro vehicle/slab track coupling dynamic model is developed. In the model, the vehicle is simplified as a multi-rigid-body system of35degrees of freedom (DOF), in which the structures are connected by the spring-dampers. Each rigid-body has5DOFs, including lateral, vertical, roll, pitch and yaw. A Timoshenko beam is used to model the couple of rails which are discretely supported by sleepers. The slab is simplified as the three-dimension solid FE (finite element) model. The rail model and track model are both computed by the mode superposition method. The running behavior of the vehicle is realized by moving supporters under the rails in the opposite direction. The vertical electromagnetic force between the LIM (stator) and RP (rotor) is assumed as a non-linear function of air gap and the lateral restoring force is1kN A Euler beam is used to model the LIM and RP. The LIM is suspended at the midpoint of the front and rear wheelsets through two spring-damper elements. The RP is fastened to the slab with spring-damper elements. The Hertzian contact theory and the Shen-Hedrick-Elkins’model are adopted to deal with, respectively, the normal dynamic forces and the tangential forces between the wheels and the rails. With the developed model, the moving stability, riding comfort and curving performance of the inside axle boxes and outside axle boxes LIM vehicles are compared. The simulating results could explain the measured data of wheels’wear.3. The periodically measured wheel’s polygon wear, wheel tread’s latteral wear and the rail corrugation, were put into the LIM metro vehicle/track model to compare the wheel/rail wear’s impact on the dynamic performance of the two structured vehicles. 4. Based on the developed dynamic model, the influences of longitudinal stiffness of primary suspension, lateral stiffness of primary suspension and the lateral distance between the left and right primary suspensions on vehicle dynamic performance were investigated and the parameters were optimized.