Hunting stability and dynamic stress analysis of a high-speed bogie using elastic-suspended motors as dynamic vibration absorber

The traction motors installed on the bogie frame of high-speed trains are of adverse effect on the bogie hunting stability. Utilising the elastic-suspended motors as dynamic vibration absorbers can increase the hunting critical speed. However, the vibration and dynamic stress of the motor system will be aggravated compared to the rigid motor suspension. In this work, the hunting stability and dynamic stress of a high-speed bogie with elastic-suspended motors are studied. Firstly, the DVA mechanism of hunting stability for a bogie with elastic-suspended motors is conducted by the eigenvalue method. Increasing the critical speed by the elastic motor suspension will sacrifice the motor vibrations and stresses. Secondly, the rigid-flexible coupled dynamic model of the vehicle and motor system is developed to give insight into the consequent effects on dynamic stress. Finally, some countermeasures, e.g. wheel-rail conicity control and motor suspension optimisation, are proposed to suppress the dynamic stress of the motor hanger system. One effective manner to suppress the dynamic stress of the motor hanger system is to improve the hunting stability by limiting the wheel-rail conicity. Another one is to lower the lateral stiffness of the motor suspension and increase the damping ratio of the motor damper.