Primary Hunting Behaviour And Suppression Methods Of Vehicle Systems

The development of society and economy has put forward higher requirements for the running speed of the train.With the continuous increase of the running speed of the train,the problems of vehicle system dynamics have been arised,especially those caused by the vehicle hunting movement.The hunting motion is a special phenomenon caused by the wheel/rail geometric relation and creep forces,and is the inherent attribute of railway vehicle system,which is one of the core issues of vehicle system dynamics.There are two typical forms of hunting motions in vehicle systems,i.e.,primary and secondary hunting motions.The one that the car body has relatively large harmonic vibration while the bogie vibration relatively small,and which appears normally at small wheel/rail contact equivalent conicity or at lower speed,is called primary hunting motion(or carbody hunting).Primary hunting not only causes vehicle sway,but also affects the ride quality of the vehicle,worsens the comfort of passengers.Thus,the work of the thesis is mainly focused on the issues of primary hunting motion.The vehicle hunting motion is affected by many factors,such as equivalent conicity,vehicle speed,suspension parameters,etc..But at present,the study on how to suppress the primary hunting efficiently is still not systematic and enough.Therefore,the carbody hunting mechanism and effective restraining measures need to be studied intensively.In order to investigate the influence of various factors and their coupling on the carbody hunting,so as to specifically suppress the carbody hunting motion and improve the stability of the vehicle,this thesis uses the SIMPACK software to set up the nonlinear dynamic model and simulates the carbody hunting instability.And the tracking test verification is conducted to grasp the carbody hunting instability mechanism.Furthermore,the impact of the primary suspension stiffness,anti-hunting damper and inter-carbody damper,and the secondary lateral damper semi-active control law are extensively investigated,and corresponding improvement measures are proposed,so as to achieve the purpose of effectively suppressing the carbody hunting motion and improving the vehicle stability.