Study Of Wheel/Rail Dynamic Behavior Considering Wheelset Structural Flexibility

In conventional railway vehicle system dynamics models, components of the vehicle are modeled as rigid bodies and the available frequency range of these models is below20Hz. With the development of high speed and heavy haul railways and the lightweight design, the effect of the structural flexibility of vehicle and track on the vehicle system dynamic performance cannot be neglected. In order to study the abnormal wear and fatigue failure of vehicle and track components as well as wheel-rail vibration and noise, a high frequency domain should be considered in the vehicle system dynamics model. The wheelset structural flexibility, which is one of the most important parts in the high frequency vehicle system dynamics model, affects not only the vehicle dynamic performance but also the creep, wear and noise of wheel and rail. Taking a metro vehicle as a research object, the work of this thesis is introduced as follows.First wheel polygonal wear of the metro vehicle is measured on site. Based on the measure results, the characters of wheel polygonalization and its formation mechanism are analyzed. It is found that the first wheelset bending resonance is the crucial factor causing the wheel polygonal wear. The wheel polygonalization caused by the first wheelset bending resonance is suppressed through increasing the diameter of the wheelset axle.The finite element model of metro wheelset is established and applied to carry out the modal analysis. Using the above finite element model of wheelset as a submodel, the metro vehicle system dynamics model considering the wheelset structural flexibility is developed by using the multi-body system dynamics simulation software SIMPACK. In the model a massless rigid wheel tread is fixed on one point of the elastic wheelset, which helps transmit the force and kinematic behavior. The difference between the vehicle dynamics model with rigid wheelset and flexible wheelset is presented. The necessity of considering wheelset flexibility is confirmed. The results show that the wheelset structural flexibility has an effect on the wheel-rail dynamic performance, especially vertical vibration. To thicken the axle diameter can decrease the vertical vibration and then improve the wheel-rail dynamic interaction. Under the random excitation, the first bending resonance of wheelset is easily excited, which further explains the formation mechanism of metro wheel polygonal wear.