Research On Polygon Wheels Wear Of High Speed Train By Simulation

In the actual operation of high-speed trains,it is found that with the increase of train running speed and running mileage,the wheel gradually showed a polygonal phenomenon under the action of various induction and force.Wheel polygonalization will lead to a sharp increase in wheel-rail force,aggravate vehicle vibration,destroy track and train components,and affect the stability and safety of train operation.At the same time,as the wheel polygonization depth deepens,the vibration noise of the vehicle will also increase.Firstly,this paper summarizes the current research results on the theory of wheel polygon formation.Then the testing and recognition methods of wheel polygon are described,and the advantages and disadvantages of direct and indirect measurement are summarized.Finally,the maintenance and evaluation criteria of wheel polygon adopted in our country at present are described in detail.In order to study the influence of wheel polygonization on vehicle dynamic performance,the dynamic model of a certain type of EMU is established.The effects of harmonic order,wave depth and phase difference of wheel polygon on dynamic performance are studied and calculated.The wave depth limits of wheel polygons under different harmonic orders are analyzed.Finally,the variation trend of wheel-rail vertical force under the action of wheel polygon and track excitation is analyzed.The calculation results show that when the vehicle running speed is low,the wheel polygonization will form low-frequency vibration,which will increase the vehicle body vibration response;Wheel polygonization will greatly increase the wheel-rail vertical force,but has little effect on the derailment coefficient and the stability index.The wave depth limit is inversely proportional to the vehicle running speed and the wheel polygon harmonic order;the track excitation will not only cover the role of the polygon,but also greatly increase the wheel-rail vertical force.By comparing the Archard and wear power model,a wheel polygon wear model based on wear power is established.On the premise of considering both calculation efficiency and result reliability,the wear calculation step and update strategy are determined,and 2000 sampling points and 0.02 mm wave depth are selected respectively.Then based on the model,the effects of curve condition,track excitation,initial wheel polygons and vehicle running speed on polygon wear are studied.The wheel circumferential wear during vehicle operation is divided into two parts: the equivalent wheel circumferential wear and the wheel polygon wear.The results show that the curve condition and track excitation will greatly increase the equivalent circumferential wear,but have little effect on the evolution trend of wheel polygon;when the wheel is initially elliptic,the wheel will gradually evolve into a high-order polygon,but the trend is random;when the wheel is initially 3 or 4-sided,the wheel will gradually evolve into a hybrid polygon composed of several-order integer-times initial polygon.Through polygon wear simulation,the vehicle dynamic performance in each evolution stage of wheel is calculated.The calculation results show that with the increase of vehicle running mileage,the vertical force of wheel-rail increases slowly and then sharply,and even the phenomenon of jumping the track occurs.The vibration acceleration of car body and frame changes little,while the vibration acceleration of wheelset increases gradually,and the stability index and derailment coefficient change little.The factors affecting the wear rate of wheel polygon are studied by polygon wear simulation.The calculation results show that the wave depth of wheel polygon decreases slowly and then increases sharply with the increase of vehicle running mileage,while the wear rate increases slowly and then rapidly.The higher the initial wave depth and order,the smaller the wheel radius and the faster the vehicle running speed,the faster the polygon evolution rate will be.When the phase of the left and right wheel polygons is different,the wear of one of the wheels will be accelerated.Wheel wear rate is the highest when the phase difference between the left and right wheels of the wheelset is 1/2 cycle,that is,when the wave trough on one side of the polygon wheel corresponds to the wave peak on the other side.