Influence Of Wheelset Flexibility On Wheel-Rail Wear And Dynamics Of Linear Motor Vehicle With Inside And Outside Axle Boxes

In the simulation of railway vehicle dynamic performance for actual running condition,the main components of vehicle system are usually considered as rigid bodies connected by suspension,in which the elastic deformations of the parts,such as the wheelset,the bogie and the carbody,are ignored.However,this is only valid for the case of low frequency.In the process of vehicle running,the elastic deformation of wheelset will lead to a change of the relative positions between wheel tread and rail tread,which will have a certain influence on the positions of wheel–rail contact point and vehicle dynamic performance,as well as the wheel–rail wear.There are two types of axlebox arrangements of vehicles on some domestic metro line,namely,the traditional outside axlebox vehicle and the newly developed inside axlebox vehicle.Because of the different positions of the inside axlebox and outside axlebox vehicles,the wheelsets show different bending deformation forms.In this thesis,two types of railway vehicle models,which correspond to the outside axlebox and inside axlebox,are established with main emphasis on the flexibility of wheelset,to study the differences in dynamic performance and the variation law of wheel–rail wear.The current model will lay a foundation for the subsequent indepth research on the dynamic performance of inside axlebox vehicle.At present,inside axlebox bogies have been included in the research plan of future high-speed train,thus,the research strategies and results of this thesis will also shed some light on the design and the optimization of the high-speed railway vehicle with inside axlebox.In this thesis,based on the finite element software ANSYS and dynamic software SIMPACK,wheel–rail geometrical contact model,vehicle models which take two types of axlebox arrangements and wheelset flexibility into account,and wheel–rail wear model are established to analyze the influence of axle bending deformation on wheel–rail contact,dynamic performance and wheel–rail wear of vehicles with inside and outside axleboxes.The main work and conclusions of this thesis are as follows:First of all,based on the established wheel–rail geometrical model,the variation law of wheel–rail contact parameters caused by the wheelset bending deformation for vehicles with inside and outside axleboxes is investigated,and the influences of two kinds of axle bending deformation on the position and contact stress of static wheel–rail contact point are studied.The result show that:(1)When the vehicle is running,the axle of the vehicle with inside axlebox will experience concave bending,and the axle of the vehicle with outside axlebox will have convex bending.With the increase of axle load,the wheel deflection angles caused by wheelset flexibility increases.(2)When the wheelset lateral displacement is in the range of 0–6 mm or 9–12 mm,the positions of the wheel–rail contact point of two models are basically the same.When the wheelset lateral displacement is between 6 and 9 mm,the positions of the wheel–rail contact points of two models changes obviously,and the contact points of inside axlebox vehicle are more inclined to the gauge corner.(3)From the wheel–rail static matching,it can be seen that the equivalent conicity of vehicles with inside and outside axleboxes are basically the same when the wheelset lateral displacement is between 0 and 3 mm.When the wheelset lateral displacement is between 4 and 12 mm,the equivalent conicity of vehicle with inside axlebox is greater than that of vehicle with outside axlebox.Therefore,the vehicle with inside axlebox also has better curving performance.(4)For the wheelset lateral displacements in the range of 0–6 mm,both the contact patch shapes of two types of vehicle are approximately elliptical,and the von Mises equivalent stresses and contact stresses are almost the same.Secondly,the influence of axle bending deformation on the dynamic performance of vehicles with inside and outside axlebox is analyzed.The results show that the wheelset flexibility slighly reduce nonlinear critical speeds of vehicles with inside axleboxes and slighly increase nonlinear critical speeds of vehicles with outside axleboxes.When the wheelset lateral displacement is between 6 and 9 mm,if the wheelset flexibility is considered,the wheel–rail vertical force,lateral axle force,derailment coefficient and wheel load reduction rate of the vehicle with inside axlebox increase slightly.The axle bending deformation has the greatest influence on the derailment coefficient of vehicle with inside axlebox,the increase is 5.1%.Except for the wheel load reduction rate,the other indexes of vehicle with outside axlebox decrease slightly.It has the greatest impact on the lateral axle force of vehicle with outside axlebox,the decrease is 6.2%.Finally,based on the wheel–rail wear model and Elkins wear index,the influences of wheelset flexibility on wheel–rail wear of the above two types of railway vehicles are studied.When considering the flexibility of wheelset,the conclusions are as follows:(1)For vehicle with outside axlebox passing through curves,when the wheelset lateral displacement is between 6 and 9 mm,the top wear and side wear of high rail are reduced,and the wear position is slightly away from the gauge corner.The wear amount of high rail corresponding to the vehicle with inside axlebox is also reduced,and the wear position moves towards the gauge corner.(2)The wear index of the wheel decreases in both curve and straight lines.The maximum reduction of wear index for vehicle with outside axlebox is 8%,and that for vehicle with inside axlebox is 12%.At the same time,it can be seen from wheel–rail wear calculation that the wheel wear positions of vehicle with inside axlebox move towards the flange side,and those of vehicle with outside axlebox move towards the tread side.