Study About The Effect Of Wheel Polygons On Vehicle Dynamics Based On Flexible Wheel-track Structure

With the rapid development of China’s high-speed railway and the continuous increase in operating speed,the long-term operation of high-speed railroad vehicles produces wheel wear under the wheel-rail interaction,in which certain wheels produce polygonal wear with obvious harmonic order.The wheel polygonization directly changes the wheel-rail contact relationship and affects the dynamics of the entire rail-vehicle system.Severely worn polygonal wheels deteriorate the vehicle dynamics and have a serious impact on the safety and comfort of the vehicle operation and the service life of the vehicle components,while the inherent frequency between the rail-vehicle and the excitation frequency caused by the polygonal wheels will resonate,and this resonance frequency will aggravate the formation and development of wheel polygons.Based on the theory of multi-rigid body dynamics,this paper firstly establishes a multirigid body system dynamics vehicle simulation model with a certain type of high-speed moving vehicle as the research object.Then the differences in operational smoothness,non-linear critical speed and curve passing performance between the multi-rigid and rigid-flexible coupled vehicle models are compared through calculation and analysis;finally the rigid-flexible coupled model based on the flexible wheel-rail relationship is described using the harmonic function method for wheel polygons,and the effects of the order and the amplitude of out-of-roundness of polygonal wheels on the vehicle dynamics performance at different vehicle speeds are investigated.The results show that,compared with rigid wheel pairs,flexible wheel pairs reduce the non-linear critical speed of vehicle serpentine motion;improve the vehicle lateral smoothness,and in the design speed range of 200km/h,flexible wheel pairs reduce the vehicle derailment coefficient,wheel weight reduction rate and wheel-rail(axle)lateral force;considering only wheel pair flexibility,wheel polygonalization reduces the non-linear critical speed of the vehicle,and has little effect on the vehicle operational smoothness The effect on the operational safety of the vehicle is closely related to certain modal characteristics of the vehicle system;when track flexibility is considered,the effect of the polygon order and the amplitude of the out-of-roundness on the wheel-rail vertical forces becomes more pronounced as the speed increases;at a fixed speed,the derailment factor remains relatively stable with increasing polygon order compared to considering only the wheel pair flexibility,when both wheel pair and track flexibility are considered.