Study On Metro Vehicle Dynamics And The Wheel/Rail Optimal Matching Under Rail Cant Coupling Wheel Damage Condition

Due to the slope of the wheel tread,the rail cant need to be set to improve the stability of the wheel-rail contact.The unreasonable setting of rail cant will affect the dynamic performance of the vehicle and will also cause different degrees of damage to the wheel and rail.Wheel damage in the form of wheel surface wear,out-of-roundness causes change in wheel-rail contact geometry and contact mechanical properties,which in turn affects the stability of wheel-rail contact and vehicle dynamics,and also complicates the setting of rail cant.Therefore,it is important to study the effect of coupled wheel damage on vehicle dynamics and the optimal matching of rail cant for wheel maintenance and line design and maintenance.Therefore,it is very important to study the influence of rail cant coupling wheel damage on the vehicle dynamic performance.This provides technical support for wheel maintenance and rail design and maintenance.In this paper,based on the theory of vehicle-track coupling dynamics,a vehicle-track coupling dynamics model is established based on the measured metro vehicle parameters and wheel damage data,and nine external/internal rail cant conditions and three wheel damage conditions(wheel profile wear,wheel diameter difference and wheel out-of-round)are set up to investigate the influence of rail cant coupling wheel profile wear,wheel diameter difference and wheel out-of-round on the vehicle dynamics performance.The paper investigates the optimal rail cant matching under different wheel damage conditions by establishing a multiobjective optimization model based on the entropy weight method,which provides theoretical guidance for the line setting and metro wheel maintenance.The main contents and innovations of this paper are as follows:(1)The LM wheel profile data(referred to as S0,S1,S2 and S3)were measured at 0,50,000,80,000 and 140,000 km,and the wheel-rail contact characteristics and vehicle dynamics of different wheel wear profiles and CHN60 rails under different rail cant were studied.The optimal rail cant matching scheme is calculated by entropy weight method for different line conditions and different wheel wear surface conditions.The results show that the optimum matching solutions for the outer/inner rail cant and wheel wear profile for straight lines and four curves of R300 m,R400m,R500 m and R600 m are(1/20,1/20,S3),(1/30,1/30,S0),(1/20,1/40,S2),(1/30,1/40,S2)and(1/30,1/40,S2)respectively;The optimal external/internal rail cant match corresponding to the wheel wear profile changes for different operating miles,e.g.for the R300 curve,the optimal external/internal rail cant match corresponding to S0,S1,S2 and S3 are(1/30,1/40),(1/20,1/30),(1/20,1/20)and(1/40,1/20)respectively.(2)Five types of wheel diameter difference working conditions were set up,and the influence of the change of rail cant on the dynamic performance of metro vehicles under different wheel diameter difference working conditions was investigated,and the optimal matching scheme of rail cant under different wheel diameter difference working conditions was derived by entropy weight analysis with the evaluation indexes of train straight-line running smoothness and curve passing performance.The results show that the optimal matching solutions for the external/internal rail cant and the wheel diameter difference under straight line conditions are(1/40,1/40,-0.5);under the four curves of R300 m,R400m,R500 m and R600 m,the optimal matching solutions for the external/internal rail cant and the wheel diameter difference are(1/20,1/40,+1),(1/20,1/40,+1),(1/20,1/40,+1)and(1/20,1/40,+1)respectively.1),(1/30,1/30,-1),(1/40,1/30,-1).(3)The effect of rail cant coupling wheel out-of-round on the dynamics performance of metro vehicles is investigated,and the optimal coupling conditions are derived from the dynamics point of view by using the entropy weight method with the evaluation indexes of the train’s straight-line running smoothness and curve passing performance.When there is wheel out-of-round,the optimal matching solutions for the external/internal rail cant are(1/40,1/30),(1/20,1/30),(1/40,1/30),(1/30,1/30)and(1/30,1/30)respectively;when there is no wheel out-of-round,the optimal matching solutions for the external/internal rail cant are(1/40,1/20),(1/30,1/40),(1/30,1/30),(1/30,1/30)and(1/40,1/30)for straight line and R300 m,R400m,R500 m and R600 m curves respectively.