Study On The Influence Of Different Wheel Wear Forms On The Safety Performance Of Vehicle Operation

Urban rail transit is the main traffic force of large and medium-sized cities,which provides great convenience for people’s life.In the operation of urban rail transit vehicles,the wheel-rail wear problem is becoming increasingly serious.The common wear forms include concave wear,polygonal wear and flat scar.In this paper,the influence of the above wear forms on the dynamic safety of metro vehicles was studied.A rigid and flexible coupling dynamics model of a metro B vehicle with wheel-rail flexibility was established,and the influence of different wear forms on the vehicle dynamic operation and wheel-rail dynamic contact safety performance was calculated.The safety performance of the vehicle dynamic operation includes whether the derailment coefficient of the vehicle through the straight and curve segments,the load reduction rate of the wheel weight,the lateral force of the wheel shaft and the overturning coefficient exceed the safety limit;Vehicle running stability;Vibration of key components and vibration and displacement of track lines.The safety properties of wheel-rail dynamic contact include wheel hedge Angle,wheelset transverse movement,abrasion index based on creep force,etc.Archard wear model was used to predict concave wear of wheel,polygon wear of wheel was used to represent harmonic function,and flat scar damage of wheel was represented by old and new flat scar circular Angle formula.The main research work was as follows:(1)According to the development characteristics of concave wheel grinding,the concave wheel wear surface under different operating mileage was predicted,and the geometric relationship of wheel rail contact,equivalent taper,contact stress,contact spot,difference of rolling circle radius and nonlinear critical speed were calculated.The results showed that,with the increase of operating mileage,the matching between concave grinding surface and rail contact point became intensive from dispersion.At 3mm,the equivalent taper and the difference of rolling circle radius gradually increase,and the nonlinear critical velocity gradually decreases,but the vehicle curve passing performance is improved.The contact stress decreases first and then increases and decreases,and the change of contact spot area is just opposite to the contact stress.(2)Due to the large correlation between vehicle running quality and safety performance,running quality is reflected in wheelset vibration,axle box vibration,rail vibration and displacement size,vehicle stability and comfort.The influence of different wear forms on running quality is analyzed and its importance is found.Compared with polygon and concave grinding,flat scar has the largest influence on wheelset vibration,axle box vibration,rail vibration and rail vertical displacement,followed by polygon influence and concave grinding influence.In the stability and comfort,flat scar has the greatest influence,polygon wear is moderate,concave wear has little influence.The expansion of different wear forms will cause different degrees of damage to the track line.Therefore,preventing the expansion of different wear forms can alleviate the safety risks caused by the fatigue of the track and components.(3)Through the analysis of the safety limits of vehicle dynamic operation in different wear forms,there is no derailment phenomenon in the evolution of wheel concave wear;Polygon wear excitation is obvious,the vehicle derailment will occur;Compared with the previous year,flat wheel scar had the greatest impact on vehicle safety.According to the influence of the above different wear forms on derailment safety,the safety limits of different wear forms on vehicle dynamic operation were formulated,and the corresponding repair feed amount was proposed based on the corresponding dynamic safety indexes of different wear forms,which provided engineering application value for the subsequent vehicle operation.(4)According to the characteristics of vehicle running in curve section,the influence of different wear forms on vehicle dynamic contact safety was studied.The dynamic contact values of guide wheel and follower wheel were extracted as Angle of impact,transverse displacement of wheelset,and wear index respectively.The analysis showed that with the development of various wear forms,the Angle of impact gradually increased,the mutation Angle of follower wheel was greater than that of guide wheel,and the shaking amplitude of wheel was increased.Not conducive to vehicle curve running.With the development of various types of wear,the transverse movement of wheelset strengthens the jump of contact point,increases the volatility,and worsens the serpentine stability of vehicle.The wear index greatly increases in the form of flat scar,followed by polygon wear,and finally concave wear.The evolution process is also from wear dominated to fatigue dominated,resulting in increased hidden danger of vehicle safe operation.