Effect Of Anti-slip Parameters On Wheel Wear Of High Speed Vehicle

The increase of railway speed means the vehicle needs better performance during braking.Wheel/rail low adhesion causes the wheel to slip,resulting in wheel tread abrasion or excessive wear,and extending the braking distance of trains.Anti-slip control is the most important part of braking control technology.Most of the researches pay little attention to wheel wear during braking anti-slip.In view of the above reasons,it is necessary to study the influence of anti-slip braking control on wheel wear to provide reference for the anti-slip threshold specification which is one of the selection criteria for wheel wear in the anti-slip control.The main contents of this dissertation are as follows:1.The model of anti-slip braking control system of high-speed vehicle is established with the non-linear characteristics of brake cylinder pressure,which includes dynamics model of vehicle system,anti-slip braking control with logic gate,and calculation module of non-linear braking force.Vehicle system dynamics model is created with the multi-body dynamics software SIMPACK.MATLAB/Simulink is employed to develop other parts of the model.The anti-slip process of vehicle braking is realized by using the method of joint simulation.2.Under the condition of low adhesion of oil,influence of anti-slip control threshold of deceleration on wheel wear is discussed firstly.The influence of creep rate method on wheel wear is discussed,which includes different control strategy,sliding mode and creep rate threshold.3.The variation characteristics of wheel wear are studied when creep rate method and deceleration method work together to prevent slipding.Influence of different creep threshold on wheel wear is also discussed with deceleration control.An optimization proposal of anti-slip parameters based on wheel wear control and braking performance is put forward.Through the above research,it is found that:(1)During the air emergency braking with the condition of low adhesion of oil,the fluctuation amplitude of wheel/rail longitudinal creep rate/force increases with the decrease of vehicle speed.The average value and fluctuation amplitude of wheel wear index increase with the decrease of vehicle speed.(2)When the deceleration method is used alone,the deceleration threshold a_B is in the range of 2~2.5 m/s~2,and the average value of the wheel wear index is within 6.9%.The threshold a_B is in the range of 2.5~4 m/s~2.As the threshold increases,the wheel wear index increases gradually.When the deceleration threshold a_D is in the range of 0.5~4 m/s~2,wheel wear index decreases first and then increases with the increase of deceleration threshold a_D.The thresholds of minimum wear value are 2.5 m/s~2 and 3.0 m/s~2 respectively in 100~0 km/h and 300~100 km/h.(3)It is recommended to use emergency braking under the condition of low adhesion of oil,the control strategy of creep rate method alone is better to adopt direct exhaust air action.There is a significant difference of the wheel wear in full-axle and single-axle slip,especially when the creep rate threshold is 0.15,the average value of the wheel wear index is 382 N at a speed of 150~100 km/h..It shows that the accuracy of reference velocity has a great influence in wheel wear.When the creep rate threshold is in the range of 0.01~0.14,wheel wear index increases linearly with the increase of creep rate threshold.(4)Integrated anti-slip control can effectively reduce the wheel wear index.After the deceleration method is considered,the average value of the wear index can not change when the creep rate threshold is increased to a certain value,and the threshold of the certain value decreases as the speed increases.(5)Considering the influence of deceleration threshold and creep rate threshold on wheel wear index and braking distance,anti-slip parameter thresholds are proposed under the condition of low adhesion of oil with air emergency braking as follows:the deceleration threshold a_B is recommended to be 2.5 m/s~2;the deceleration threshold a_D is recommended to be 3.0 m/s~2;and the creep rate threshold is recommended to be 0.15.