Research On Influence Of Temperature Rising Of Tread Braking On Wheel Wear

The wear between wheel and rail has been a difficult and important part in railway industry.With the increase of axle load and vehicle speed,the wear between wheel and rail is more serious.In addition,tread brake is widely used in truck and metro vehicles,making the wheel tread temperature rise sharply,up to 300 ? in the process of train braking.Due to the influence of the temperature rise of the wheel tread,mechanical properties of the wheel surface is changed and it has changed the wheel/rail contact state and wear resistance,eventually making an impact on the wheel wear.In order to be more accurate to simulate the wheel wear in the process of the wheel tread braking,in this paper,a finite element method is proposed to calculate the temperature rise of the intermittent heat source method which can take account of both the accuracy and the computational efficiency and a wheel wear model considering temperature effect is established.The model can more accurately predict the wheel wear,and provide a theoretical basis for repairing the wheels spin cycle.The main contents of this thesis include:1.The research methods and present situation of wheel wear and wheel brake temperature rise at home and abroad are discussed in detail,and the importance of the brake temperature influence on abrasion and the research significance and purpose of this article is clarified.2.In order to overcome the shortcomings of the traditional loading method for simulating the friction heat flux of wheel tread,this paper proposes a new loading ways of the heat flux of braking temperature finite element numerical method.Taking the emergency braking of heavy-duty trains for example and by means of comparing with the calculation precision and calculation efficiency of the moving heat source method and the uniform heat source method,this paper proved that the intermittent heat source method can not only meet the calculation precision of moving heat source,also can achieve the computing efficiency of uniform heat source method,and also can response temperature fluctuations features caused by the brake shoe and the contact between the tread-from-contact physical phenomena that uniform heat source method can't reflect.3.Based on the theory of material mechanics and the experimental data,the relationship between the mechanical properties of steel and the temperature was established and modified with the measured data.The relationship between the tensile strength,the elastic modulus,the friction coefficient and the hardness of the wheel material with the brake temperature rise can be obtained by combining the temperature rise of the tread surface with time.4.Based on the Archard wear model and the variation of mechanical properties of wheel steel material with temperature,a wheel wear model which can consider the temperature effect is established.The effect of the temperature rise on the wheel wear is considered from two aspects:one is the influence of the temperature on the division of the contact patch,and the influence of the temperature on the parameters related to the wear calculation.5.This paper analyzes the emergency braking and the long ramp braking of heavy load trains under typical braking conditions,and the division of the contact area of the wheel and rail contact spot at the highest temperature rise.When the wheel is rolled over a contact sport.The wear depth and wear depth of the wheel tread are calculated throughout the braking cycle.The wear volume and wear depth of the wheel tread during the whole braking cycle are also calculated.The effects of brake temperature rise on wheel wear are analyzed and compared,and the total volume of wheel wear is increased and the wear volume is increased when the brake temperature rise is taken into account.