| With the rapid development of railways today,the problem of railway line wear is becoming increasingly serious,especially for the dynamic characteristics and wheel rail wear of heavy-duty railways in small radius curve sections.This article summarizes the current research status of wheel rail power and wheel rail wear on heavy haul railways both domestically and internationally.Based on the coupled dynamics theory of heavy haul railway vehicle track system and rail wear theory,a model of heavy haul freight cars and a prediction model of wear evolution surface are established using the multi body dynamics software UM.By changing the parameter values of different small radius curve sections,the dynamic characteristics and changes in wear degree of heavy haul railway wheels and rails under different working conditions are studied and analyzed,And analyze the changes in wheel rail dynamic characteristics caused by wear evolution under different curve parameter conditions,and determine the range of small radius curve section parameters that can be suitable for the rapid development of heavy-duty railways,reduce wheel rail contact wear,and improve railway throughput.The specific research content and results are as follows:(1)Based on the coupling dynamics theory of heavy-duty railway vehicle track and wheel rail wear theory,a C80 freight car model,a moving mass track model,a wheel rail contact model,and a wheel rail wear prediction model for heavy-duty freight cars are established using UM software.The wheel rail dynamic characteristics and wear evaluation indicators are determined,and the model is validated through critical speed method and reference comparison.(2)Based on the established heavy-duty vehicle track coupling dynamic model and wheel rail wear prediction model,analyze the influence of different curve parameters on the wheel rail dynamic characteristics and rail wear degree when heavy-duty trains pass through small radius curve sections:①As the curve radius increases from 600 m to 1000 m,the amplitudes of various indicators that affect the dynamic characteristics of the wheel rail gradually decrease with the increase of the curve radius.The cumulative wear depth and wear power of the steel rail gradually decrease with the increase of the curve radius,and the amplitude difference and numerical fluctuation range of various indicators in the curve and straight section also gradually decrease.②When the outer rail superelevation is under the condition of under superelevation,as the under superelevation gradually increases,all indicators of wheel rail dynamic characteristics show a gradual increasing trend,with a relatively gentle increase.The depth and power of rail wear also gradually increase with the increase of under superelevation,and the amplitude difference and numerical fluctuation range of various indicators in curve section and straight line section also gradually increase;When the outer rail superelevation is under the condition of over superelevation,as the over superelevation gradually increases,all indicators of wheel rail dynamic characteristics show a gradually increasing trend,with a more significant increase in amplitude;The depth and power of rail wear also gradually increase with the increase of over height.③As the length of the transition curve increases from 60 m to 100 m,the amplitudes of various indicators that affect the dynamic characteristics of the wheel rail gradually decrease with the increase of the transition curve length.The depth and power of rail wear gradually decrease with the increase of the transition curve length,and the amplitude difference and numerical fluctuation range of various indicators in curve and straight sections also gradually decrease;In order to improve the dynamic characteristics of the wheel rail,reduce the degree of wheel rail wear,and enhance the passing capacity of the line,the minimum recommended length of the transition curve for small radius curve sections of heavy-duty railways is 70 m.④As the operating speed increases from 40km/h to 80km/h,the amplitudes of various indicators that affect the dynamic characteristics of the wheel rail gradually increase with the increase of operating speed.The depth of rail wear and the power of wear significantly increase with the increase of operating speed,and the amplitude difference and numerical fluctuation range of various indicators in curve and straight sections also gradually increase.⑤As the rail bottom slope increases from 1/45 to 1/20,the amplitudes of various indicators that affect the dynamic characteristics of the wheel/rail gradually increase with the increase of the rail bottom slope.The depth and power of rail wear gradually increase with the increase of the rail bottom slope,and the amplitude difference and numerical fluctuation range of various indicators in curve and straight sections also gradually increase.Due to the small rail bottom slope,the rail will be subjected to centrifugal load.When a heavy-duty train passes through a small radius curve section,the recommended value for the rail bottom slope is 1/40.When a heavy-duty train passes through a small radius curve section,under different curve parameter conditions,as the running distance gradually increases,the lateral force of the wheel rail,derailment coefficient,wheel load reduction rate,and lateral acceleration of the vehicle body all show a trend of first increasing and then decreasing.The vertical force of the wheel rail and vertical acceleration of the vehicle body always maintain a stable fluctuation state;The outer rail always experiences lateral wear,while the inner rail experiences vertical wear.As the curve parameters continue to change,the position of rail wear also gradually changes.(3)Based on a wheel rail wear prediction model,analyze the changes in the dynamic characteristics of heavy-duty railway wheels and rails caused by different wear evolution states under different curve element conditions:①Under different curve radius conditions,as the degree of wear evolution gradually increases,the amplitude of various indicators of wheel rail dynamic characteristics also gradually increases.Under different wear evolution states,trains and rails are in different running in periods,and the amplitude of each indicator increases differently.Moreover,under certain wear evolution conditions,the amplitude difference of each indicator of wheel rail dynamic characteristics decreases with the increase of curve radius.When the curve radius is greater than 800 m,the difference in amplitude of wheel rail dynamic characteristics decreases more significantly.It is recommended that the curve radius in small radius curve sections of heavy-duty railways should be greater than 800 m as much as possible.②Under different conditions of outer rail superelevation,as the number of train operations increases,the amplitude of dynamic characteristics indicators under different conditions of outer rail superelevation gradually increases.When the outer rail superelevation is in under superelevation,the amplitude difference of wheel rail dynamic characteristics indicators decreases with the increase of under superelevation.When the outer rail superelevation is in over superelevation,the amplitude difference of wheel rail dynamic characteristics indicators increases with the increase of over superelevation.When a heavy-duty train passes through a small radius curve section,an appropriate under elevation value can be taken for the outer track of the curve to reduce wheel rail wear and improve wheel rail dynamic performance.③Under different operating speed conditions,as the number of train operations increases,the amplitude of various indicators of wheel rail dynamic characteristics gradually increases;Under the same condition of wear evolution,the amplitude difference of wheel rail dynamic characteristics indicators under different operating speed conditions gradually increases.In order to improve the wheel rail dynamic characteristics and reduce the degree of wheel rail wear,it is recommended that the design speed of small radius curve sections of heavy-duty railways should be as low as 80km/h. |
PDF Full Text Request