Research On Rail Profile Optimization Of Railway Small Radius Curve Based On Particle Swarm Optimization Algorithm

In the next ten years,the development speed of China’s railway will be accelerated and the scale will continue to expand.By 2025,the total scale of China’s railway will reach about175,000 kilometers.The expansion of scale mileage is bound to put forward higher request to the field of railway maintenance.When the train is running,the rail is in contact with the tread of the wheel and directly bears the load generated by the train.Due to the continuous complex interaction between wheel and rail,rail will inevitably appear disease and wear with the increase of line operation time,this phenomenon is more frequent in the curve section of small radius.From the perspective of traditional works,rail profile grinding is an effective means to eliminate rail diseases and delay rail wear in the curve section with small radius.The optimization design of rail profile is the foundation of profile grinding,and the design of target profile is the key point in the whole grinding process.Aiming at the railway curve section with small radius,the purpose of profile optimization mainly includes increasing train curve passing ability,improving wheel-rail contact relationship and prolonging rail service time.Therefore,a reasonable optimization design of the profile of the worn rail in the curve section with a small radius can not only improve the dynamic performance of the train and the wheel-rail contact relationship,but also prolong the service time and maintenance cycle of the rail and improve its service life,which is of great engineering significance for the field of railway works.Based on wheel-rail contact geometry,cubic NURBS curve construction method and improved particle swarm optimization algorithm,a rail profile optimization design method with small radius curve was established to optimize the radius difference of rolling circles,and a rail profile optimization evaluation model was established by combining the vehicle track dynamics model,Archard wear model and wheel-rail contact relationship.Based on the design and evaluation model,the optimization design and evaluation of standard CN60 rail profile were carried out,and the influence of profile optimization on train dynamic characteristics,contact state and rail wear was explored.Based on the design and evaluation model,the measured line wear type rail is optimized.Based on the optimized design results,the line is polished and the grinding effect is accepted.The main work and conclusion of this paper are as follows:(1)The wheel-rail contact geometry was calculated based on the wheel-rail contact theory,the geometric characteristics of NURBS spline curve were established to construct the rail profile NURBS curve,the improved particle swarm optimization algorithm with inertial weight adaptive modification was established based on the standard particle swarm optimization algorithm as the core solution model,and the optimization profile design objective was established based on the rolling circle radius difference.(2)A vehicle-track system dynamics model was established based on UM multi-body dynamics software to calculate the curve passing dynamics performance of vehicles before and after profile optimization design,including derailment coefficient,wheel weight load reduction rate,wheelset lateral movement,wheelrail lateral force,vertical force,wheel hedge Angle and wear index.Based on Archard wear model,a prediction model of rail wear development with small radius curve was established to analyze the development of rail profile wear before and after profile optimization design.(3)Based on the rail profile optimization design method,the standard CN60 rail profile was optimized and the optimization results were put into the evaluation model to explore the influence of profile optimization on dynamic characteristics,wheel-rail contact and wear characteristics.The optimization results show that the six dynamic characteristics of the rail are improved,the wheel-rail contact relationship is improved,and the development of wear is controlled.(4)Based on the rail profile optimization design method,the measured wear type rail profile was optimized.The results show that the wheel-rail profile matching performance and vehicle curve passing ability are significantly improved after the measured wear rail profile design compared with that before the grinding design,which is of great significance for prolonging the service life of the rail and improving the dynamic performance of vehicles in the curve section with small radius.According to the designed profile optimization data,the actual line was polished,including the grinding equipment,grinding Angle,grinding car implementation details,etc.The grinding mode was selected to consider the disease profile.After grinding,the rail surface state was tracked and observed,and the rail profile retention ability was evaluated with GQI value.The results show that the rail profile design of the measured line wear profile with small radius curve is effective,and the grinding mode of the profile taking into account the disease is reasonable.Combined with the actual engineering cases,it can be seen that the optimization design method of rail grinding profile based on particle swarm optimization algorithm designed in this paper can effectively remove rail surface diseases and extend rail service time.