Mechanical Analysis And Optimization Design Of Wheel Rail Contact At Rail Gap

Rail joints are one of the three weakest parts of railroad lines.The damage of wheel-rail at the rail joints will increase with the train speed and axle weight,and the study of such problems has been the focus of many scholars.In other words,the study of wheel-rail contact mechanics at rail joints is crucial to the safe vehicle operation and the reduction of cost of railroad operating.In this paper,the mechanical problems of wheel-rail contact at the rail joints are analyzed and optimized.The mechanical characteristics of wheel-rail contact at the rail joints with different geometrical profiles are also discussed.Based on the finite element method,the wheel-rail elasto-plastic contact calculation analysis is carried out,and the distribution of wheel-rail contact stress is also calculated.Firstly,using the wheel-rail contact geometry principle and the elasto-plastic finite element contact calculation theory,the contact stresses between various locomotive wheels with different geometric profiles and the 60kg/m rail at different widths of rail joints are analyzed and modeled.Then,the contact mechanics of locomotive wheels at the 8-16 mm rail joints when offsetting occurs is investigated.JM,JM2,JM3 tread wheels and 60kg/m rails are selected to study the effect of wheel-rail profile matching on the contact mechanics when wheels with different geometrical profiles are traversed at the rail joints.Based on the results of numerical calculations,the stress variation law of the wheel and rail in contact with each other at the rail joints is examined.The above calculation and analysis results are used as a basis to optimize the design of rail geometry.The experimental results yielded that the presence of rail joints led to a significant change in contact stress concentration in the rail.Stress from the internal transfer to the surface,and it is easy to cause damage to the surface layer of the rail.With the increasing width of the rail slit,the wheel and rail contact stress also increase.As a result,within the scope of the project allowed,engineering designers should try to reduce the width of the rail slit.Considering the change of wheel-rail matching relationship between straight section and the multi-curve section,it is recommended to use JM type tread wheel with 60kg/m rail matching in plain area,and JM3 type tread wheel with 60kg/m rail match in mountainous area.The optimization method of adding chamfer or rounded corner to the rail end at the rail seam can effectively reduce the maximum equivalent force of the wheel at the rail seam and prolong the service life of the rail.