Wheel-rail Contact Geometry And Optimal Design Of Rail Profile In Complex State

The wheel-rail contact geometry is a key indicator of the wheel-rail matching performance,and plays a decisive role in the wheel-rail and vehicle dynamic performance.In recent years,our country’s high-speed,heavy-haul railways and urban railway have developed rapidly.The force between the wheel and rail has intensified,the vibration and impact of the wheel and rail are frequent,and the contact relationship between the wheel and rail has become increasingly prominent,which seriously affects the fatigue of structural components and reduces the service life of the wheel and rail.Grinding the rail to the design target profile can improve the wheel-rail contact relationship and improve the vehicle dynamics.It is helpful for the optimal design of the rail profile to caculate and analysis wheel-rail contact character.The complex state of the site from two dimensions are defined.First,the line type is complex,the wheel and rail damage types are diverse,and the radius of the curve line and the distribution of the rail bottom slope are obviously different.Second,the test data is complex.Due to the different test equipment,the data file format is complex,the data quality is uneven,and the data content is diverse.In this thesis,according to the complex track profile of the measured line,the wheel-rail contact geometric algorithm program is written,the contact geometric relationship is analyzed,the optimal design model of the polished rail profile is established,and the profile optimization design method is used to establish different optimization objective functions to carry out the rail profile optimization design.Finally,the wheel-rail matching performance of optimized rail profile is analyzed.The main works and conclusions of the paper are as follows:(1)A batch calculation software for wheel-rail wear and wheel-rail contact geometric relationship is written.One-click automatic generation of wheel-rail contact geometric relationship calculation report is realized.Using the self-compiled software,the calculation and analysis of the wheel-rail contact geometric relationship of the measured line is carried out,the characteristics of the wheel-rail contact relationship of the line are clarified,the wear characteristics of the wheel-rail geometric profile are clarified,and the complex wheel-rail system parameter state and the wheel-rail contact relationship are mastered.(2)An optimal design method of rail profile geometry is established,which combines NURBS curve parameterization,genetic evolution algorithm and vehicle-track dynamics model.The method determines the design variables,the wheel-rail contact dynamics optimization index,and designs the optimization objective function and optimization constraints.The optimization parameters of the genetic algorithm are optimized through multiple experiments,and the genetic operator with the threshold parameters of the iterative stop condition are obtained,and the optimized rail profile is obtained by solving.(3)Using the established rail profile optimization design method,the rail profile was optimally designed considering the wheel-rail contact performance and dynamic indicators under different wear conditions of the car profile,and compared with the optimized rail under the condition that only the standard car profile was considered.The results show that the optimally designed rail profile obtained by considering different wear states of various vehicle profiles has a better wheel-rail contact performance.(4)The rail grinding profile automatic alignment algorithm and grinding volume calculation method is bulit.The grinding volume optimization index is focused to optimize the grinding profile design of the rail profile based the rail profile optimization method.Different weight coefficients of wear,wheel-rail contact stress,and rail grinding amount are compared and analyzed for the iterative evolution process of the wheel-rail optimization index for optimizing the rail profile.The results show that it is better to optimize the wheel-rail wear,wheel-rail contact stress and rail grinding amount at the same time.