| The abnormal vehicle system vibration leaded by wheel eccentricity and orbital local irregularity which appeared in the track line of some special places should be particularly concerned during the operation of the railway.Wheel eccentricity was simulated by harmonic function method and dynamic model of locomotive was build.The influence of wheel eccentricity amplitude on locomotive dynamic performance was analyzed.Sinusoidal type irregularity and exponential decay type irregularity are simulated by MATLAB software as the locomotive model external excitation.The influence of the amplitude of orbital local irregularity on wheel/rail dynamics was analyzed under different-speed operation by using SIMPACK multi-body dynamics simulation software.Locomotive dynamic response under the action of wheel eccentricity and orbital local irregularity was analyzed on this basis,.The wheel eccentricity produce a specific frequency excitation between the wheel and rail,it have a greater impact on vertical dynamic characteristics of the locomotive and will worsen the three indexes which are axle lateral force,wheelset decreasing ratio,lateral vibration acceleration.The axle lateral force and wheelset decreasing ratio increase regularly with the increase of the wave depth.And the results show that the kinetic indicators will not exceed the limit if the wave depth was less than 2.0mm during the speed of 80～160km/h.The sine-type local irregularity has obvious effect on the vertical dynamic characteristics of the locomotive.The dynamic index as axle lateral force,wheelset decreasing ratio,and vertical vibration acceleration will have an obvious diffusion and convergence process under the action of this excitation.The dynamic indexes deteriorate as the driving speed increases.The lateral vibration acceleration easily exceeds the limit when the driving speed is slightly faster.Exponential decay type irregularity has a significant influence on the vertical and lateral dynamic characteristics of the locomotive.The indexs as wheel/rail vertical force,axle lateral force,wheelset decreasing ratio,and lateral vibration acceleration will have an obvious diffusion and convergence process under the action of this excitation.The dynamic indexs will exceed the limit when the driving speed is slightly faster.Especially,axle lateral force and wheelset decreasing ratio will diverge and converge at the same frequency and amplitude at the same time.Sometimes the two indexes may exceed the limit at the same times which will have a great threat to the security of the locomotive.The changing rule of the locomotive dynamic indexes under the composite action of Wheel eccentricity and orbital local excitation synchronizes with locomotive performance only under the action of the orbital local excitation.Dynamic index will diverge and converge at the same frequency,and also will reach the maximums and minimums at the same time.But every dynamic index is worsen under composite excitation.As for the composite excitation of "wheel eccentricity + sine-type local irregularity",,the wheelset decreasing ratio reach 0.91 which beyond the limit when the speed is 150km/h.As for the composite excitation of "wheel eccentricity + exponential decay type irregularity",the wheel/rail vertical force,wheelset decreasing ratio will exceed the limit.In addition,when wheel/rail vertical force and wheelset decreasing ratio exceed the limit and the speed is lower than it only under the action of exponential decay type irregularity. |
