Study on evolvement rule of the polygonal wear of EMU wheels and its effect on the dynamic behavior of a vehicle system
In order to study the evolution of EMU wheel polygons and the influence of polygons on vehicle dynamics during the running process, the vehicle-track dynamics model of EMU was established in SIMPACK software. The wear law of the wheel is explored by using the measured polygonal data which combined with the wheel mass loss model, and the wheel polygon is mostly expressed in 1st order and 20th order polygons with the increase of running mileage. The statistical results show that the 1st order polygon obeys the exponential distribution and the 20th order polygon obeys the positive distribution, which their goodness of fitting is relatively high, 0.96351 and 0.98667 respectively. Using the Fourier series to simulate the wheel polygon, the influence of the different polygon depth and order on the dynamic performance of EMU is simulated by SIMPACK calculation. The simulation results show that the influence of the high order polygon on the dynamics is much higher than that of the low order polygon; the vertical force of the wheel and rail, the derailment coefficient and the vertical vibration of the wheel are increasing with the increase of the polygon depth; and the influence on the vehicle’s Sperling index is relatively small with the wheel polygon formation. It is found that the wheel polygon phenomenon has great influence on the vehicle dynamics.