高速铁路钢轨预打磨型面优化分析

Optimal Analysis on Rail Pre-grinding Profile in High-speed Railway

高速铁路的发展使钢轨磨损和滚动接触疲劳损伤日益受到重视。研究表明,预打磨后钢轨可有效延长服役寿命。为实现预打磨最佳廓形的选择,基于蒙特卡洛方法建立假设轮对横移量服从高斯分布的轮轨接触概率分析模型。据此,确定出列车运行时考虑轮对横移量的轮轨接触位置,并采用轮轨三维有限元模型计算得到相应接触应力的概率分布。结果表明,轮对横移量对最大接触应力值具有显著影响,横移量为10 mm、0 mm、8 mm时其值分别为1 712.6 MPa、1 362.1 MPa、448.7 MPa。亦发现虽然累积接触应力和平均接触应力均可作为衡量不同钢轨廓形力学性能优劣的指标,但二者的预测结果并不一致,如60 kg/m(CHN60)钢轨的平均接触应力,在轨距角附近(距钢轨中心线30 mm处内侧)的值4倍于踏面中心区域,相应的累积接触应力,在踏面的中心区域的值则接近10倍于轨距角附近。为综合考虑钢轨累积接触应力和平均接触应力对预打磨型面的影响,提出加权累积和平均接触应力,并以此作为钢轨预打磨廓形优化的评价指标。依据该指标对按照打磨工程经验设计的四条钢轨预打磨廓形进行评价分析,得到较优的钢轨打磨廓形。对制定钢轨廓形优化和打磨方法具有一定的工程参考价值。

With the development of high-speed railway,more and more attention has been focused on the rail damage caused by wear and rolling contact fatigue,and it is found that rail service life could be extended by the pre-grinding technology.To determine the optimal pre-grinding profile,a probability model of wheel-rail contact based on the Monte Carlo method is proposed,in which the lateral displacement of wheel set is assumed to follow the Gauss distribution.The probability distributions of contact stress of rail are obtained by a three-dimensional finite element model in which the lateral displacement of wheel set is defined by the probability model,while a train passing.The results show that there is a significant influence of lateral displacement on the maximum contact stress,while the lateral displacement varies with 10 mm,0 mm and 8 mm,the corresponding maximum contact stress are 1 712.6 MPa,1 362.1 MPa and 448.7 MPa respectively.Although the value of accumulated or average contact stress could be employed as a index to evaluate the mechanical properties of a rail profile,the prediction results are not consistent with each other,for instance,the average contact stress of CHN60 at inner rail corner（within 30 mm from the rail tread central area） is nearly four times of that at rail tread central area,while the value of accumulated contact stress at rail tread central area is 10 times larger than that at inner rail corner.For avoiding the contradiction,a weighted index which both considering the accumulated contact stress and the average contact stress is proposed and used for evaluating the rail pre-grinding profile.An optimal profile is determined from four types of rail pre-grinding profiles which are designed by the engineering experience according to the weighted index,that is,the minimum value of the index for the rail pre-grinding profile.The present work would be a certain reference value for drawing up the rail profile optimization and rail grinding methods.