关键词：钢轨；滚动接触疲劳；无损检测；交流电磁场检测；磁场响应中图分类号：TH89DOI：10.3969/j.issn.1004-132X.2025.04.020 开放科学（资源服务）标识码（OSID）：

Reconstruction of Magnetic Field Responses Caused by Rail Surface Cracks with Alternative Current Excitation

WANG Chi1'² ZHOU Yu^1，2 ？ WENG Zhiyi1，2 1.Key Laboratory of Road and Traffic Engineering of the Ministry of Education，Tongji University， Shanghai，201804 2.Shanghai Key Laboratory of Rail Transit Structure Endurance and System Safety，Tongji University，Shanghai，201804

Abstract： As the response laws of the perturbed magnetic field in ACFM to rail RCF crack morphology parameters remained unclear，a novel method was proposed for functional reconstruction between the ACFM perturbed magnetic field and rail RCF crack parameters. The ACFM calculation models were established based on multiple field tests of surface length，elipse ratio，and internal angle of RCF cracks in heavy-haul railway rails throughout their full life cycle. The perturbed magnetic field above RCF cracks with different parameters was numerically calculated using the ACFM model. The relationship between RCF crack parameters and the perturbed magnetic field was systematically analyzed. Through fiting and evaluation of the perturbed magnetic field's response to the spatial morphology parameters of RCF cracks， the functional expression of the response laws was reconstructed. The results demonstrate that the ACFM response to rail RCF crack parameters is synthetically characterized. The peak value of magnetic field x -component is observed to increase linearly with the surface length and nonlinearly with the internal angle of RCF cracks.Conversely，a nonlinear decrease may be identified as the ellipse ratio of RCF cracks increases. These variations are effectively described by polynomial functions. The change rules between the perturbed magnetic field and RCF crack parameters may be functional reconstructed. The determination coeficient between the reconstructed results and the perturbed magnetic field is found to exceed 0.99，while the sum of squared errors（SSE） and root mean squared errors（RMSE） are constrained to less than O.Ool 15 and 0.Oo3，respectively.

Key words： rail;rolling contact fatigue（RCF）； non-destructive testing； alternative current fieldmeasurement（ACFM） ；magnetic response

0 引言

在轮轨接触引起的周期性切向力与牵引力反复作用下，钢轨表面特别是轨距角应力集中区域极易因滚动接触疲劳（rollingcontactfatigue，RCF）而产生裂纹。这种表面滚动接触疲劳裂纹持续发展可能造成剥离掉块或与其他因素共同作用引起断轨[2]，从而缩短钢轨使用寿命，影响轨道交通安全运行。裂纹在钢轨表面和内部的空间走向影响着钢轨近表面探伤与养护策略，因此掌握钢轨滚动接触疲劳裂纹的空间形态特征势在必行。现有研究表明，钢轨轨距角处的滚动接触疲劳裂纹具有复杂的空间特征，如与行车方向和钢轨横向均存在一定的夹角，夹角大小与轮轨接触关系有关，表面长度随着通过总重的累积而增加[3]，内部深度随轮轨接触作用、钢轨磨耗[4]及液体侵入[5而发生抑制或扩展。CT扫查结果表明[6]，由裂纹表面开口长度、内部倾角以及口袋深度所确定的半椭圆是对钢轨轨距角处滚动接触疲劳裂纹空间形态参数的一种合理近似。

不同于视觉检测[、漏磁检测[8]、电涡流检测[9]等方法，交流电磁场检测（ACFM）[10-11]方法通过在试样表面感生均匀电流并测量其上方磁场扰动来实现裂纹内部参数的非接触激励测量。对发生于管道[12]、石油平台[13]场景中的应力腐蚀裂纹有较好的检测效果。因此通过交流电磁场检测方法进行钢轨滚动接触疲劳裂纹形态参数检测的研究具有重要意义。……