钢轨裂纹深度对脉冲涡流热成像的影响

Abstract

我国高铁的快速发展对钢轨裂纹的巡检提出了越来越高的要求，基于电、磁、热等多物理场耦合的脉冲涡流热成像(ECPT)技术，可实现对钢轨表面裂纹的非接触、快速检测，对保障高铁安全运行意义重大。相对于表面裂纹长度和宽度，裂纹侵彻深度和侵入角度更加隐蔽，也更加难以检出和区分。本文通过电磁感应加热有限元仿真和钢轨表面人工裂纹检测实验，对比研究了垂直裂纹侵彻深度和斜裂纹侵入角度对钢轨表面热分布的影响，及其红外成像的区别。研究表明垂直裂纹侵彻深度超过1 mm时，高温区由励磁线圈附近趋向于裂纹两个顶端；斜裂纹则当侵彻深度超过2 mm时高温区发生迁移，且高温区沿裂纹非对称分布。因此，根据高温区分布位置及形状可实现多种类型钢轨表面裂纹的检测与识别。 The demand of rail track inspection is increasing with the development of high speed railway in China. The surface cracks of track can be detected non-destructively and fleetly by eddy current pulsed thermography (ECPT) technology, based on multi-physics such as electricity, magnetism and thermography. This technology is important to high speed railway security. Comparing with the length and width of surface crack, depth of vertical crack and angle of lean crack are hard to be detected and classified. By finite element simulation and artificial track crack inspection, this paper proposes the difference of IR images and the influence of vertical crack depth and lean crack angle on heat distribution. The results indicate that high temperature regions move to the ends of crack when the crack depth exceeds 1 mm. For lean cracks, high temperature regions distribute asym-metrically along cracks and move when the depth increases more than 2 mm. Therefore, different surface track cracks can be detected and classified by the shape and distribution of high tempera-ture regions.