﻿ 钢轨裂纹深度对脉冲涡流热成像的影响

# 钢轨裂纹深度对脉冲涡流热成像的影响Influence of Depth on Eddy Current Pulsed Thermography for Rail Crack Detection

Abstract: 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.

1. 引言

2. 方法

2.1. 感应加热原理

$e=-\frac{\text{d}\varphi }{\text{d}t}$ (1)

$Q={Ι}^{2}Rt$ (2)

2.2. 有限元仿真建模及参数设置

COMSOL Multiphysics是以有限元法为基础，通过求解偏微分方程(单场)或偏微分方程组(多场)来实现真实物理现象的仿真。

2.3. 实验系统设置

2.4. 试样的获取

Figure 1. System of eddy current pulsed thermography

Figure 2. Artificial defects rail specimen

Figure 3. The distributions of rail cracks

Table 1. The size descriptions of rail cracks

3. 结果和讨论

3.1. 垂直裂纹仿真和实验对比

3.1.1. 不同深度表面垂直裂纹的仿真分析

3.1.2. 不同深度表面斜裂纹的仿真分析

Table 2. The surface temperature distributions of vertical crack at different depths

Table 3. The surface temperature distributions of oblique crack at different depths

3.2. 斜裂纹仿真与实验对比

3.2.1. 不同深度有限长垂直裂纹检测

3.2.2. 不同深度斜裂纹检测

(a) (b)

Figure 4. Finite length cracks at different depths in single frame images

Table 4. The single frame images of oblique cracks with different depths

4. 总结

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[7] 梅林, 陈自强, 王裕文, 等. 脉冲加热红外热成像无损检测的有限元模拟及分析[J]. 西南交通大学学报, 2000, 34(1): 66-69.

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