基于涡流热成像的铁磁材料近表面微裂纹检测

采用涡流热成像技术，对铁磁材料近表面微裂纹进行了检测研究。提出了平行激励热传导方式检测近表面微裂纹的检测方法；数值计算模拟了涡流激励下裂纹处的生热过程，分析了裂纹处的温度分布及其对检测结果的影响；采用平行激励方式对含近表面微裂纹的铁磁材料进行了检测实验，通过提取试件表面温度分布数据，获取其变化速率曲线，实现了对裂纹的检测和识别。结果表明:涡流热成像平行激励方式能够准确地检测到铁磁材料近表面的微裂纹缺陷；选择适当的涡流激励时间有助于提高裂纹处与非裂纹处温度对比，增强检测效果。该方法的研究为近表面微裂纹的检测和定量识别奠定了基础。

Micro crack detection near surface of ferromagnetic materials based on eddy current thermography

Eddy current thermography technique was adopted to detect micro cracks near surface of ferromagnetic materials. The method of parallel excitation and heat conduction was put forward to detect micro cracks near surface. The process of heating in cracks using eddy current thermography was simulated by numerical calculation. The temperature distribution around the crack and the influence on the detection results were analyzed. The parallel excitation was adopted for the detection test. The surface temperature distribution curve of the specimen was extracted, and the slope curve was got by differential. Finally, the detection and recognition on cracks were realized. The results show that the parallel excitation method of eddy current thermography can have an efficient detection on micro cracks near surface of ferromagnetic materials, and appropriate excitation time can contribute to the rise of the temperature contrast and the enhancement of the testing effect. All the above researches lay a foundation for the detection and quantitative identification of micro cracks near surface.