旋转磁场激励下激光焊接裂纹磁光成像规律研究

为了研究旋转磁场激励下焊接裂纹磁光成像规律，采用工频旋转磁场对焊接裂纹激励并由磁光传感器获取裂纹磁光图像的方法，进行了理论分析和实验验证，取得了工频旋转磁场不同励磁强度下的动态磁光图像。结合磁光成像原理和旋转磁场理论，对所获数据的灰度值进行了对比分析。结果表明，旋转磁场工频励磁下任意1帧磁光图随励磁时间的推移都会发生变化，并以初始3帧磁光图为一个循环周期依次向下一帧磁光图转换，经过885帧磁光图后回到初始状态。该规律的发现有利于减少有效励磁时间，提高焊接缺陷无损检测效果。

Study on magneto-optical imaging law of laser welded crack under the excitation of rotating magnetic field

In order to study magneto-optical imaging (MOI) law of weld cracks under the excitation of rotating magnetic field, the method of using rotating magneto magnetic field to stimulate weld cracks and acquiring magneto-optical images of cracks by a magneto-optical sensor was used. Theoretical analysis and experimental verification were carried out. The dynamic magneto-optical images under different excitation intensities of rotating magnetic field were obtained. According to the principle of magneto-optical imaging and the theory of rotating magnetic field, the gray value of the obtained data was compared and analyzed. Experimental results show that, under the power frequency excitation of rotating magnetic field, any frame of magneto-optical images will change with the going of excitation time. Taking original three frames as a cycle, each frame of magneto-optical images converts to next frame magneto-optical image in turn. It returns to the initial state after 885 frames of magneto-optical images. The discovery of this law is beneficial to reduce the effective excitation time and improve the effect of non-destructive testing of weld defects.