粗糙表面铁磁性棒材微裂纹检测与信号处理技术研究

Detection of Micro-Cracks on Rusty Ferromagnetic Rod and Signal Analysis

为了克服微裂纹检测信号的重复性不能满足准确标定裂纹尺寸要求的缺陷 ,将重复测量所得微裂纹信号峰值视为带有噪声的连续峰值信号的采样值 ,利用小波变换在信号滤波上的优势对微裂纹峰值信号进行滤波后处理 ,由此确定被测裂纹的标准尺寸及其置信区间 ,从而使铁磁材料微裂纹检测技术从光洁表面向粗糙表面迈进了一步 .

Leakage magnetic field and special differential sensor are used to detect micro-cracks on the rough surface of ferromagnetic material. The detectable depth is about 0.8-1.6 mm with a wide of about 0.5 mm. Detection is hampered if the signal is not repeated. This shortcoming can be corrected by extracting the peak signals for every crack. The corresponding wavelets are used to determine reference crack and its believable district. The technique is first developed for cracks on a smooth surface and then adjustments are made for a rough surface.