基于视觉位感条纹的转轴裂纹缺陷检测

裂纹缺陷是转轴系统中常见的故障形式，裂纹的呼吸效应会改变转轴的动态特性，使转轴的径向振动信号中出现倍频分量。提出一种基于单目视觉位感条纹振动测量原理的转轴裂纹缺陷检测新方法，可实现转轴振动信号的高效测量和裂纹缺陷的快速检测。分析了含裂纹转轴系统的动力学方程，并系统描述了单目相机成像条件下采用位感条纹图案实现转轴径向二维振动测量的原理，建立了成像位感条纹动态编码参数与转轴径向振动位移之间的数学模型。通过与传统基于两路电涡流传感器测量系统的试验对比分析，验证了本方法测量结果的精确性。分析转轴系统在不同转速下径向振动中的频率分量，当转速接近1/2临界转速时，2倍频信号非常明显，且其幅值接近转频幅值，可实现对于转轴系统中裂纹缺陷的有效检测。

Vision-based Displacement-sensitive Fringe Pattern for Identification of Crack in Rotating Shaft

Crack defect is a common failure form in rotating shaft. The breathing effect of crack defect will change the dynamic characteristics of rotating shaft and cause multiple frequency components in the radial displacement. A novel identification method using visual displacement-sensitive fringe pattern (DSFP) is proposed to determine the existence of transverse crack in rotating shaft. It can realize the efficient measurement of vibration signal and the rapid detection of the shaft crack defect. The dynamic equation of the cracked shaft and the measurement principle for the shaft radial two dimensional vibration using single camera and one DSFP are illustrated in detail. The mathematical relationship between the dynamic encoding parameters in the imaging DSFP and the real shaft radial displacement is established. The measuring results obtained both from the proposed system and the traditional two eddy current sensors based system verify the measurement accuracy of the proposed system. The multiple frequency components in the radial displacement of cracked shaft at different speeds are analyzed. When the rotation speed is close to half of critical rotation speed, the double frequency component is obvious and its amplitude is close to the rotation frequency amplitude, which can realize the effective detection of crack defect in rotating shaft system.