探头位置对玻璃钢抽油杆检测缺陷信号的影响

Influence of the Position of Probe on Detection Singal in the Microwave Nondestructive Examination of Glass Reinforced Plastic Sucker Rod

利用微波对玻璃钢抽油杆模拟缺陷进行无损检测 ,在信号源功率、频率以及发射探头和穿透接收探头形式确定的前提下 ,改变穿透接收探头与被测试件之间的相对位置对于缺陷信号的灵敏度、分辨率有很大的影响 .在采用双通道检测时 ,穿透接收探头处于与被测试件 80～ 1 40 mm位置对缺陷信号的反映程度与其处于 1～ 2 0 mm位置有明显的区别 :反射信号波没有明显的变化 ,而穿透法所反映的信号波却发生了很大变化 ,缺陷处信号波部分成为封闭的矩形条 ,矩形条的高度相同 ,宽度不同 .矩形条的宽度是缺陷实际大小的综合反映 ,与穿透探头处于 1～ 2 0 mm相比 ,有无缺陷一目了然且便于计算机识别 .

When the power and frequency of singnal source, transmitting probe and receiving transducer are determined, the signals of defects were tested under different distances between penetrating receiving transducer and test piece by means of two-channel testing system. The results show that, compared with the distance of 1~20mm, when the distance is 80~140mm, the sensitivity and distinguishability of the penetrating receiving signal are all improved, but there is not clear change of the reflecting signal. At defects, the receiving signal becomes some closed rectangles. The heights of the closed rectangles are the same, but their widthes are different. The widthes reflect the different sizes of the defects. This waveshape of the receiving signal makes a computer very easely identify the defects and determine their sizes.