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超声导波阵列检测技术可以实现板类结构的快速、大面积检测,是工业领域中最有前景的技术之一。针对目前此技术中存在的单一模态传感器难制作、检测频率高(一般在200 kHz以上)、需非常密集的传感器阵列和成像分辨率低等问题,本文采用一种圆环形线圈EMAT(Electromagnetic Acoustic Transducer),在较低频率15 kHz激励产生单一A0模态Lamb波,由8个传感器组成环形阵列,利用TFM(Total Focus Method)进行成像,实现了超声Lamb波对板类结构的快速、大面积检测。对一块包含直径为27 mm通孔的3 mm厚铝板进行实验研究,结果表明,此系统具有较高的测量稳定性和成像分辨率,能快速定位缺陷,适用于对板类结构进行大面积粗检。在对检测系统盲区形成原因分析的基础上,建立了一种计算盲区范围的方法。
Ultrasonic guided wave array detection technology can achieve rapid detection of plate structure, large area detection, is one of the most promising technology in the industrial field. In order to solve the problem that single modality sensor in this technology is difficult to manufacture, high detection frequency (usually above 200 kHz), very dense sensor array and low imaging resolution, a circular coil EMAT Acoustic Transducer), a single mode A0 mode Lamb wave is generated at a lower frequency of 15 kHz excitation, a ring array is composed of 8 sensors, and an imaging is performed by using a TFM (Total Focus Method), so that a fast, large Area detection. An experimental study on a 3 mm thick aluminum plate with a 27 mm diameter through hole showed that the system has high measurement stability and imaging resolution and can rapidly locate defects and is suitable for large area coarse Check Based on the analysis of the causes of the detection system blind area, a method of calculating the blind area was established.