基于脉冲压缩技术的相邻缺陷识别方法研究

Study on identification method of adjacent defects using pulse compression technique

超声成像技术可以为探伤人员提供更可靠、直观的检测结果,在超声无损检测中的应用越来越普遍。然而,超声检测信号的时间宽度较宽,时间分辨率较低,在两缺陷相距较近的情况下,缺陷的反射回波往往叠加在一起,使得超声成像时难以实现相邻缺陷的辨识。为提高超声波检测信号时间分辨率,实现相邻缺陷的识别,将维纳滤波和自回归谱技术相结合,发展了一种超声脉冲压缩技术,并将其应用于超声阵列成像处理。研究了自回归谱分析中回归阶数和衰减窗宽度对缺陷识别效果的影响,并优化出最佳的处理参数。仿真和检测实验结果表明,通过对超声检测信号进行维纳滤波和自回归谱分析,可以大大提高超声检测信号的时间分辨率,从而实现相邻缺陷的识别。

Ultrasonic imaging technique can provide more intuitive and reliable detection results for detection personnel, and is widely used in ultrasonic nondestructive testing. However, the ultrasonic detection signal has wide time width and the time-resolution is low. When two defects are adjacent in distance, the echoes from the two defects are overlapped; it is difficult to identify the adjacent defects in ultrasonic imaging. In order to increase the time resolution of ultrasonic detection signal and achieve adjacent defect identification, a pulse compression technique was developed and applied in ultrasonic array imaging, which combines Wiener filtering and autoregressive spectral analysis techniques, and the identification of adjacent defects can be achieved. The influence of the autoregressive order and the attenuation window width on defect identification result in autoregressive spectral analysis was studied; and the optimum parameters were obtained. Simulation and detection experiment results show that the proposed technique can greatly improve the time resolution of the ultrasonic detection signal and achieve adjacent defect identification.