ABSTRACT

Detecting the debonding defects in the composite/rubber/rubber bonding structure is very difficult because of the high attenuation and aliasing of the ultrasonic wave from the structure. In order to solve this problem, a detection system was built based on the high-power ultrasonic pulse-echo method, and the time-frequency contour image of the wavelet coefficient modulus of the echo using wavelet transform was drawn. Through these, the characteristic parameters were clearly extracted which can represent the defects’ sizes and positions, and build the debonding defect parameter database. Based on this database, two defect evaluation algorithms are proposed and their accuracy is verified. Results show that the minimum Euclidean distance method can detect the defect diameter with an average deviation of 1 mm, a maximum deviation of 3 mm, and can realise accurate positioning of the testing defect. Based on the echo’s high attenuation and aliasing, this paper provides a solution for the ultrasonic detection of debonding defects in multi-layer structures,and verifies their feasibility and accuracy.

摘要

由于来自结构的超声波的高衰减和混叠，检测复合材料/橡胶/橡胶粘合结构中的脱粘缺陷非常困难。为解决这一问题，基于大功率超声脉冲回波法构建了检测系统，利用小波变换绘制了回波小波系数模的时频轮廓图。通过这些，可以清晰地提取出能够代表缺陷大小和位置的特征参数，并建立脱粘缺陷参数数据库。基于该数据库，提出了两种缺陷评价算法并验证了其准确性。结果表明，最小欧氏距离法可以检测出缺陷直径，平均偏差为1 mm，最大偏差为3 mm，并可实现检测缺陷的准确定位。基于回波的高衰减和混叠，本文为多层结构剥离缺陷的超声检测提供了一种解决方案，并验证了其可行性和准确性。