脉冲反转和小波变换在非线性超声检测中的应用

Application of Pulse- Inversion Technique and Wavelet Transform for Nonlinear Ultrasonic Nondestructive Testing

为提高非线性超声检测技术的准确性和鲁棒性,文中将脉冲反转技术和信号小波系数相关性滤波算法结合用于处理非线性超声检测信号。利用脉冲反转技术抑制实验仪器产生的奇数次谐波信号,再根据信号小波系数相关性算法滤除噪声。实验结果表明:上述信号处理方法能有效提取频率纯净的二次谐波,提高了超声非线性系数表征试件粘接强度的能力。

Based on correlation of the multi-level wavelet coefficients,a new algorithm combined with pulse- inversion technique was proposed to improve the accuracy and robustness of defects for nonlinear ultrasonic nondestructive testing. The pulse-inversion technique was used to inhibit the odd harmonics due to nonlinearity of the input instrumentation. By employing the wavelet transform method,adhesive joints tested ultrasonic signal were de-noising processed. The experimental results show that proposed method can efficiently extract the pure second harmonic and enhance ability to characterize the adhesive strength by ultrasonic nonlinear coefficient.