噪声对管道超声纵向导波损伤检测的影响

在管道超声导波检测技术的基础上,对不同程度纵向缺陷的损伤检测进行了数值模拟.利用缺陷反射信号对损伤的定位,通过改变管壁局部刚度,研究了缺陷反射信号强度变化的相关规律以及超声导波对缺陷的敏感度,分析了噪声信号对损伤识别的影响,并利用小波的分解和重构算法将信噪分离.结果表明不同程度的信噪比会对超声导波检测法造成一定的影响,通过低通滤噪的方法对信号进行信噪分离,可实现高噪条件下的损伤检测.

Noise Effect on Defect Identification in Pipes by Ultrasonic Longitudinal Guided-Wave

A defect identification in pipes by ultrasonic longitudinal guided-wave is proposed. The numerical damage detection signals of the pipe are derived by LS-DYNA, involving the reduced stiffness of elements on the defect location. Furthermore, Wavelet transform is adopted to identify the imperceptibility defect. By means of reflection signal peak intensity, the sensitivity of the proposed approach versus the change of local stiffness in pipe wall is evaluated. The effect of noise on the identified results is also discussed. Defect identification in the low signal-noise ratio is realized based on the algorithm of wavelet decomposition and reconstruction.