Motion magnification-based nonlinear ultrasonic signal enhancement and its application to remaining fatigue life estimation of a steel padeye

Abstract

In this study, a nonlinear ultrasonic signal enhancement method based on phase-based motion magnification was proposed. First, a two-dimensional (2D) video was constructed from a onedimensional time-domain ultrasonic signal with an automatically selected pixel scale. The constructed 2D video was spatially decomposed into multiple sub-bands with different spatial scales. The subtle motions of the nonlinear responses of interest were enhanced by phase denoising and magnification in each sub-band. Then, the magnified 2D video was reconstructed by collapsing all the amplified sub-bands. Finally, a magnified ultrasonic signal was extracted from the magnified 2D video for further nonlinear ultrasonic analysis. The proposed method was validated with a group of synthetic signals at different noise levels, and applied in the estimation of the remaining fatigue life of a steel padeye with improved accuracy.