Extended Non-Stationary Phase-Shift Migration for Ultrasonic Imaging of Irregular Surface Component

Abstract

This paper introduces an extended non-stationary phase-shift migration (ENSPS) method for ultrasound imaging of irregular surface components. This method extends non-stationary phase-shift (NSPS) technology based on the classical B-scan data to full-matrix capture (FMC) data. In addition, a new surface estimation method (SEM) is also proposed to prepare for ultrasonic imaging of irregular surface components. The method is implemented in the frequency domain, thereby ensuring the computational efficiency. In the numerical simulation, two components with different surface shapes were simulated to study the imaging ability of the method for hole defects and upper surface crack defects in irregular surface components. The simulation results show that the proposed ENSPS can detect hole defects with an interval of 0.5 mm and vertical surface cracks. In order to verify the simulation results, we set up a water-immersed ultrasonic experiment platform and obtained the ENSPS images. As a comparison, the extended phase-shift-plus-interpolation method (EPSPI) is also used to process the same data. The comparison results show that the algorithm proposed in this paper has the advantages of high resolution and low noise for the ultrasonic imaging of irregular surface components.