Surface Imaging Using Total Focusing Method on Surface Waves for Non Destructive Testing

Abstract

We demonstrate the effectiveness of total focusing methods (TFM) using Rayleigh waves for surface and sub-surface nondestructive inspection of different metals. The relatively low velocity of Rayleigh waves leads to sub-100 µm resolution imaging, with a penetration depth approximately equal to its wavelength. This allows for imaging and sizing sub-millimetric holes, possibly on coated material, as well as cracks, segregations, and other defects. The waves can propagate over long distances and works with curved surfaces or very close to edges. This shows potential for a new type of real-time surface inspection of large surfaces, with excellent spatial resolutions. The process is free of chemical preparation and cleaning, and can be fully automated, from acquisition to decision.

Keywords: corrosion, cracks, ultrasonic imaging, Rayleigh wave, phased-array