Laser ultrasonic defect localization using an omni-arrayed candle soot nanoparticle patch

The generation of ultrasonic surface waves with lasers has become a useful noncontact NDT&E tool. This laser ultrasound technique provides a very flexible and simple method for noncontact and remote generation of ultrasonic surface waves, and has the advantage that various wave shapes can be easily produced by changing the shape of the beam that is illuminating the target. In this work, a laser ultrasound NDT&E method is proposed for defect localization by incorporating an omni-arrayed patterned candle soot nanoparticles-polydimethylsiloxane (CSNP-PDMS) patch. The omni-arrayed CSNP-PDMS patch generates a surface wave with a selective range of frequency, and an omni-directional signal with high amplitude, which surpasses the limitation of the line-arrayed patch. Further, the arrival time algorithm was adopted to validate the effectiveness of the omni-directional patch for 2D damage detection, which in turn the maximum magnitude of contour mapping from calculation agrees well with the true defect location.