Application of laser ultrasonic technique for detecting weld defect based on FDST method

Abstract The propagation image of laser-generated ultrasonic wave interaction with the weld defect are investigated by the finite element method (FEM) and experimental system. We analyses the changes of ultrasonic wave at the different positions from weld defect in detail. Then analyses the frequency changes of ultrasonic wave at different source-receiver distance based on FDST (fast discrete sine transform). In order to quantitative detect weld defect, we compare the different spectrum images of laser-generated ultrasonic wave based on FFT (fast frequency transform) with the different spectrum images of laser-generated ultrasonic wave based on FDST, which demonstrates the FDST analysis of the spectrum images method can be intuitive, efficient detection of weld defect.