Inspecting integrity and residual stress of plate by ultrasonic wave

Ultrasonic tomography and critically refracted longitudinal (LCR) wave method is studied for inspecting the integrity and residual stress of plate. A transducer array based on sixteen elements is employed to imaging the corrosion defect for evaluating the size of defect quantitatively. The central frequency of element is chosen as 1MHz to excite low mode lamb wave. The algebraic reconstruction technique (ART) and simultaneous iterative reconstruction technique (SIRT) by attenuation of Lamb wave signal are used to get the projection data for tomographic reconstruction. The reconstructed image indicates that ultrasonic tomography is efficient to evaluate the integrity of plate. The residual stresses inspecting is based on the effect of stresses on the propagation velocity of elastic waves. The LCR wave mode was employed and accurate travel time data were measured for plate of steel. According to the results of experiments, the active LCR wave will effectively interact with the internal stress within a defined depth range and generate a measurable change on the travel time.