Numerical Study on Ultrasonic Wave Scattering of Rough Finite-Size Cracks

Natural defects, unlike artificial defects, inevitably have rough surfaces. With high roughness, ultrasonic scattering occurs, and the response amplitude decreases; with low roughness, a high-response signal can be obtained. If the scattering of rough defects is predicted, the results can be useful for increasing the defect detection rate using an inspection method based on the scattering information. Previous studies on rough surfaces were mainly focused on the roughness of an infinite plane, but it is difficult to apply such a method to nondestructive inspection in detecting actual finite-size defects. In this study, a numerical analysis of ultrasonic scattering was performed in an actual ultrasonic inspection environment to evaluate smooth and rough defects, and each feature was analyzed and compared. It was found that the ultrasonic response of finite rough defects was higher than that of the infinite rough surface, and the results were compared with the ultrasonic response on the smooth defect. This method can be implemented to increase the probability of defect detection through ultrasonic nondestructive testing.