Localization of millimeter size defects in a steel hemispherical shell

摘要

Ultrasonic NDT is a commonly used modality for ensuring structural integrity. When the geometry of the structure in question is complex, challenges arise, especially for structures that curve upon themselves, such as pipes and spheres. One challenging case is the hemisphere, where edge reflections (such as occurring in plates) and multiple propagation paths (such as in spheres) add complexity to the task. We propose a contactless method based on laser ultrasound to generate guided waves on a 50 mm in diameter stainless-steel hemispherical shell. We studied samples featuring holes of various diameters and determined the detectability limit of our technique.