Volumetric imaging of defects through a non-planar surface
J McKee
One-dimensional (1D) phased arrays are widely used in NDT industries, but they have numerous limitations due to their element layout. Two-dimensional (2D) phased arrays have yet to become widely deployed in NDE industries, despite the many benefits they bring, such as volumetric imaging from a single array location and the potential for more defect information to be captured. In this work, a sparse 2D phased array is used to accurately image the interior of a specimen with a doubly-curved surface. A two-step imaging process using the total focusing method (TFM) algorithm is applied in order to firstly extract the non-planar surface geometry and subsequently image the interior of the specimen. As the footprint of the array is much smaller than the size of the specimen, the array is mechanically scanned across the surface with time-domain data collected at each location. The positioning of defects within the specimen is then compared to the true position using two metrics: the depth above the back wall and the lateral distance.
