Lamb Wave Detection of Delaminations in Large Diameter Pipe Coatings

Abstract

This paper describes combined experiments and simulations to automate the extraction of ultrasonic guided wave mode arrivals in order to gain quantitative information about large-diameter pipeline coatings. The dynamic wavelet fingerprint technique (DWFT) is used to show differences between unknown coatings as well as to identify the presence of delamination and grinding flaws within the Lamb wave propagation path. Combined with complex multi-layered models to help interpret the guided wave feature changes, this extraction algorithm can be used for the detection of hidden flaws under a variety of protective coatings without having to disturb the coating or pipeline flow. High-resolution supercomputer simulations are developed using the elastodynamic finite integration technique (EFIT) accounting for the 3D interaction of realistic Lamb wave beams with finite-sized coating delaminations.