A Method of Defect Characterization in Guided Wave Testing Using Persistent Homology

Guided wave based non-destructive testing technique has been widely used in many engineering structures. Accurate characterization of defects by extracting defect-related features from the guided wave testing signals is very important for the condition evaluation of the tested specimen. In this paper, a topological feature for defect characterization is extracted from the topological domain of the guided wave testing signal. Specifically, the topological feature is extracted from the 2-dimensional phase space of the testing signal based on persistent homology. The steel wire notch experiments show that there is an exponential relationship between the topological feature and the cross sectional area loss ratio of the steel wire, and the goodness of fit is 0.9962. This paper confirmed that the persistent homology is a useful tool to analyze guided wave testing signals to investigate the defect characterization.