An analysis of influencing factors for structural damage imaging using Lamb waves

Abstract

The use of Lamb waves for the inspection of large plate-like structures and their structural health monitoring (SHM) has been a topic of considerable interest in the development of advanced quantitative nondestructive evaluation techniques. Current interrogation algorithm using Lamb waves can roughly identify the location and severity of potential damages. It is well documented that Lamb waves may have multiple modes at a certain frequency, and accompanied by possible dispersion for each specific mode at different frequencies. In order to improve the accuracy of damage identification, some factors such as frequency, mode and cycle number of excitation signal must be taken into account. This paper presents a probability-based imaging approach for evaluating through-thickness hole damage in an aluminium plate. This method predicts the damage in terms of the probability of its occurrence at a certain spatial position of the structure. The influences of various factors on imaging results are analyzed. The results demonstrate that the imaging algorithm can be used to identify the location and severity of damage, but the identifying accuracy is highly related to frequency, mode and cycle number of exciting Lamb wave signal.