A damage index based on dynamic time warping for guided wave-based damage detection under temperature variation

Temperature variations have significant effects on the guided wave signals and therefore could cause false detection and limit the practical application for the guided wave-based damage detection. Many temperature compensation methods, such as baseline signal stretch methods, machine learning methods and data-driven methods have been developed. These methods either require a lot of data at different temperatures or are effective in some conditions. This could affect their application in practical engineering. In this study, a damage index based on dynamic time warping is presented, which can compensate the phase of current signal to the phase of baseline signal. Experiments were conducted on two stiffened composite panels to validate the effectiveness of the proposed method. The results show that the proposed method can effectively mitigate the temperature effect on the phase of guide wave signals, and can be applied to the actual damage detection under temperature variation.