Abstract
The baseline-free damage detection method of Lamb waves has the potential to obtain damage information efficiently in plate structures through damage scattering signals. However, the missing detection of damage occurs occasionally due to the angular scattering characteristic of Lamb waves. To solve this problem, a novel baseline-free damage detection approach based on path scanning at the detection region edges using mobile piezoelectric transducers is proposed herein. Several sensing points carrying separated damage scattering signals were picked out from the scanning paths. By removing the direct and boundary reflected signals, the damage signals were extracted and exported to a delay-and-sum imaging method to locate the damage. Two experiments with and without mobile transducers were conducted to validate the proposed method on an aluminum plate with artificially fabricated crack-like damage. The results show that the proposed baseline-free approach can locate the crack-like damage with high accuracy and efficiency and avoid potential loss of damage information. The proposed baseline-free method provides a novel and practical damage detection approach when considering the angular-dependent scattering characteristic of Lamb waves and can enhance the credibility of results in damage detection.
Highlights
A novel baseline-free approach based on mobile piezoelectric transducers is proposed to cope with the missing detection problem of damage caused by the angular scattering characteristic of Lamb waves
(4 where S(t) is the damage wave packet conta i0ne, d itn>thte2 received signal, La denotes the propagation distance of the wave directly from the actuator, Lb denotes the entire propagaantdio:n distance of the wave coming from the actuator and being reflected from the boundary, V denotes the velocity of the selected Lamb wave mode, ts represents the length of the exciting wave in the time domaint, a=ndLta1 a+ntd,t2 retpr=eseLnbt the end time of the direct
In the abovementioned scenario of damage detection based on path scanning, the mobile transducer was shifted around the paths and received signals at various locations with a uniform interval
Summary
Large-scale metal plates ubiquitously serve as crucial structural components in the aerospace, petroleum, mechanical and civil engineering industries [1–3]. Zheng et al [27] developed an integrated approach based on Lamb waves and electroimpedance in local and global damage detection on a plate, in which a mobile transducer set generated instantaneous baseline data. Another group of methods based on the reciprocity principle and time-reversal method have been studied and applied in conjunction with other techniques. A novel baseline-free approach based on mobile piezoelectric transducers is proposed to cope with the missing detection problem of damage caused by the angular scattering characteristic of Lamb waves. The experiment results are discussed and the conclusions are presented, along with the proposal of a strategy for practical inspections
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