Elastic waves interference for the analysis of disbonds in single lap joints

•Elastic waves interference is proposed as a novel SHM method.•A single lap joint made of two thin plates bonded over an assigned area was tested.•Interference between generated and reflected signals can be constructive or destructive depending on the status of the joint.•A debonding length (deb) ca...

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Bibliographic Details
Published in:Mechanical systems and signal processing 2019-08, Vol.128, p.340-351
Main Authors: Nicassio, F., Carrino, S., Scarselli, G.
Format: Article
Language:English
Subjects:
Adhesion
Adhesive joints
Bonded joints
Computer simulation
Debonding
Disbonds
Elastic waves
Interference
Lamb waves
Lap joints
Reflected waves
SHM
Structural Health Monitoring
Wave propagation
Wave reflection
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Summary:•Elastic waves interference is proposed as a novel SHM method.•A single lap joint made of two thin plates bonded over an assigned area was tested.•Interference between generated and reflected signals can be constructive or destructive depending on the status of the joint.•A debonding length (deb) can be uniquely related to a specific attenuation frequency.•Destructive interference for health monitoring of single lap joints is novel and the approach is baseline-free. In the present paper a method for the Structural Health Monitoring (SHM) of bonded lap joints is presented. This method is based on the interference of elastic waves generated by piezo sensors and travelling along thin bonded plates through the adhesion area. Tone bursts of different extension were generated and, when they encountered the debonded area, the wave speed changed. This affected the wave reflection at the boundary of the disbond and the subsequent interference of the reflected wave with the main wave travelling along the joint. Destructive interference conditions were promoted when the adhesive was partially debonded and this was related to the length of the disbond. In the present study numerical simulations based on finite elements were performed and compared with a simplified analytical model describing the Lamb waves propagation through the joint. The simulation results were subsequently compared with the experimental data and a good agreement was found: the proposed method was simple, straightforward and its application on thin single lap joints provided reliable results.
ISSN:0888-3270
1096-1216
DOI:10.1016/j.ymssp.2019.04.011