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Proceedings Paper

Nondestructive testing and hardness measurement based on contact resonance of piezoelectric cantilevers (Conference Presentation)
Author(s): Faxin Li; Ji Fu

Paper Abstract

A suitable defect identification parameter is very important in the field of nondestructive testing (NDT). In this work, we proposed a NDT method which detects the sample’s local contact stiffness (LCS) based on the contact resonance of a piezoelectric cantilever. Firstly, through finite element analysis we showed that LCS is quite sensitive to typical defects including debonding, voids, cracks and inclusions, making it a good identification parameter. Secondly, a homemade NDT system containing a piezoelectric unimorph cantilever was assembled to detect the sample’s LCS by tracking the contact resonance frequency (CRF) of the cantilever-sample system based on strain signals. Testing results indicated that this NDT system could detect the above mentioned defects efficiently. The cantilever-stiffness dependent detection sensitivity was specially investigated and the stiffer cantilevers were found to be more sensitive to small defects. Then, a piezoelectric bimorph cantilever was fabricated and the electromechanical impedance, other than the strain signals, was measured to track the CRF of the cantilever-system. The LCS is then derived by using the equivalent-circuit model. The electromechanical impedance based NDT system is more compact and can be further developed to be a portable device. Finally, a Vicker indenter is fabricated onto the bimorph tip and the contact area is derived from the measured LCS. Thus the NDT system turns to be a hardness tester without any optical devices. It is very useful for in-situ testing or testing on inner surfaces where conventional hardness tester is not applicable.

Paper Details

Date Published: 22 June 2016
PDF: 1 pages
Proc. SPIE 9803, Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2016, 98032W (22 June 2016); doi: 10.1117/12.2218592
Show Author Affiliations
Faxin Li, Peking Univ. (China)
Ji Fu, Peking Univ. (China)

Published in SPIE Proceedings Vol. 9803:
Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2016
Jerome P. Lynch, Editor(s)

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