Piezoelectric coupling as a feature sensitive to structural alterations

The paper presents an exploratory study about the use of electro-mechanical coupling measurements as a feature for detecting structural alterations using piezoelectric transducers. This coupling between the piezoelectric transducers and the structure can be estimated by means of low frequency vibration measurements and will prove to be a feature sensitive to structure alterations and scarcely influenced by temperature variations. Moreover, the approach proposed is designed such that it can also employ piezoelectric elements already available in the system for other purposes (e.g., vibration control), thus not requiring any additional expensive device, and can work while the system to be monitored is operating. The paper introduces at first the principle of the method and shows how to improve its accuracy by connecting the piezoelectric transducers with proper electric impedances. Then, numerical simulations and experimental results are presented to prove the feasibility of the proposed approach.