Affiliations: Federal University of Uberlandia, Campus Santa Monica,
Uberlandia-MG, Brazil | Department of Aerospace Engineering, University of
Michigan, MI, USA
Note: [] Corresponding author: L.V. Palomino, Federal University of
Uberlandia, Campus Santa Monica, Av. João Naves de Avila N. 2121, Bloco
1M, Uberlandia-MG, Brazil. Tel.: +55 3432394147; Fax: +55 3432394206; E-mail:
lvpalomino@mecainca.ufu.br
Abstract: Structural Health Monitoring (SHM) is the process of damage
identification in mechanical structures that encompasses four main phases:
damage detection, damage localization, damage extent evaluation and prognosis
of residual life. Among various existing SHM techniques, the one based on
electromechanical impedance measurements has been considered as one of the most
effective, especially in the identification of incipient damage. This method
measures the variation of the electromechanical impedance of the structure as
caused by the presence of damage by using piezoelectric transducers bonded on
the surface of the structure (or embedded into it). The most commonly used
smart material in the context of the present contribution is the lead zirconate
titanate (PZT). Through these piezoceramic sensor-actuators, the
electromechanical impedance, which is directly related to the mechanical
impedance of the structure, is obtained as a frequency domain dynamic response.
Based on the variation of the impedance signals, the presence of damage can be
detected. A particular damage metric can be used to quantify the damage. For
the success of the monitoring procedure, the measurement system should be
robust enough with respect to environmental influences from different sources,
in such a way that correct and reliable decisions can be made based on the
measurements. The environmental influences become more critical under certain
circumstances, especially in aerospace applications, in which extreme
conditions are frequently encountered. In this paper, the influence of
electromagnetic radiation, temperature and pressure variations, and ionic
environment have been examined in laboratory. In this context, the major
concern is to determine if the impedance responses are affected by these
influences. In addition, the sensitivity of the method with respect to the
shape of the PZT patches is evaluated. Conclusions are drawn regarding the
monitoring efficiency, stability and precision.
Keywords: Structural health monitoring, damage detection, piezoceramic sensor-actuators
