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.
Highlights
Structural Health Monitoring (SHM) techniques have been lately receiving great interest from the academic and industry communities that are interested in aerospace and civil structures, vehicles and machines [1]
This work presents a preliminary study of the influence of the shape of the PZT patch on the impedance measurement; the influences of electromagnetic radiation, temperature and pressure, and ionic environment on the impedance-based structural health monitoring method are analyzed
The technique known as impedance-based structural health monitoring uses the piezoelectric properties of the PZT patch that is installed in the structure being tested and is considered as a non-destructive damage evaluation method [2]
Summary
SHM techniques have been lately receiving great interest from the academic and industry communities that are interested in aerospace and civil structures, vehicles and machines [1]. It is a nondestructive method that explores the electro-mechanical coupling property of piezoelectric materials to monitor the occurrence and evolution of structural damage. The application of this technique consists in bonding piezoelectric materials, more frequently in the form of thin patches, to the monitored structure. Through the variations observed in the electromechanical impedance responses, it is possible to assess information about structural changes induced by damage This possibility is related to the electrical impedance of the PZT patch being directly associated with the mechanical impedance of. This work presents a preliminary study of the influence of the shape of the PZT patch on the impedance measurement; the influences of electromagnetic radiation, temperature and pressure, and ionic environment on the impedance-based structural health monitoring method are analyzed
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