Measurement and signal acquisition techniques from piezoelectric transducers excited with high frequency signals in the structural health monitoring

Abstract

The electrical impedance measurement of piezoelectric transducers is one of the most important steps in structural health monitoring systems with damage detection based on the Electromechanical Impedance (EMI) technique. It is a non-destructive technique in which, due to the piezoelectric effect, a relation is established between the mechanical properties of the monitored structure and the electrical impedance of the transducer, allowing structural damage to be detected by measuring and analyzing the electrical impedance. Therefore, the measurement system must be of quality to ensure good repetition between the impedance signatures within the frequency range sensitive to the damage. Many alternative measurement systems have been proposed to replace commercial impedance analyzers because they are most appropriate for field applications and multiple transducer measurements. Studies reported in the literature usually analyze the performance of these systems at low frequency. However, high frequency transducer excitation, typically above 1 MHz, allows detection of incipient damage, requiring the analysis of these measurement systems at high frequencies. Therefore, the aim of this doctoral research is to analyze the main techniques for measuring and acquiring signals from piezoelectric transducers excited with high frequency signals, above 1 MHz. The techniques will be analyzed and compared based on precision, accuracy, speed, energy consumption and performance in conditions of low signal-to-noise ratio. At the end of this research, it is expected to obtain a detailed study of the characteristics of the main techniques of measurement and signal acquisition from piezoelectric transducer, which can serve as a reference for the development of monitoring systems, resulting in the publication of articles in journals with selective editorial policy. (AU)