Structural damage detection in noisy environments based on the electromechanical impedance and Lamb waves with piezoelectric transducers excited with high frequency signals

Abstract

Piezoelectric transducers are used in many applications and, in recent years, the use of these transducers in non-destructive techniques for structural damage detection has grown. These techniques allow the detection of incipient damage in various types of structures under a minimally invasive condition and are, therefore, extensively investigated for Structural Health Monitoring (SHM) applications. Some of the most known non-destructive techniques using piezoelectric transducers are the Electromechanical Impedance (EMI) technique, which has as principle the relationship between the electrical impedance of the transducer and the mechanical impedance of the monitored structure, and the Lamb wave technique, which is based on the propagation of a guided wave between an actuator transducer and a sensor transducer. Both techniques use an actuator transducer that promotes a forced excitation of the monitored structure and this research aims to analyze and compare the two techniques with the actuator transducer excited with high frequency signals, focusing on the application in noisy environments, which is the condition typically found in actual applications. The two techniques will have their performances evaluated for sensitivity to structural damage and noise effects, which will be generated using a transducer fixed in the structure and excited with several types of noise of different intensities. It is expected to obtain at the end of this research a detailed study of the behavior of the two methods of damage detection with high frequency excitation signals and under noise effects, which can be a good reference for the development of SHM systems. (AU)