Electromechanical Impedance - Based Structural Health Monitoring Instrumentation System Applied to Aircraft Structures and Employing a Multiplexed Sensor Array

Abstract

ABSTRACT:The electromechanical impedance method has been seen as a promising tool for structural health monitoring regarding different types of structures and purposes. Most importantly, this method can be used in real-time applications. Frequently, massive, high-cost, single-channel impedance analyzers are used to process the time domain data, aiming at obtaining the complex, frequency-dependent electromechanical impedance functions and therefore infer about the presence, position and extent of an existing damage. However, for large structures, it is desirable to deploy an array of piezoelectric transducers over the area to be monitored and interrogate these transducers successively, in order to increase the probability of successful detection of damage at an early phase. The literature describes many miniaturized systems that can monitor large structures, however, presenting serious restrictions on data acquisition capabilities. This paper presents a hardware that is not limited to any data acquisition restriction, exhibiting an innovative way to measure the electromechanical impedance of multiplexed bonded transducers. Each logical block of the proposed architecture is presented in detail. The proposed system not only avoids costly fast Fourier transform analyzers/ algorithms, but also evades high-speed data acquisition hardware. A prototype using inexpensive integrated circuits and a digital signal processor was built and tested for two different types of structures: an aluminum beam and an aircraft aluminum panel. Simulated damages were introduced to each structure, and the detection performance of the prototype was tested. The actual prototype uses a universal serial bus connection to communicate with a personal computer.

Performance of three transducer mounting methods in impedance-based structural health monitoring applications

“…The measurement of the electrical impedance of the transducer may be performed using a commercial impedance analyzer. However, many researchers have proposed alternative measurement systems based on time-domain (Vieira Filho et al, 2011) or frequencydomain (Cortez et al, 2013;Kaur et al, 2016;Maruo et al, 2015) analysis. In this study, the electrical impedance was measured using the alternative system proposed by Baptista and Vieira Filho (2009), which is based on a multifunctional DAQ device controlled by a computer running appropriate software and drivers for the utilized DAQ model.…”

Monitoramento De Integridade Estrutural Baseado Em Impedância Eletromecânica Utilizando O Método De Krigagem Ordinária

“…Na técnica baseada em impedância eletromecânica (E/M), um elemento piezelétrico, geralmente um PZT (lead zirconate-titanate), é embutido ou anexado à estrutura por meio de uma cola adesiva de alta resistência e sujeito a uma tensão sinusoidal, de tal forma que o elemento piezelétrico retorna para um medidor a impedância eletromecânica, cujos resultados são plotados em função da frequência, resultando em um mapeamento das condições estruturais iniciais. Uma alteração nos valores de impedância eletromecânica revela a presença de danos na estrutura por meio da comparação entre as assinaturas da impedância inicial e após o dano (Maruo, Giachero, Steffen Junior, & Finzi Neto, 2015;Bhalla & Soh, 2012;Zagrai & Giurgiutiu, 2009).…”

Dressing Tool Condition Monitoring through Impedance-Based Sensors: Part 1—PZT Diaphragm Transducer Response and EMI Sensing Technique

“…Several research works have proposed alternative measurement systems based on the EMI technique [28,29,57,58]. In this paper, attention is given to the EMI technique proposed in [59] to measure the electrical impedance through a multifunctional data acquisition (DAQ) device.…”

“…On the other hand, piezoelectric lead zirconate titanate (PZT) diaphragm transducers have emerged as a potential sensing devices for structural health monitoring (SHM) applications based on the electromechanical impedance (EMI) principle [22,23,24,25,26,27,28,29,30]. In this way, many researchers have been proposed approaches based on piezoelectric EMI technique in frequency-domain (by exciting and sensing a PZT bonded to the structure to be monitored a suitable frequency range) [28,31,32] or time-domain (i.e. the voltage responses of PZT can reflect the health status of the monitored structure) [33,34,35] for detection and evaluation of damages in structural members of civil and aerospace engineering (such as: concrete and aircraft members), composite members and many others.…”