An Integrated Health Monitoring Technique Using Structural Impedance Sensors

Abstract

This paper presents an integrated methodology to detect and locate structural damage. Two different damage detection schemes are combined in this methodology, which involves utilizing the electromechanical coupling property of piezoelectric materials and tracking the changes in the frequency response function data, respectively. Physical changes in the structure cause changes in mechanical impedance. Due to the electromechanical coupling in piezoelectric materials, this change in structural mechanical impedance causes a change in the electrical impedance of the piezoelectric sensor. Hence, by monitoring the electrical impedance one can qualitatively determine when structural damage has occurred or is imminent. Based on the fact that damage produces local dynamic changes, this technique utilizes a high frequency structural excitation (typically greater than 30 kHz) through the surface-bonded piezoelectric sensor/actuators. As a second step, a newly developed model-based technique, using a wave propagation approach, has been used to quantitatively assess the state of structures. Direct frequency response function data, as opposed to modal data, are utilized to characterize the damage in the structures. A numerical example and an experimental investigation of one-dimensional structures are presented to illustrate the performance of this technique.

Damage Detection in Thin Plates and Aerospace Structures with the Electro-Mechanical Impedance Method

“…Further model development was attempted by Zhou et al [9] and Esteban [10], but they did not derive explicit expressions for predicting the E/M impedance as it would be measured by the impedance analyzer at the terminals of a structurally attached PWAS. Park et al [11] performed the axial vibrations analysis of a bar, but did not consider the flexural response, or the sensor dynamics. Giurgiutiu and Zagrai [12] derived an expression for the E/M admittance and impedance that incorporates both the sensor dynamics and the structural dynamics.…”

Piezoelectric Wafer Embedded Active Sensors for Aging Aircraft Structural Health Monitoring

“…The name ElectroMechanical (E/M) Impedance Method was first used by Giurgiutiu and Rogers (1997). Novel ways to interpret the E/M impedance spectra and identify structural damage have been explored by Quin et al (1999), Lopez et al (2000); Park et al (2000b), Tseng et al (2000), Monaco et al (2001). The essence of the E/M impedance method is illustrated in Figure 1.…”

Técnicas avançadas de normalização de dados aplicadas ao método de monitoramento de integridade estrutural baseado em impedância eletromecânica

“…O desenvolvimento teórico que propôs o uso da impedância como técnica para monitoramento estrutural foi inicialmente proposto por Liang; Sun; Rogers (1994) e posteriormente ampliado por Chaudhry et al ( , 1996, , Park et al (1999a), Park;Inman(1999bInman( , 2000aInman( , 2000bInman( , 2001); Park et al (2003), Giurgiutiu e Zagrai (2000, 2002, Bao (2002), Giurgiutiu et al (2003), Soh et al (2000), Bhalla; Naidu; , Bhalla et al (2002) O modelo que quantifica e descreve o processo de medição é visto na Figura 2.1 para um sistema de 1 g.d.l. As cerâmicas de PZT cujo tamanho é usualmente menor que 25x25x0,1mm, são coladas na estrutura a ser monitorada por meio de um adesivo de alta rigidez, podendo ser uma cola instantânea ou uma resina de epóxi, para garantir uma melhor interação mecânica.…”

“…Isso porque a magnitude da resposta é muito maior, quando comparada com a da ressonância da estrutura. (Park et al, 2000b).…”