Qualitative impedance-based health monitoring of civil infrastructures

Abstract

This paper presents a qualitative health monitoring technique to be used in real-time damage evaluation of civil infrastructures such as bridge joints. The basic principle of the technique is to monitor the structural mechanical impedance which will be changed by the presence of structural damage. The mechanical impedance variations are monitored by measuring the electrical impedance of a bonded piezoelectric actuator/sensor patch. This mechanical-electrical impedance relation is due to the electromechanical coupling property of piezoelectric materials. This health monitoring technique can be easily adapted to existing structures, since only a small PZT patch is needed, giving the structure the ability to constantly monitor its own structural integrity. This impedance-based method operates at high frequencies (above 50 kHz), which enables it to detect incipient-type damage and is not confused by normal operating conditions, vibrations, changes in the structure or changes in the host external body. This health monitoring technique has been applied successfully to a variety of light structures. However, the usefulness of the technique for massive structures needs to be verified experimentally. For this purpose, a 500 lb quarter-scale deck truss bridge joint was built and used in this experimental investigation. The localized sensing area is still observed, but the impedance variations due to incipient damage are slightly different. Nevertheless, by converting the impedance measurements into a scalar damage index, the real-time implementation of the impedance-based technique has been proven feasible.

Structural Health Monitoring for Composite Materials

“…However, direct measurement for the mechanical impendence is very hard. With PZT transducers, mechanical impendence is indirectly measured as E/M one for damage detection in E/M impedance method [38].…”

“…Note that the impedance measurement is often performed in ultrasonic frequency range. At such high frequencies, the dynamic response is dominated in local modes and the excitation wavelength is small enough to ensure the high sensitivity to incipient local flaws [38][39][40].…”

Damage assessment in concrete structures using piezoelectric based sensors

“…By comparing the impedance signature taken in the pristine state and at any other time, structural damage can be determined. Generally, both frequency and amplitude shifts are produced relative to the pristine state (without damage) (Ayres et al, 1998;Chaudhry et al, 1995;Sun et al, 1995;Park et al, 2000;Zagrai and Giurgiutiu, 2001;Giurgiutiu et al, 2002Giurgiutiu et al, , 2004Peairs et al, 2004;Narayanan and Subramaniam, 2016a). Application of EMI technique for damage detection in concrete structures requires a careful study of the changing compliance of the substrate for different forms of damage in the substrate material from the incipient to the visible stages.…”

Impedance-based structural health monitoring for composite laminates in cryogenic environments

“…The electromechanical impedance approach using smart piezoelectric ceramic transducers having selfactuating and sensing capabilities has shown potential applications in damage detection in structural systems. Sun et al [4] and later Ayres et al [1] reported the use of piezoelectric ceramic patches (PZT) for damage detection and characterization on a laboratory-size truss structure and a prototype truss joint, respectively. The damage detection method is based on the principle of electro-mechanical coupling between the host structure and the bonded PZT patch.…”