Truss Structure Integrity Identification Using PZT Sensor-Actuator

Abstract

This paper presents a frequency domain impedance-signature-based technique for health monitoring of an assembled truss structure. Unlike conventional modal analysis approaches, the technique uses piezoceramic (PZT) elements as integrated sensor-actuators for acquisition of signature pattern of the truss. The concept of the localization of sensing/actuation area for damage detection of an assembled structure is presented for the first time. Through a PZT patch bonded to a truss node and the measurement of its electric admittance, which is coupled with the mechanical impedance of the truss, the signature pattern of a truss is monitored. The admittance of a truss in question is compared with that of the original healthy truss. Statistic algorithm is then applied to extract a damage index of the truss based on the signature pattern difference. Experimental proof that over a selected band, the detection range of a bonded PZT sensor on a truss is highly constrained to its immediate neighborhood is presented. This characteristic allows accurate determination of the damage location in a complex real-world structure with a minimum mathematical modeling and numerical computation.

Design and Analysis of Advanced Materials in a Thermal/Acoustic Environment. Delivery Order 0007: Volume 1 - Structural Health Monitoring

“…These early works demonstrated that a permanently attached PWAS can be used as a structural-identification sensor since the PWAS terminals reflect the coupled-system dynamics. The E/M impedance method was first used for SHM to detect damage in a truss structure by Sun, et al [47]. It was first shown to have extreme sensitivity to local damage and insensitivity to far-field damage in the tail section of a Piper Model 601P airplane [48].…”

Pipeline Structural Health Monitoring Using Macro-fiber Composite Active Sensors

“…Therefore, the real part of the electrical impedance is commonly used for SHM applications. (Sun, et al 1995) For SHM applications, impedance methods are similar to traditional vibrations techniques in that both methods aim to monitor the structural integrity of a structure by observing changes in its characteristic vibrations over time. An extensive review of SHM techniques based upon traditional vibrations is given in Doebling, et al (1998).…”

“…For this reason, a few frequency ranges are normally chosen, and ideally each frequency range contains 20 to 30 peaks. (Sun, et al 1995) Because of the relatively high frequencies involved, impedance methods are generally more sensitive to local changes in a structure, and traditional vibrations techniques are generally more sensitive to global changes in the structure. With impedance measurements, "a frequency range higher than 200-kHz is found to be favorable in localizing the sensing, while a frequency range lower than 70-khz covers a larger sensing area."…”

“…Perhaps the first successful attempt to implement impedance methods with a SHM system was performed by Sun, et al (1995) In this research, impedance methods were used to monitor damage in a simple truss structure. A damage metric based upon the root-mean-square deviation was used to assess the structural integrity of the truss system.…”

“…Research performed by Chaudhry et al (1995) demonstrated the localized sensitivity of impedance measurements. In this work, impedance measurements were taken near the tail section of an airplane.…”