<title>Automated real-time structure health monitoring via signature pattern recognition</title>

Abstract

Described in this paper are the details of an automated real-time structure health monitoring system. The system is based on structural signature pattern recognition. It uses an array ofpiezoceramic (PZ1) patches bonded to the structure as integrated sensor-actuators, an electric impedance analyzer for structural frequency response function (FRF) acquisition and a PC for control and graphic display. An assembled 3-bay truss structure is employed as a test bed. Two issues, the localization of sensing area and the sensor temperature drift, which are Critical for the sneess of this technique are addressed and a novel approach of providing temperature compensation using probability correlation function is presentecL Due to the negligible weight and size of the solid-state sensor array and its ability to sense incipient-type damage, the system can eventually be implemented on many types of structures such as aircraft, spacecraft, large-span dome roof and steel bridges requiring multilocation and real-time health monitoring

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

“…An important factor is the temperature, whose variation affects PZT patch characteristics like permittivity, piezoelectric charge constant, electromechanical coupling factor, capacitance and resonant frequency of the longitudinal oscillation (Annamdas and Soh 2010). Consequently, the EMI technique is affected by a combination of uniform horizontal and vertical translations in the impedance plots (Sun et al 1995). The disbond of the PZT transducer and temperature effects may cause similar variations in the susceptance signal and therefore the temperature changes have to be monitored and treated in the analysis (Overly et al 2009).…”

“…Since Sun et al (1995), different architectures have been proposed to measure the EMI, attempting to avoid cumbersome and expensive equipment. Some solutions are financially less costly and others focus on fast computational processing time.…”

“…Lower frequency ranges cover a larger sensing area, whereas higher frequency ranges may determine the position of the damage (Sun et al 1995). One of the advantages of the highfrequency response is that, at these frequencies, the wavelength of the signal applied to the structure is short enough to detect even small and incipient cracks, which can potentially grow and cause catastrophic failures in aircraft structures (Park and Inman 2005).…”

“…To reach these requirements, nondestructive evaluation methods (NDE) have been considered as promising tools in SHM systems, according to Sun et al (1995);methods for monitoring systems. It is able to identify structural modifi cations (damage) by measuring the EMI of a PZT (leadzirconate-titanate) transducer, which is bonded to (or embedded into) the monitored structure.…”

Influence of Parameter Variation on Electromechanical Admittance Spectrum of a Multiple Degree of Freedom System

“…The dynamic interaction between the PZT patches and the host mechanical structure will result in a unique electrical admittance spectrum, revealing the physical and mechanical property variation in the host structure. Sun et al [2] introduced this technique into damage detection of civil engineering components such as pipeline system, truss structure and steel bridge sections. Taylor et al [3] monitored fatigue failure of a wind turbine rotor blade under cyclic loads based on EMI technique.…”