Comparison of metrics to monitor and compensate for piezoceramic debonding in structural health monitoring

Abstract

This article investigates metrics to assess and compensate for the degradation of the adhesive layer of surface-bonded piezoceramic transducers for structural health-monitoring applications. Capacitance, resonance frequency, and modal damping parameters are derived from admittance curves using a lumped parameter model to monitor the degradation of the transducer adhesive layer. A pitch-catch configuration is then used to discriminate the effect of bonding degradation on actuation and sensing. It is shown that below the first mechanical resonance frequency of the piezoceramic transducers, the degradation causes a decrease in the amplitude of the transmitted and received signals, while above resonance, in addition to a decrease in the amplitude of the transmitted and received signals, a linear phase shift is observed. A signal-correction factor is proposed to adjust signals based on adhesive degradation evaluated using the measured modal damping. The benefits of the signal-correction factor are demonstrated in the frequency domain for both the A 0 and S 0 modes.

Simultaneous Influence of Static Load and Temperature on the Electromechanical Signature of Piezoelectric Elements Bonded to Composite Aeronautic Structures

“…Common sensor diagnostics procedures using the EM signature are based on the analysis of the susceptance B( f ) [2,11,[29][30][31]. Let B ref ( f ) be the susceptance in the reference healthy case and B unk ( f ) the susceptance in the current unknown state.…”

Investigation of the effects of structure-sensor interaction on piezoceramic transducers for structural health monitoring applications

“…In the case of the work presented by Mulligan et al (2012) the transducers were not degraded, the observed behaviour was attributed to changes occurring to the PZT transducer resonance which moves to lower frequencies as the debonded area increases. The simulation of modal damping shows that it like capacitance decreases gradually with decrease in bonded area, experiment measurements show good correlation with simulation ( (Mulligan et al, 2012), p9).…”

“…The experimental data suggest that there is alternation between bond area degradation (increase in capacitance) and transducer damage (reduction in capacitance ( (Mulligan et al, 2012), p2). In the case of the work presented by Mulligan et al (2012) the transducers were not degraded, the observed behaviour was attributed to changes occurring to the PZT transducer resonance which moves to lower frequencies as the debonded area increases.…”

“…The work of Lanzara et al (2009) shows that the effect on electro-mechanical coupling of transducer debonding is influenced by the shape of the debonded area as well as the size of the disbond, something the work of Mulligan et al (2012) did not investigate. Lanzara et al (2009) demonstrate that as the total size of an asymmetric shaped disbond increased the signal phase delay increased to a maximum of 18% for a 30% disbond area ( (Lanzara et al, 2009), p1704).…”

“…"The measurement of slope is not accurate for intermediate levels of bond area degradation" ( (Mulligan et al, 2012), p2). A comparison of numerical and experimental work by Mulligan et al (2012), (p8) shows that as bond area coverage decreases simulations predict there is a gradual increase in capacitance, experimental work shows that the effect is much more complicated and harder to quantify with intermediate levels of degradation not following the predicted trend.…”