Piezoelectric transducer embedded in a composite plate: Application to Lamb wave generation

Abstract

The aim of this paper is to show that Lamb waves may be effectively generated using piezoelectric transducers embedded inside a composite plate, for nondestructive evaluation and health monitoring applications. A cylindrical transducer embedded in a composite host plate is considered. The electrical impedance of the transducer alone in vacuum and then of the embedded transducer, which allows the identification of the resonance modes, have been obtained by the finite element method (FEM). Moreover, the displacement fields in the plate, which allow the identification of the types of Lamb waves, have been computed at the resonance frequencies. Comparison between the FEM results and the Lamb wave dispersion curves of the host material are in good agreement. Experimental results (electrical impedance, frequency response, and phase velocities) concerning a composite plate specimen containing the same piezoelectric transducer inside it are shown. A good agreement is generally obtained between numerical and experimental results. In addition, it has been shown that the radial mode of the embedded transducer, which has a high coupling coefficient (around 50%), can be used to generate S0 Lamb waves.

Tuned Lamb Wave Excitation and Detection with Piezoelectric Wafer Active Sensors for Structural Health Monitoring

“…In recent years, several investigators (Chang, 1995(Chang, , 1998Keilers and Chang, 1995;Agrawal, 1996;Moulin et al, 1997;Wang and Chang, 2000;Dupont et al, 2001;Lin and Yuan, 2001a,b;Diamandi et al, 2002;DiazValdes and Soutis, 2002;Ihn and Chang, 2002;Giugiutiu and Zagrai, 2000;Giugiutiu et al, 2002;) have explored the generation and detection of structural waves with piezoelectric wafer active sensors (PWAS). Most of the methods used in conventional NDE, such as pitch-catch, pulse echo, and phased arrays, have also been demonstrated experimentally with PWAS (Giurgiutiu et al, , 2003.…”

Application of the Piezoelectricity in an Active and Passive Health Monitoring System

“…We will see in Section 3.4 that this choice does not affect the results of damage location in passive mode. Moreover, a general rule [15] of ultrasound emission is to excite the emitting element at its natural resonances rather than at any frequency because this method enables a very efficient conversion from electric to mechanic energy. It also means that special care must be taken to choose the thickness, width and length of the piezoelectric elements.…”

“…Figure 3.c shows the real displacement field of the piezoelectric under excitation at 250 kHz frequency, and it allows one to identify it as a transverse mode. The coupling coefficient of this mode could be determined using the following equation [15]:…”

Laser Generated Lamb Waves in Composite Materials Using Embedded Fiber Optic Delivery System

“…In effect, their low Curie point is not compatible with the curing temperature of the composite materials in which one want to embed them. Piezoceramics like PZT are generally used for both surface and embedded acoustic generation and detection [4][5][6], but they suffer from low mechanic properties, fragility, and large size as compared to the ply thickness (125 Jlm for carbon/epoxy composite materials).…”