PIEZOELECTRIC TRANSDUCER EMBEDDED IN A COMPOSITE PLATE - APPLICATION TO LAMB WAVE GENERATION

The aim of this paper is to show that Lamb waves may be effectively ge nerated using piezoelectric transducers embedded inside a composite pl ate, for nondestructive evaluation and health monitoring applications. A cylindrical transducer embedded in a composite host plate is consid ered. The electrical impedance of the transducer alone in vacuum and t hen 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 ide ntification of the types of Lamb waves, have been computed at the reso nance frequencies. Comparison between the FEM results and the Lamb wav e dispersion curves of the host material are in good agreement. Experi mental results (electrical impedance, frequency response, and phase ve locities) concerning a composite plate specimen containing the same pi ezoelectric transducer inside it are shown. A good agreement is genera lly obtained between numerical and experimental results. In addition, it has been shown that the radial mode of the embedded transducer, whi ch has a high coupling coefficient(around 50%), can be used to generat e S-0 Lamb waves. (C) 1997 American Institute of Physics.