A new design and manufacturing process for embedded Lamb waves interdigital transducers based on piezopolymer film

In this work a new technology for designing and manufacturing ultrasonic interdigitat transducers (IDT) is presented. The piezoelectric material used is a metallised piezopolymer film made of polyvinylidene fluoride (PVDF) with electrode pattern obtained with a laser ablation process. Piezopolymer transducer prototypes are designed with wavelength of 8 mm to operate with Lamb waves (symmetrical S-0 mode). An experimental validation of the piezopolymer IDT design is demonstrated with a transmitter-receiver IDT pair embedded in a 3 mm thick carbon fiber reinforced plastic (CFRP) composite laminate. Acoustical response and the electrical impedance have been calculated. These transducers are proposed for monitoring structural integrity of structures/components made of carbon epoxy composite laminates commonly used in spacecrafts, satellite and airplanes. (C) 2005 Elsevier B.V. All rights reserved.