Modified lead titanate/polymer 1-3 composite transducers for structural health monitoring

Lamb wave techniques provide an effective means for inspecting large areas of thin structures. Defects arising from corrosion, cracking, adhesive debonding etc. can be monitored continuously by permanently embedding sensors on the structure. However, with the permanently embedded sensors, multiple wave modes are normally generated making the received signals complex to analyze. Interdigital transducers (IDT's) can be used to achieve mode control, giving the capability to excite individual modes. This significantly enhances the ability to extract meaningful information from the received signals. PVDF is commonly used with appropriate electrodes to excite the desired wave mode in the structure. However, due to its low electromechanical coupling coefficient, performance on structures like multi-layered plates and carbon fiber composites is very poor. 1-3 piezocomposites with high electromechanical coupling and bandwidth are designed to overcome the limitations of PVDF. Transducers designed with modified lead titanate are tested on a multi-layered structure to detect delamination at the metal-epoxy interface.