Flexible ultrasonic transducers for structural heath monitoring of Graphite/Epoxy composite

Flexible ultrasonic transducers (FUTs) are presented for structural health monitoring (SHM) and non-destructive evaluation (NDE) of graphite/epoxy (Gr/Ep) composites. These FUTs are fabricated using a sol-gel spray technique to coat piezoelectric films onto 75 m thick titatanium (Ti) or 50 m thick polymide (Pl) membranes. The main merit of FUTs is their on-site installation capability because they may be glued or attached to a host Gr/Ep structure with planar or curved surfaces. The flexibility of such FUTs is achieved due to the thin substrates, piezoelectric ceramics and electrodes. Tapered Gr/Ep layers bonded onto each side of an aluminum (Al) plate and on a Gr/Ep composite plate with artificial delaminations were investigated. An induction type non-contact method for the evaluation of Gr/EP composites using FUTs is also demonstrated. Such a non-contact technique may be desired for SHM and NDE of rotating composite components.Peer reviewed: YesNRC publication: Ye