Patent ID: 7325456

Claim:
A device for monitoring structural health conditions of an object, comprising: a piezoelectric device including: a bottom cover plate; a plurality of piezoelectric rings concentrically disposed with respect to an axis and positioned on said bottom cover plate; a plurality of concentric filler rings made from an electrically insulating material, each of said piezoelectric rings being interposed between two adjacent ones of said filler rings; electrical connection means for communicating electrical signals to said piezoelectric rings; and a top cover plate positioned over said piezoelectric rings and filler rings, said bottom and top cover plates being adapted to hold said piezoelectric rings and filler rings in place, wherein said electrical connection means are operative to transmit electrical signals that cause one or more of said piezoelectric rings to generate waves or transmit electrical signals developed by one or more of said piezoelectric rings in response to the waves, wherein each of said piezoelectric rings has flat top and bottom surfaces that are perpendicular to said axis and covered with conductive flakes; and wherein each of said top and bottom cover plates includes a plurality of conductive rings concentrically disposed with respect to said axis, each said conductive ring being in contact with one of said conductive flakes and being electrically insulated from the other conductive rings.