Experimental investigation on the interface properties evaluation in piezoelectric layered structures by love waves propagation

Love waves can be found much engineering significance in many signal transmission, signal processing and information storage applications by adopting the piezoelectric layered structures. In piezoelectricity, the interaction between elastic and electrical field in such a wave leads to a number of new effects not observed in non-piezoelectric crystals. Due to the thermal mismatch, intrinsic stress and the brittleness nature of piezoelectric ceramics, there exists unavoidable initial stress in piezoelectric layer/substrate structures and imperfections usually occur between the interfaces of above-mentioned structures. These imperfections may influence the propagation behavior of Love waves. Effects of imperfections on the dispersion relations of Love waves in piezoelectric layered structures are taken into account theoretically and experimentally. A new kind of contact-type line-focused transducer is developed for the Love wave to be excited and detected. Experiments concerning the propagation of Love waves in piezoelectric layered structure are carried out to investigate the imperfect interface properties. Results obtained indicate that imperfect interface properties can be effectively evaluated by Love wave propagation under some certain conditions. Experimental results obtained agree well with the theoretical prediction, which also indicate that our developed novel Love wave transducer is effective.