Experimental analysis of plate waves in 1-3 piezoelectric composite materials

Plate waves inside the piezoelectric layer are much involved in the elements cross-coupling in transducer arrays for medical imaging. In this work, such waves are analysed in 1-3 piezocomposite materials on the basis of a conventional guided modes formalism where the piezocomposite is considered as an homogeneous medium. Cross-coupling measurements have been made on two different transducer arrays. It is shown how the analysis in terms of symmetrical Lamb waves gives an interesting qualitative interpretation, explaining most of the cross-coupling amplitude variations with frequency. Results show that the 0^th and 3^rd symmetrical Lamb waves are mainly involved in coupling inside composite plates. The S₀ mode is responsible for the inter-element coupling whereas the S₃ mode enlarges the effective width of the excited element