2 dimensional modelling of lateral modes in 1-3 piezocomposites

On account of their periodic structure 1-3 piezocomposites have spurious modes which are due to the acoustic waves undergoing Bragg-scattering in the elastic lattice. In the case of piezocomposite plates, lateral resonances are generated by multiple reflections of Lamb waves between structure discontinuities. However, for 2-2 composites several authors have simplified the theoretical approach by analysing the problem in terms of transverse waves travelling in a 1-D periodic medium of infinite thickness. They have shown that this hypothesis provides theoretical predictions with good accuracy. In this paper, by using the same assumption, a simple model for predicting the first and second lateral behavior in 1-3 piezocomposite is developed. Experimental results of lateral frequencies and displacement field at the composite surface measured with an interferometric laser technique are given and compared to theoretical predictions