Lamb wave propagation in three-layered composites

The characteristic equation for Lamb waves in three-layered solid composites with arbitrary thickness of each layer are derived in this paper.Two important boundary conditions,i.e.rigid and slip boundary conditions,between neighbored layers are considered and the dispersion curves with different boundaries are demonstrated.Numerical computations of the particle displacement distributions along the thickness direction are made for the lowest normal modes s₀ and a₀