Elastic waves that propagate through a waveguide are called
guided waves. A waveguide is a structure with boundaries that
help elastic waves to propagate from one point to another [17].
Waves are reflected by stress-free boundaries. Typical waveguides
are plates, pipes, cylindrical rods and bars. The Lamb Wave is the
guided wave that propagates in a solid plate. The Lamb wave is dispersive
in nature, which means the speed of propagation of the
Lamb wave is dependent on the frequency of the wave. At a single
frequency different modes of Lamb wave propagate with different
speeds