Resonance phenomena of Lamb waves scattering by a finite crack in a solid layer

The paper is concerned with diffraction of Lamb waves by a finite crack, parallel to surfaces, in an elastic layer. The solution is constructed by the method of multiple diffractions at the edges of the crack. It is shown that the solution is identical with the solution obtained previously by the generalized Wiener–Hopf method. The resonance phenomena associated with the diffraction of Lamb waves by a finite crack are analyzed. The contribution of the different Lamb waves, generated in the crack zone, to the transmitted and reflected fields, is considered. An approximation of the solution, associated with incorporation of a finite number of Lamb waves, excited in the region of the layer occupied by the crack is discussed. Simple approximate equations are presented for resonance frequencies.