Wedge elastic waves, with applications to ultrasonic non-destructive testing

Wedge elastic waves are localised vibration modes, both symmetric and anti-symmetric, propagating along tips of elastic wedges. Their existence has been first predicted numerically in 1972 by Lagasse, and then they have been investigated both theoretically and experimentally in a large number of works. The essentially one-dimensional nature of these waves makes them ideally suitable for ultrasonic non-destructive inspection of edges in wedge-like and plate-like structures of different forms and shapes, such as turbine blades, cutting tools, etc. In the present paper, propagation of wedge elastic waves in wedges of different types is discussed, with the emphasis on the theory of antisymmetric mode propagation in slender wedges developed by the present author using the geometrical acoustics approach. This theory is powerful enough to be applicable to wedges of arbitrary shapes, curved wedges and truncated wedges. In all these cases, with the exception of ideal linear elastic wedges, wedge elastic waves are dispersive. Theory of scattering of wedge elastic waves on small defects located on sharp wedge edges is considered as well using perturbation theory approach. Finally, some theoretical and experimental results are discussed regarding different aspects of propagation and scattering of wedge elastic waves relevant to NDT applications