Deviation of the modal waves excited by an ultrasonic monochromatic beam in an anisotropic layer

Abstract

The aim of the Note is to describe the physical phenomenon of the excitation of modal waves, such as Lamb waves, in anisotropic media by a monochromatic incident beam, and to explain the deviation of the modal wave beam so created. Using a stationary phase approach, the modal wave beam is found to be deviated in the direction normal to the modal slowness curve. Due to the anisotropy, this direction is no longer in the sagittal plane.