Propagation of bounded ultrasonic beams in anisotropic media

A method of computing the elastic displacement and stress in an anisotropic elastic medium (crystal) when the medium is excited at its surface by a given displacement or stress is developed. In particular, it is shown how arbitrary boundary conditions generally induce both diagonal and off-diagonal stresses and longitudinal, as well as transverse, displacements. A number of special cases which can be handled analytically are discussed in detail, and a perturbation theory for narrow angle beams is developed. Comparisons are made with previous works which considered propagation of plane waves in nonpure mode directions.