Scattering of Lattice Waves by Static Strain Fields in Crystals

On the basis of nonlinear elasticity theory, the scattering of lattice waves by a static strain field has been treated with special consideration of the elastic anisotropy of wave-propagating medium. A general form for the wave equation in strained medium was derived, and the scattered waves were determined by means of perturbation method by adopting the Born approximation. The Green's function method was conveniently used to determine the displacement of the scattered waves. The general method was applied to the case of scattering of lattice waves incident normally on a screw dislocation in a cubic crystal. The results of the calculation showed that the scattering was very anisotropic with regard to the incident direction and the scattering angle of the waves. It was found that, contrary to the dominance of purely forward scattering in isotropic medium, obliquely forward scattering occurred intensively in crystals.