Investigations of Ultrasonic Wave Interactions at Boundaries Separating Anisotropic Materials. Progress Report

摘要

The studies of the interaction of waves with interfaces between generally anisotropic media were supported experimentally. Two boundary condition on the interface were considered: rigid, and slip. The latter boundary condition describes dislocation boundaries and slip on grain boundaries. It was shown that reflection from such an interface is much stronger than from a rigid bond. A device was designed based on the diffraction of waves on periodic gratings. An anomalous phenomenon was found in the reflection of elastic waves from an interface between anisotropic crystals. It was found that the domain of permissible incident angles splits into disjoint pieces for certain crystal cuts. In this way, a new branch for the reflection coefficient was found. A sample from a Ni crystal was prepared. Another experiment was carried out on critical angles in backscattering. The general computer programs are being adapted to interactive algorithms for the PDP-11 with real time plotting of results on graphic displays. The Schlieren Visualization System was improved by adding capabilities for visualization of impulse ultrasonic signals. (ERA citation 11:011768)