Scattering of Surface Acoustic Waves at the Boundaries of Wedge-like Regions

Abstract

One of the widespread defects typical for a real surface, is its sharp break. The breaks of different types are commonly encountered on the Earth’s surface, namely, the precipices and deep, wide spreading cracks. They occur inevitably in any technical construction. The simplest theoretical model of an arbitrary break is an elastic wedge with angle θ at the vertex. Therefore, the problem of interaction of surface acoustic waves, especially of Rayleigh waves, with the edge of an elastic wedge has already been investigated for more than 20 years in such fields of science and technology as seismology, ultrasonic surface testing, and failure mechanics [12.1-9]. Recently, this problem has aroused considerable interest among the specialists in acoustoelectronics who intend to use wedges as effective frequency independent reflectors of surface waves [12.10], in devices employing the mutual transformation of surface and bulk waves [12.11, 12], as well as for suppression of false signals in delay lines and surface acoustic wave filters [12.13]. The main practical problems in acoustoelectronics are to determine the wedge opening angles for which the reflection of waves incident at given angles is maximal. Sometimes other problems can be stated: to find the wedge angle corresponding to the minimal reflection or maximal radiation of bulk waves, for example, when cyclic delay lines are designed or false signals are being defeated.