Peculiarities of quasi-longitudinal elastic wave propagation through the interface between isotropic and anisotropic media: Theoretical and experimental study

Abstract

The peculiarities of elastic wave propagation in a bilayer medium are studied theoretically and experimentally. One (isotropic) layer was an acrylic glass plate, and the other (anisotropic) was a quartz sin gle crystal. In experiments, the elastic waves were generated by a piezoelectric transmitter and received by a piezoelectric transducer contacting the surface of the model medium. The propagation time of a quasi lon gitudinal wave was determined using high order statistics. In the general case, the incident elastic waves are split at the interface between the layers: beams undergo double reflection and triple refraction. The measured dependences of the propagation times of quasi longitudinal split waves on the angles of refraction are in sat isfactory agreement with the calculated ones. The calculation was performed by solving the Christoffel equa tion with allowance for the boundary conditions.

Investigation into the seismoacoustic properties of specific polycrystalline materials used in nuclear reactors

“…Our study, as well as the results of [10], showed that the predicted effect of multiple splitting of quasi longi tudinal and quasi transverse elastic waves at an interface between different media could not be experimentally observed for a number of technical reasons. We believe their analysis will make it possible to formulate the nec essary requirements for the most appropriate materials and improve the experimental technique.…”

“…Acrylic glass has a density ρ 1 = 1.19 g/cm 3 and the following Lamé parameters: λ = 4534 ± 136 MPa and μ = 1943 ± 58 MPa [10].…”

“…In this context, an urgent problem is to perform test experiments (based on results obtained by different calculation tech niques) on model samples of materials with well known properties in order to estimate the conditions under which this effect can be detected at elastic wave transmission through an interface between two media. In the first stage, experiments were conducted on sam ples composed of acrylic glass and single crystal quartz [10]. Then this experimental study was contin ued on a model assembly composed of polycrystalline graphite (an anisotropic material) and acrylic glass (isotropic layer).…”

Forced Oscillations in the System of Anisotropic Stripe-half-plane with Hard and Sliding Connection of Media. Comparative Characteristics of Properties of Energy Fields

“…For anisotropic models of semi-infinite substrates the influence of the properties of border discontinuities on the dispersion curves and surface waves was investigated [1], [2]. The authors of [3] and [4] studied the acoustic effects observed in the elastic wave propagation in layered anisotropic media.…”