Geometric anisotropy of velocity of horizontally polarized shear wave in pipe

Abstract

A finite element model has been developed to study the propagation velocity of a horizontally polarized shear waves (SH-waves) in pipes of different diameters depending on geometrical parameters, excitation parameters, physical and elastic properties of the pipe material. The results of studies of the geometric anisotropy of the group and phase velocities of the SH-wave for a pipe with a diameter of 1020 mm with a wall thickness of 16 mm are presented. It has been established that in the case of isotropic properties of the pipe material, the velocity on the outer cylindrical surface in the direction of the envelope is 50 m/s more than on the generatrix. The radiation patterns of the SH-wave are given for the studied pipe size with radiation along the generatrix and envelope of the pipe. The results of experimental studies are in satisfactory agreement with the results of modeling.

The propagation of antisymmetric Lamb wave in the hollow cylinder

“…These extrema are explained by the simultaneous influence of the anisotropy of the pipe material properties and the geometric anisotropy (figure 6). The appearance of the maximum (figure 6b) is primarily explained by the presence of geometric anisotropy, as described in [49,51], and its displacement relative to the pipe envelope (90 degrees) is associated with the anisotropy of the material properties (figure 6c). This shift will be the greater, the greater the anisotropy of the material properties ( figure 6a).…”

“…Since geometric anisotropy has the same effect on the wave velocity at any frequency [50,51], changes in the velocity range are associated with the anisotropy of the material properties and, to the greatest extent, with the velocity dispersion, caused by the influence of the pipe geometry. In this case, the more pronounced the velocity dispersion, the greater the influence on the change in the wave velocity is exerted by the pipe geometry.…”

“…When testing pipe wall thickness using an antisymmetric Lamb wave mode, the analysis of the results becomes more difficult, since all guided wave types are influenced by both the anisotropy of the pipe material properties and the geometric anisotropy. Studies on the influence of geometric anisotropy on the propagation velocity of the symmetric Lamb wave mode and the horizontally polarized shear wave are presented in [49][50][51]. Geometric anisotropy can change the wave velocity depending on the pipe geometry within the range up to 300 m/s from the calculated theoretical value.…”