The propagation of antisymmetric Lamb wave in the hollow cylinder

Abstract

The article presents research on the propagation of an antisymmetric Lamb wave mode in a hollow steel cylinder with an outer diameter of 1020 mm and a wall thickness of 16 mm at frequencies of 50 and 120 kHz. Dispersion curves for a pipe and a plate are given, examples of which show their similarity in the frequency range from 5 kHz and the presence of higher-order modes. Experimental studies were carried out using piezoelectric transducers with dry point contact on a spiral welded pipe. The research results showed the combined effect of the geometric anisotropy and anisotropy of the pipe material properties on the propagation velocity of the antisymmetric Lamb wave mode. The maximum difference in velocity depending on the angle of deviation of the wave propagation trajectory (deviation angle) was 35 and 55 m/s at a frequency of 50 and 120 kHz, respectively. The effect of the pipe wall thickness on the character of the dependence of the velocity on the deviation angle in the presence of dispersion was established, which amounted to 20 m/s per 1 mm of wall thickness for a given pipe geometry. A qualitative description of the formation of the shape of the dependence of the wave velocity on the deviation angle, which has a minimum at 30 degrees and a maximum at 90 degrees, is presented.