Longitudinal Ultrasonic Wave Propagation Research Articles

Internal friction in A15 and C15 superconductors in the temperature range 4-150K

Measurements of the internal friction for the propagation of longitudinal ultrasonic waves in the kHz range have been made for samples of Nb3Sn, V 25.25 at.% Si, HfV2 and ZrV2 all of which undergo lattice transformations above their superconducting transition temperatures. Large peaks in the internal friction are observed just below the lattice transformation temperatures of HfV2 and ZrV2, but not for Nb3Sn and V 27.25 at.% Si, though the latter does exhibit a much smaller peak at a temperature above the transformation.

Effects of Magnetic Field on Attenuation of Ultrasonic Waves in a Nematic Liquid Crystal

The effects of the magnitude and direction of a steady magnetic field on the propagation of longitudinal ultrasonic waves in N-(p-methoxybenzylidene)—p-butylaniline have been investigated as a function of frequency and path length. The anisotropy of the measured ultrasonic attenuation is in good agreement with a theory of ultrasonic-wave propagation in nematic liquid crystals based on micropolar continuum mechanics. The variation of the attenuation with frequency from 5–85 MHz is, however, inconsistent with present theories. Measurements of velocity and dispersion are also reported.

Non-Destructive Evaluation of Green Ceramic Body Density by Ultrasonic Technique

Laboratory measurements of spatial density distribution in green ceramic tiles were implemented using ultrasonic contact coupling measurement method. The main objective of these measurements is to measure spatial density distribution in pressed green ceramic tiles. Measurements of longitudinal ultrasonic wave propagation velocity were carried out using pulse and correlation methods and the tile density values were calculated. Evaluation of the measurement method, estimation of uncertainty of measurements and analysis of further improvements purposed to adapt it for on-line measurements in a production process were carried out. Ill. 7, bibl. 16, tabl. 1 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.111.5.360

Sound propagation in the polar phase of KH2 PO4

Abstract The propagation of longitudinal ultrasonic waves along the ferroelectric c axis has been investigated in the close vicinity of the transition temperature of KH 2 PO 4 . Data on the elastic anomaly and the polarization relaxation time are obtained and analyzed.