Application of Resonant Ultrasound Spectroscopy to Determine the Elastic Properties of Macroscopic Rock Samples

Resonant Ultrasound Spectroscopy (RUS) is a method whereby the elastic tensor of a sample is extracted from measured resonance frequencies. Typically, a rectangular parallelepiped sample is placed between two piezoelectric transducers, a source and a detector. The sample is driven at constant voltag...

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Bibliographic Details
Main Authors: McCall, K R, Ulrich, T J, Johnson, P A, Darling, T W, Migliori, A
Format: Report
Language:English
Subjects:
ACOUSTIC ATTENUATION
Acoustics
ANISOTROPY
BASALT
COMPONENT REPORT
ELASTIC PROPERTIES
Geology, Geochemistry and Mineralogy
Mechanics
RESONANCE
RESONANT FREQUENCY
ROCK
RUS(RESONANT ULTRASOUND SPECTROSCOPY)
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Summary:Resonant Ultrasound Spectroscopy (RUS) is a method whereby the elastic tensor of a sample is extracted from measured resonance frequencies. Typically, a rectangular parallelepiped sample is placed between two piezoelectric transducers, a source and a detector. The sample is driven at constant voltage as the frequency is swept through multiple resonances. The measured resonance frequencies are the input to an iterative inversion algorithm that finds the best match between the data and a set of resonances generated from a model. RUS has been used successfully to determine the elastic properties of single crystals of minerals found in the earth's mantle (e.g., Oda et aL, 1992). We are extending the applicability of RUS to macroscopic samples of rock. Rocks are potentially difficult samples on which to apply RUS, because of their high acoustic attenuation (low Q), inhomogeneity, anisotropy, and the difficulty preparing suitable samples. In preliminary measurements, we have analyzed a variety of rock types to determine optimal sample sizes and aspect ratios, the minimum number of resonances necessary for obtaining an accurate inversion, the sensitivity of RUS to anisotropy in rock samples, and the precision of measurements on samples of varying sizes and aspect ratios. Assuming isotropy, we have found that RUS provides reliable results for relatively high Q materials such as basalt, primarily because a large number of resonance frequencies can be accurately determined. This article is from the Proceedings of the Resonance Meeting, Vol. 1 Transcripts, p.66-76. Presented at the Resonance Meeting, National Center for Physical Acoustics, The University of Mississippi, 30 May-1 Jun 1999. Prepared in collaboration with Los Alamos National Laboratory. This article is from ADA398263 Proceedings of the Resonance Meeting. Volume 1. Transcripts