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Elastic wave velocity and attenuation as used to define phases of loading and failure in coal.

Authors
Shea-Albin-VR; Hanson-DR; Gerlick-RE
Source
Denver, CO: U.S. Department of the Interior, Bureau of Mines, RI 9355, 1991 Jan; :1-43
Link
NIOSHTIC No.
10009151
Abstract
This U.S. Bureau of Mines report discusses elastic wave velocity and attenuation behavior as an indicator for changes in load and structural integrity of coal samples. Measuring changes in compressional (p)-wave and shear (s)-wave attenuation and velocity under uniaxial and triaxial compression tests revealed their effectiveness for distinguishing changes in applied load and structural failure of samples. The velocity and attenuation values were used in further calculations such as ratios of p-wave to s-wave values, dynamic elastic constants, normalized velocities, and attenuation coefficients to reveal trends for loading and failure. The behavior of both p-wave and s-wave attenuation and velocity together defines distinct and consistent phases of load change and failure for uniaxial and triaxial tests. The s-wave velocity and attenuation illustrate changing axial load and initial development of microfractures within the sample preceding structural failure more clearly than those of the p-wave. The attenuation and velocity ratios and dynamic elastic constants (except the bulk modulus) respond to closure of small preexisting fractures within the coal sample with initial loading to failure of coal samples. The attenuation coefficients and normalized velocities reveal trends similar to those shown by velocity and attenuation.
Keywords
Wave-propagation; Test-facilities; Mechanical-properties; Velocity; Fractures-materials; Fracture-properties; Failure; Coal-deposits; Loads-forces; Elastic-waves; Attenuation; Nondestructive-tests
Publication Date
19910101
Document Type
IH; Report of Investigations
Fiscal Year
1991
NTIS Accession No.
PB91-230318
NTIS Price
A03
Identifying No.
RI-9355
NIOSH Division
DRC
Source Name
Denver, CO: U.S. Department of the Interior, Bureau of Mines, RI 9355
State
CO
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