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THE EFFECT OF THE ASPECT RATIO ON CRACK‐INDUCED ANISOTROPY 1
Author(s) -
DOUMA J.
Publication year - 1988
Publication title -
geophysical prospecting
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.735
H-Index - 79
eISSN - 1365-2478
pISSN - 0016-8025
DOI - 10.1111/j.1365-2478.1988.tb02183.x
Subject(s) - aspect ratio (aeronautics) , anisotropy , dimensionless quantity , spheres , materials science , range (aeronautics) , condensed matter physics , optics , geometry , mechanics , composite material , physics , mathematics , astronomy
Media containing aligned cracks show anisotropy with respect to elastic wave propagation. There are several models describing the wave propagation in cracked media, most of them only valid for cracks with small aspect ratios. One of these models (Crampin's model) is compared with a model valid for all aspect ratios (Nishizawa's model). The elastic constants and the group velocities are compared for both dry and liquid‐filled inclusions with aspect ratios ranging from 0.0001 (flat cracks) up to 1 (spheres). The difference between both models is small for small aspect ratios but becomes larger for increasing aspect ratios. At a crack density of 0.05 both models give‐within an error of 5%–the same results for aspect ratios up to 0.3. Therefore Crampin's model can be applied to a large range of cracked media even if the aspect ratio of the inclusions is not small. The variation of the anisotropy as a function of the aspect ratio can be studied using Thomsen's dimensionless parameters δ, E and y. They show how inclusions with large aspect ratios result in elliptical anisotropy.