A translated rigid ellipsoidal inclusion in an elastic medium

1991 ◽  
Vol 434 (1892) ◽  
pp. 571-585 ◽  
Keyword(s):  
Elastic Medium ◽  
Elastic Field ◽  
Transversely Isotropic ◽  
Ellipsoidal Inclusion ◽  
Arbitrary Orientation ◽  
Isotropic Matrix ◽  
The Matrix ◽  
Ellipsoidal Surface ◽  
Axis Of Symmetry ◽  
Anisotropic Elastic

A rigid ellipsoidal inclusion is embedded at arbitrary orientation in a homogeneous, arbitrarily anisotropic, elastic matrix and is translated infinitesimally by an externally imposed force. We find directly the relation between the force and translation vectors, and the stress, strain and rotation concentrations over the ellipsoidal surface, without having to solve the equations of equilibrium in the matrix, or the fundamental ones of a point force. We refer particularly then to a spheroid aligned along the axis of symmetry of a transversely isotropic matrix, and subsequently to the full elastic field of a general ellipsoid in an isotropic matrix.

A rotated rigid ellipsoidal inclusion in an elastic medium

1991 ◽  
Vol 433 (1887) ◽  
pp. 179-207 ◽  
Keyword(s):  
Elastic Field ◽  
Ellipsoidal Inclusion ◽  
Arbitrary Orientation ◽  
Governing Equations ◽  
Simple Singularity ◽  
The Matrix ◽  
Ellipsoidal Surface ◽  
Rotation Vectors ◽  
Anisotropic Elastic ◽  
Full Solution

A rigid ellipsoidal inclusion is embedded at arbitrary orientation in a homogeneous, arbitrarily anisotropic, elastic matrix and is rotated infinitesimally by means of an imposed couple. Far away the matrix remains either unstrained or at a prescribed uniform strain. A simple ‘singularity’ representation of the elastic field is proposed. It yields directly the relation between the couple and rotation vectors, and the stress, strain and rotation concentrations over the ellipsoidal surface, without having to solve either the governing equations of equilibrium in the matrix, or the fundamental ones of a point force. A full solution is given for an isotropic matrix.

Elastic waves in anisotropic media

1959 ◽  
Vol 253 (1275) ◽  
pp. 563-580 ◽  
Keyword(s):  
Point Source ◽  
Elastic Medium ◽  
Elastic Waves ◽  
Isotropic Medium ◽  
Transversely Isotropic ◽  
Anisotropic Media ◽  
Transversely Isotropic Medium ◽  
Anisotropic Elastic Medium ◽  
Anisotropic Elastic ◽  
Fourier Integrals

The displacements due to a radiating point source in an infinite anisotropic elastic medium are found in terms of Fourier integrals. The integrals are evaluated asymptotically, yielding explicit expressions for displacements at points far from the source. The relative amplitudes of waves from a point source are thus determined, and it is found that although in general the decay of wave amplitudes is proportional to the distance from the source, it is possible that in certain directions the decay is less than this. The method used in this paper is also shown to be an alternative way of deriving known results concerning the geometry of the propagation of disturbances. As an example, the radiation in a transversely isotropic medium from an isolated force varying harmonically with time is discussed.

Moveout approximations for P- and SV-waves in dip-constrained transversely isotropic media

Geophysics ◽  
2013 ◽  
Vol 78 (6) ◽  
pp. C53-C59 ◽  
Author(s):  
Véronique Farra ◽  
Ivan Pšenčík
Keyword(s):  
Transversely Isotropic ◽  
Arbitrary Orientation ◽  
Transversely Isotropic Medium ◽  
Weak Anisotropy ◽  
Transversely Isotropic Media ◽  
Isotropic Media ◽  
Axis Of Symmetry ◽  
Dip Angle ◽  
P And Sv Waves ◽  
Axes Of Symmetry

We generalize the P- and SV-wave moveout formulas obtained for transversely isotropic media with vertical axes of symmetry (VTI), based on the weak-anisotropy approximation. We generalize them for 3D dip-constrained transversely isotropic (DTI) media. A DTI medium is a transversely isotropic medium whose axis of symmetry is perpendicular to a dipping reflector. The formulas are derived in the plane defined by the source-receiver line and the normal to the reflector. In this configuration, they can be easily obtained from the corresponding VTI formulas. It is only necessary to replace the expression for the normalized offset by the expression containing the apparent dip angle. The final results apply to general 3D situations, in which the plane reflector may have arbitrary orientation, and the source and the receiver may be situated arbitrarily in the DTI medium. The accuracy of the proposed formulas is tested on models with varying dip of the reflector, and for several orientations of the horizontal source-receiver line with respect to the dipping reflector.

Matrix laminate composites: Realizable approximations for the effective moduli of piezoelectric dispersions

1999 ◽  
Vol 14 (1) ◽  
pp. 49-63 ◽  
Author(s):  
L. V. Gibiansky ◽  
S. Torquato
Keyword(s):  
Effective Properties ◽  
Matrix Material ◽  
Transversely Isotropic ◽  
Effective Moduli ◽  
Phase Volume ◽  
Laminate Composites ◽  
Effective Coefficients ◽  
The Matrix ◽  
Axis Of Symmetry ◽  
Free Parameters

This paper is concerned with the effective piezoelectric moduli of a special class of dispersions called matrix laminates composites that are known to possess extremal elastic and dielectric moduli. It is assumed that the matrix material is an isotropic dielectric, and the inclusions and composites are transversely isotropic piezoelectrics that share the same axis of symmetry. The exact expressions for the effective coefficients of such structures are obtained. They can be used to approximate the effective properties of any transversely isotropic dispersion. The advantages of our approximations are that they are (i) realizable, i.e., correspond to specific microstructures; (ii) analytical and easy to compute even in nondegenerate cases; (iii) valid for the entire range of phase volume fractions; and (iv) characterized by two free parameters that allow one to “tune” the approximation and describe a variety of microstructures. The new approximations are compared with known ones.

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