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Scattering of elastic waves in stati...

Yang, Liyong.

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Scattering of elastic waves in statistically anisotropic media.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Scattering of elastic waves in statistically anisotropic media./
Author:	Yang, Liyong.
Description:	184 p.
Notes:	Source: Dissertation Abstracts International, Volume: 64-12, Section: B, page: 6302.
Contained By:	Dissertation Abstracts International64-12B.
Subject:	Engineering, Mechanical. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3116616

Scattering of elastic waves in statistically anisotropic media.
Yang, Liyong.

Scattering of elastic waves in statistically anisotropic media. - 184 p.

Source: Dissertation Abstracts International, Volume: 64-12, Section: B, page: 6302.

Thesis (Ph.D.)--The University of Nebraska - Lincoln, 2003.

The investigation of wave propagation and scattering of ultrasonic waves in heterogeneous, anisotropic media is of substantial interest to quantitative nondestructive evaluation and materials characterization, particularly for ultrasonic techniques. In this dissertation, models for wave propagation and scattering in statistically anisotropic media, such as cracked media and textured media are developed. These models provide insightful information about the wave propagation parameters and can also be used to guide experimental design for determining the microstructure properties for nondestructive evaluation techniques. Compact expressions are derived for attenuations and wave velocities of the quasilongitudinal and two quasishear waves using stochastic wave theory in a generalized dyadic approach. Those derivations are based upon the diagrammatic approach, in which the mean response is governed by the Dyson equation. The Dyson equation is then solved in the Fourier transform domain within the limits of the first-order smoothing approximation (FOSA).Subjects--Topical Terms:

783786
Engineering, Mechanical.

Scattering of elastic waves in statistically anisotropic media.
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035 $a (UnM)AAI3116616
035 $a AAI3116616
040 $a UnM $c UnM
100 1 $a Yang, Liyong. $3 1948677
245 1 0 $a Scattering of elastic waves in statistically anisotropic media.
300 $a 184 p.
500 $a Source: Dissertation Abstracts International, Volume: 64-12, Section: B, page: 6302.
500 $a Adviser: Joseph A. Turner.
502 $a Thesis (Ph.D.)--The University of Nebraska - Lincoln, 2003.
520 $a The investigation of wave propagation and scattering of ultrasonic waves in heterogeneous, anisotropic media is of substantial interest to quantitative nondestructive evaluation and materials characterization, particularly for ultrasonic techniques. In this dissertation, models for wave propagation and scattering in statistically anisotropic media, such as cracked media and textured media are developed. These models provide insightful information about the wave propagation parameters and can also be used to guide experimental design for determining the microstructure properties for nondestructive evaluation techniques. Compact expressions are derived for attenuations and wave velocities of the quasilongitudinal and two quasishear waves using stochastic wave theory in a generalized dyadic approach. Those derivations are based upon the diagrammatic approach, in which the mean response is governed by the Dyson equation. The Dyson equation is then solved in the Fourier transform domain within the limits of the first-order smoothing approximation (FOSA).
520 $a In cracked media, the derivation of explicit expressions of wave attenuations and velocities in a medium with damage from randomly distributed penny-shaped microcracks is first discussed. Under the same framework, wave propagation and scattering in a solid medium permeated by uniaxially aligned and perfectly aligned penny-shaped cracks are then studied, respectively. The resulting attenuations are investigated in terms of the directional, frequency, and damage dependence.
520 $a In the case of polycrystalline media with texture, attenuations and wave velocities are developed in a general orthorhombic material made up of cubic crystallites. The attenuations of each wave type are calculated numerically as a function of dimensionless frequency and wave propagation direction, respectively, for given orientation distribution coefficients (ODCs). The ODCs are, in essence, the coefficients of an expansion of crystallite of orientation distribution function (ODF) in terms of a series of generalized spherical harmonics. The relationship between the phase velocity and recrystallization variables, such as annealing time, is also investigated for specific examples. Finally, numerical results are presented and discussed in terms of the relevant dependent parameters. It is anticipated that these models will improve the understanding of the microstructure characterization for both cracked and textured media. Moreover, the present formulation allows the study of backscattering problems to be examined in a straightforward manner.
590 $a School code: 0138.
650 4 $a Engineering, Mechanical. $3 783786
650 4 $a Applied Mechanics. $3 1018410
650 4 $a Engineering, Materials Science. $3 1017759
690 $a 0548
690 $a 0346
690 $a 0794
710 2 0 $a The University of Nebraska - Lincoln. $3 1024939
773 0 $t Dissertation Abstracts International $g 64-12B.
790 1 0 $a Turner, Joseph A., $e advisor
790 $a 0138
791 $a Ph.D.
792 $a 2003
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3116616