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THEORY OF ACOUSTOPLASTICITY AND ULTR...

WU, TSUNG-TSONG.

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THEORY OF ACOUSTOPLASTICITY AND ULTRASONIC MEASUREMENTS OF RESIDUAL STRESSES.

Record Type:	Electronic resources : Monograph/item
Title/Author:	THEORY OF ACOUSTOPLASTICITY AND ULTRASONIC MEASUREMENTS OF RESIDUAL STRESSES./
Author:	WU, TSUNG-TSONG.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 1987,
Description:	125 p.
Notes:	Source: Dissertations Abstracts International, Volume: 48-07, Section: B.
Contained By:	Dissertations Abstracts International48-07B.
Subject:	Mechanics. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=8725782

THEORY OF ACOUSTOPLASTICITY AND ULTRASONIC MEASUREMENTS OF RESIDUAL STRESSES.
WU, TSUNG-TSONG.

THEORY OF ACOUSTOPLASTICITY AND ULTRASONIC MEASUREMENTS OF RESIDUAL STRESSES. - Ann Arbor : ProQuest Dissertations & Theses, 1987 - 125 p.

Source: Dissertations Abstracts International, Volume: 48-07, Section: B.

Thesis (Ph.D.)--Cornell University, 1987.

This item must not be sold to any third party vendors.

Acoustoplasticity is the phenomenon that acoustic wave speeds are changed by the stresses and plastic strains in an elastoplastically deformed solid. Although the existing theory of acoustoelasticity can be applied successfully to measure the applied stresses in a body, it was found inadequate for measuring residual stresses and failed to explain the change of acousto-birefringences by homogeneous plastic strains. This thesis is purported to investigate the effect of plastic deformation on acousto-birefringence (the difference of two shear wave speeds polarized at two perpendicular directions) and to develop a theory applicable for measuring residual stresses and textures caused by the change of ultrasonic wave speeds. The continuum theory of small motions superposed on a finitely deformed body is reorganized to form a basis for the theory of acoustoplasticity. From a variety of definitions for incremental stresses and strains, the incremental second Piola-Kirchhoff stress and the incremental Lagrangian strain are chosen to form a new constitutive equation for a plastically deformed body. In the relaxed state the material is characterized by a new set of material moduli, different from those in the natural state. Based on the proposed theory of acoustoplasticity, birefringent formulae for both normal and oblique incident shear waves are derived. From the birefringence measurements at two or more incident angles, the residual stresses and residual strains of a body can be found simultaneously. Experimental results of uniaxial tests on carbon steel (C:0.18%) show that for small plastic strains, the change of acousto-birefringence is linearly proportional to the plastic strain. To verify further the plastic deformation effect in a body with inhomogeneous plastic deformations, four-point bending tests were conducted. The results confirm those found in the uniaxial experiments with homogeneous deformation. The theory of acoustoelasticity recently proposed by Man and Lu (1986) for measuring residual stresses in a body is also discussed in the thesis. The incremental elasticity tensor defined by Man and Lu is shown to be equivalent to the incremental elastic coefficient, providing not only a basis for measuring residual stresses, but a new approach to determine the plastic strains in a body under elastoplastic deformation. (Abstract shortened with permission of author.).Subjects--Topical Terms:

525881
Mechanics.

THEORY OF ACOUSTOPLASTICITY AND ULTRASONIC MEASUREMENTS OF RESIDUAL STRESSES.
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100 1 $a WU, TSUNG-TSONG. $3 3434410
245 1 0 $a THEORY OF ACOUSTOPLASTICITY AND ULTRASONIC MEASUREMENTS OF RESIDUAL STRESSES.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 1987
300 $a 125 p.
500 $a Source: Dissertations Abstracts International, Volume: 48-07, Section: B.
500 $a Publisher info.: Dissertation/Thesis.
502 $a Thesis (Ph.D.)--Cornell University, 1987.
506 $a This item must not be sold to any third party vendors.
506 $a This item must not be added to any third party search indexes.
520 $a Acoustoplasticity is the phenomenon that acoustic wave speeds are changed by the stresses and plastic strains in an elastoplastically deformed solid. Although the existing theory of acoustoelasticity can be applied successfully to measure the applied stresses in a body, it was found inadequate for measuring residual stresses and failed to explain the change of acousto-birefringences by homogeneous plastic strains. This thesis is purported to investigate the effect of plastic deformation on acousto-birefringence (the difference of two shear wave speeds polarized at two perpendicular directions) and to develop a theory applicable for measuring residual stresses and textures caused by the change of ultrasonic wave speeds. The continuum theory of small motions superposed on a finitely deformed body is reorganized to form a basis for the theory of acoustoplasticity. From a variety of definitions for incremental stresses and strains, the incremental second Piola-Kirchhoff stress and the incremental Lagrangian strain are chosen to form a new constitutive equation for a plastically deformed body. In the relaxed state the material is characterized by a new set of material moduli, different from those in the natural state. Based on the proposed theory of acoustoplasticity, birefringent formulae for both normal and oblique incident shear waves are derived. From the birefringence measurements at two or more incident angles, the residual stresses and residual strains of a body can be found simultaneously. Experimental results of uniaxial tests on carbon steel (C:0.18%) show that for small plastic strains, the change of acousto-birefringence is linearly proportional to the plastic strain. To verify further the plastic deformation effect in a body with inhomogeneous plastic deformations, four-point bending tests were conducted. The results confirm those found in the uniaxial experiments with homogeneous deformation. The theory of acoustoelasticity recently proposed by Man and Lu (1986) for measuring residual stresses in a body is also discussed in the thesis. The incremental elasticity tensor defined by Man and Lu is shown to be equivalent to the incremental elastic coefficient, providing not only a basis for measuring residual stresses, but a new approach to determine the plastic strains in a body under elastoplastic deformation. (Abstract shortened with permission of author.).
590 $a School code: 0058.
650 4 $a Mechanics. $3 525881
690 $a 0346
710 2 $a Cornell University. $3 530586
773 0 $t Dissertations Abstracts International $g 48-07B.
790 $a 0058
791 $a Ph.D.
792 $a 1987
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=8725782