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Interface crack in nonhomogeneous bonded materials of finite thickness.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Interface crack in nonhomogeneous bonded materials of finite thickness./
Author:	Chen, Yaofeng.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 1990,
Description:	224 p.
Notes:	Source: Dissertations Abstracts International, Volume: 52-11, Section: B.
Contained By:	Dissertations Abstracts International52-11B.
Subject:	Mechanics. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9109563
ISBN:	9798207251516

Interface crack in nonhomogeneous bonded materials of finite thickness.
Chen, Yaofeng.

Interface crack in nonhomogeneous bonded materials of finite thickness. - Ann Arbor : ProQuest Dissertations & Theses, 1990 - 224 p.

Source: Dissertations Abstracts International, Volume: 52-11, Section: B.

Thesis (Ph.D.)--Lehigh University, 1990.

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

In a recently developed material forming method called Functional Gradient Materials as well as applications of material deposition processes such as Ion Plating, composite materials are being created where the interface possesses a gradually varying material composition and properties. This study was directed at when there is a crack in such an interface, and sought to find parameters that govern the crack growth such as the crack tip stress intensity factors, strain energy release rate and probable direction of crack extension. The mixed boundary value problem involved two materials of finite thickness with an interface crack to be formulated in plane strain or generalized plane stress. One material is homogeneous and the other nonhomogeneous with an exponential variation in the y-direction. Fourier transforms was applied to Navier's equations to derive a system of singular integral equations with simple Cauchy kernel and Fredholm kernels. The x-derivative of the two crack opening displacements, called density functions, are the unknowns. Extensive asymptotic expansions of the kernels, which were the algebraic sum of rational functions of 7 by 7 and 8 by 8 determinant as the numerator and denominator the elements of which were complex expressions, were obtained. The asymptotic analysis was needed to separate the Cauchy kernel and to facilitate numerical computation. The problem was solved numerically by converting to a system of linear algebraic equations where the integral equations are discretized at collocation points. Stress field near the crack tip have the characteristics of square root singularity and the stress intensity factors together with other related parameters were obtained. Cases for a wide range of degrees of nonhomogeneity and combinations of material thicknesses to crack length ratios were computed with loadings of uniform normal stress and uniform shear. The results of a special case where both materials are of large thicknesses compare very well with documented results of an otherwise the same case of two half planes. The technique developed in this study is useful for fracture mechanics study of composite materials that have a nonhomogeneous interface. The results compiled are especially well suited for thin film cases which is characteristic of the majority of applications intended.

ISBN: 9798207251516Subjects--Topical Terms:

525881
Mechanics.
Subjects--Index Terms:

bonded materials

Interface crack in nonhomogeneous bonded materials of finite thickness.
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100 1 $a Chen, Yaofeng. $3 3689443
245 1 0 $a Interface crack in nonhomogeneous bonded materials of finite thickness.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 1990
300 $a 224 p.
500 $a Source: Dissertations Abstracts International, Volume: 52-11, Section: B.
500 $a Publisher info.: Dissertation/Thesis.
500 $a Advisor: Erdogan, Fazil.
502 $a Thesis (Ph.D.)--Lehigh University, 1990.
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 In a recently developed material forming method called Functional Gradient Materials as well as applications of material deposition processes such as Ion Plating, composite materials are being created where the interface possesses a gradually varying material composition and properties. This study was directed at when there is a crack in such an interface, and sought to find parameters that govern the crack growth such as the crack tip stress intensity factors, strain energy release rate and probable direction of crack extension. The mixed boundary value problem involved two materials of finite thickness with an interface crack to be formulated in plane strain or generalized plane stress. One material is homogeneous and the other nonhomogeneous with an exponential variation in the y-direction. Fourier transforms was applied to Navier's equations to derive a system of singular integral equations with simple Cauchy kernel and Fredholm kernels. The x-derivative of the two crack opening displacements, called density functions, are the unknowns. Extensive asymptotic expansions of the kernels, which were the algebraic sum of rational functions of 7 by 7 and 8 by 8 determinant as the numerator and denominator the elements of which were complex expressions, were obtained. The asymptotic analysis was needed to separate the Cauchy kernel and to facilitate numerical computation. The problem was solved numerically by converting to a system of linear algebraic equations where the integral equations are discretized at collocation points. Stress field near the crack tip have the characteristics of square root singularity and the stress intensity factors together with other related parameters were obtained. Cases for a wide range of degrees of nonhomogeneity and combinations of material thicknesses to crack length ratios were computed with loadings of uniform normal stress and uniform shear. The results of a special case where both materials are of large thicknesses compare very well with documented results of an otherwise the same case of two half planes. The technique developed in this study is useful for fracture mechanics study of composite materials that have a nonhomogeneous interface. The results compiled are especially well suited for thin film cases which is characteristic of the majority of applications intended.
590 $a School code: 0105.
650 4 $a Mechanics. $3 525881
653 $a bonded materials
653 $a crack
653 $a fracture mechanics
690 $a 0346
710 2 $a Lehigh University. $3 515436
773 0 $t Dissertations Abstracts International $g 52-11B.
790 $a 0105
791 $a Ph.D.
792 $a 1990
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9109563