The boundary element method applied to static and dynamic crack problems using hypersingular boundary integral equations

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dc.contributor.advisor Thomas J. Rudolphi
dc.contributor.advisor Frank J. Rizzo
dc.contributor.author Krishnasamy, Gunaseelan
dc.contributor.department Engineering Science and Mechanics
dc.date 2018-08-15T04:27:26.000
dc.date.accessioned 2020-07-02T06:13:33Z
dc.date.available 2020-07-02T06:13:33Z
dc.date.copyright Mon Jan 01 00:00:00 UTC 1990
dc.date.issued 1990
dc.description.abstract <p>The need for hypersingular boundary integral equations in crack problems is motivated through acoustic and elastic wave scattering from a thin screen and crack. By integrating over a small (not necessarily symmetric) neighborhood about the singular point, and the rest of the boundary, and identifying terms from the integrals over the two surfaces which cancel each other, the finite-part of the hypersingular integral is defined for curved surfaces in both two and three dimensions. Stokes' theorem is used to regularize the hypersingular integrals to a form conducive to simple numerical integration techniques. With no prior assumptions on the discretizasion or integration by parts, this method results in integrals which are at most weakly singular. The equivalence of this approach to the finite-part of the hypersingular integral is established;The necessary condition on the density function for the hypersingular integral equation to have meaning and the consequences on the solution of not satisfying the necessary conditions is discussed. This new formulation places restrictions on the choice of shape functions and the possible location of the collocation points within elements due to the smoothness requirement on the density function. Such restrictions for regular boundary integral equations with Cauchy principal value integrals are also discussed. The different kinds of integrals encountered in a hypersingular boundary integral equation such as weakly singular integrals, nearly singular integrals and regular area and line integrals are studied. Discretization considerations for precise and efficient numerical computation of these integrals in the context of the boundary element method is established and the influence of discretization on the solution is highlighted through numerical examples. Examples are chosen from problems of acoustic and elastic wave scattering from thin screens and cracks in three dimensions.</p>
dc.format.mimetype application/pdf
dc.identifier archive/lib.dr.iastate.edu/rtd/9449/
dc.identifier.articleid 10448
dc.identifier.contextkey 6359980
dc.identifier.doi https://doi.org/10.31274/rtd-180813-9175
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath rtd/9449
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/82549
dc.language.iso en
dc.source.bitstream archive/lib.dr.iastate.edu/rtd/9449/r_9101360.pdf|||Sat Jan 15 02:33:12 UTC 2022
dc.subject.disciplines Applied Mechanics
dc.subject.disciplines Mechanical Engineering
dc.subject.keywords Engineering science and mechanics
dc.subject.keywords Engineering mechanics
dc.title The boundary element method applied to static and dynamic crack problems using hypersingular boundary integral equations
dc.type article
dc.type.genre dissertation
dspace.entity.type Publication
thesis.degree.level dissertation
thesis.degree.name Doctor of Philosophy
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