Ultrasonic Field Modeling in Non-Planar and Inhomogeneous Structures Using Distributed Point Source Method

Persistent Link:
http://hdl.handle.net/10150/195602
Title:
Ultrasonic Field Modeling in Non-Planar and Inhomogeneous Structures Using Distributed Point Source Method
Author:
Das, Samik
Issue Date:
2008
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Ultrasonic wave field is modeled inside non-planar and inhomogeneous structures using a newly developed mesh-free semi-analytical technique called Distributed Point Source Method (DPSM). Wave field inside a corrugated plate which is a non-planar structure is modeled using DPSM when the structure is excited by a bounded acoustic beam generated by a finite-size transducer. The ultrasonic field is computed both inside the plate and in the surrounding fluid medium. It is observed that the reflected beam strength is weaker for the corrugated plate in comparison to that of the flat plate, as expected. Whereas the backward scattering is found to be stronger for the corrugated plate. DPSM generated results in the surrounding fluid medium are compared with the experimental results.Ultrasonic wave field is also modeled inside inhomogeneous structures. Two types of inhomogeneity are considered - a circular hole and a damaged layered half-space. Elastic wave scattering inside a half-space containing a circular hole is first modeled using DPSM when the structure is excited with a bounded acoustic beam. Then the ultrasonic wave field is computed in presence and absence of a defect in a layered half-space. For the layered problem geometry it is shown how the layer material influences the amount of energy that propagates through the layer and that penetrates into the solid half-space when the solid structure is struck by a bounded acoustic beam. It is also shown how the presence of a crack and the material properties of the layer material affect the ultrasonic fields inside the solid and fluid media.After solving the above problems in the frequency domain the DPSM technique is extended to produce the time domain results by the Fast Fourier Transform technique. Time histories are obtained for a bounded beam striking an elastic half-space. Numerical results are generated for normal and inclined incidences, for defect-free and cracked half-spaces. A number of useful information that is hidden in the steady state response can be obtained from the transient results.
Type:
text; Electronic Dissertation
Keywords:
DPSM; Inhomogeneous; Non-planar; Transient; Ultrasonic; wave scattering
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Engineering Mechanics; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Kundu, Tribikram
Committee Chair:
Frantziskonis, George; Kemeny, John; Missoum, Samy

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleUltrasonic Field Modeling in Non-Planar and Inhomogeneous Structures Using Distributed Point Source Methoden_US
dc.creatorDas, Samiken_US
dc.contributor.authorDas, Samiken_US
dc.date.issued2008en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractUltrasonic wave field is modeled inside non-planar and inhomogeneous structures using a newly developed mesh-free semi-analytical technique called Distributed Point Source Method (DPSM). Wave field inside a corrugated plate which is a non-planar structure is modeled using DPSM when the structure is excited by a bounded acoustic beam generated by a finite-size transducer. The ultrasonic field is computed both inside the plate and in the surrounding fluid medium. It is observed that the reflected beam strength is weaker for the corrugated plate in comparison to that of the flat plate, as expected. Whereas the backward scattering is found to be stronger for the corrugated plate. DPSM generated results in the surrounding fluid medium are compared with the experimental results.Ultrasonic wave field is also modeled inside inhomogeneous structures. Two types of inhomogeneity are considered - a circular hole and a damaged layered half-space. Elastic wave scattering inside a half-space containing a circular hole is first modeled using DPSM when the structure is excited with a bounded acoustic beam. Then the ultrasonic wave field is computed in presence and absence of a defect in a layered half-space. For the layered problem geometry it is shown how the layer material influences the amount of energy that propagates through the layer and that penetrates into the solid half-space when the solid structure is struck by a bounded acoustic beam. It is also shown how the presence of a crack and the material properties of the layer material affect the ultrasonic fields inside the solid and fluid media.After solving the above problems in the frequency domain the DPSM technique is extended to produce the time domain results by the Fast Fourier Transform technique. Time histories are obtained for a bounded beam striking an elastic half-space. Numerical results are generated for normal and inclined incidences, for defect-free and cracked half-spaces. A number of useful information that is hidden in the steady state response can be obtained from the transient results.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectDPSMen_US
dc.subjectInhomogeneousen_US
dc.subjectNon-planaren_US
dc.subjectTransienten_US
dc.subjectUltrasonicen_US
dc.subjectwave scatteringen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineEngineering Mechanicsen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorKundu, Tribikramen_US
dc.contributor.chairFrantziskonis, Georgeen_US
dc.contributor.chairKemeny, Johnen_US
dc.contributor.chairMissoum, Samyen_US
dc.contributor.committeememberFrantziskonis, Georgeen_US
dc.contributor.committeememberKemeny, Johnen_US
dc.contributor.committeememberMissoum, Samyen_US
dc.identifier.proquest10056en_US
dc.identifier.oclc659750603en_US
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