MESH-FREE MODELING OF ULTRASONIC FIELDS GENERATED BY TRANSDUCERS AND ACOUSTIC MICROSCOPES

Persistent Link:
http://hdl.handle.net/10150/195234
Title:
MESH-FREE MODELING OF ULTRASONIC FIELDS GENERATED BY TRANSDUCERS AND ACOUSTIC MICROSCOPES
Author:
Yanagita, Tamaki
Issue Date:
2009
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:
With the gain in momentum of the structural health monitoring field in the last two decades, the popularity of ultrasonic nondestructive testing (NDT) has grown. However, ultrasonic NDT requires an expert to perform the testing and can be time consuming and costly when measured wave patterns in testing become extremely complex. A computer simulation of these tests can be utilized as a guide during actual evaluations or as a tool to train technicians. Presented in this dissertation is the development of models which simulate such acoustic phenomena as may arise in NDT. These models were developed using the distributed point source method (DPSM) for its proven capability to represent ultrasonic fields.Four sets of boundary conditions that arise from different types of commonly used acoustic transducers are modeled, enabling the visualization of the ultrasonic fields produced by the transducers. The transducer models exhibit good agreement with existing analytical solutions.In addition, the effect of a small cavity located at or near the focal point of an acoustic microscope is discussed. For this application the DPSM technique is modified so that inversion of a large global matrix is avoided, significantly improving the computational efficiency. The model shows that, as the pressure goes to zero, the velocity increases at the location of a cavity. Simulations demonstrate that the microscope is able to sense changes in position of the cavity by variations in the measured ratio of reflected to incident acoustic force.The field generated by an interferometric acoustic microscope is also presented. Qualitative agreement between the DPSM model and the experimental results of fields generated in a homogeneous fluid are obtained for a three-element lens. In the presence of a solid interface, the pressure on the edges of a converging beam near the fluid-solid interface is greater for a three-element lens than for single-element lens. A multi-element lens is also shown to exhibit oscillations in the pressure slightly above the interface.
Type:
text; Electronic Dissertation
Keywords:
Acoustic Microscope; Distributed Point Source Method; Transducer; Ultrasonic Field
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Aerospace Engineering; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Kundu, Tribikram
Committee Chair:
Kundu, Tribikram

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleMESH-FREE MODELING OF ULTRASONIC FIELDS GENERATED BY TRANSDUCERS AND ACOUSTIC MICROSCOPESen_US
dc.creatorYanagita, Tamakien_US
dc.contributor.authorYanagita, Tamakien_US
dc.date.issued2009en_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.abstractWith the gain in momentum of the structural health monitoring field in the last two decades, the popularity of ultrasonic nondestructive testing (NDT) has grown. However, ultrasonic NDT requires an expert to perform the testing and can be time consuming and costly when measured wave patterns in testing become extremely complex. A computer simulation of these tests can be utilized as a guide during actual evaluations or as a tool to train technicians. Presented in this dissertation is the development of models which simulate such acoustic phenomena as may arise in NDT. These models were developed using the distributed point source method (DPSM) for its proven capability to represent ultrasonic fields.Four sets of boundary conditions that arise from different types of commonly used acoustic transducers are modeled, enabling the visualization of the ultrasonic fields produced by the transducers. The transducer models exhibit good agreement with existing analytical solutions.In addition, the effect of a small cavity located at or near the focal point of an acoustic microscope is discussed. For this application the DPSM technique is modified so that inversion of a large global matrix is avoided, significantly improving the computational efficiency. The model shows that, as the pressure goes to zero, the velocity increases at the location of a cavity. Simulations demonstrate that the microscope is able to sense changes in position of the cavity by variations in the measured ratio of reflected to incident acoustic force.The field generated by an interferometric acoustic microscope is also presented. Qualitative agreement between the DPSM model and the experimental results of fields generated in a homogeneous fluid are obtained for a three-element lens. In the presence of a solid interface, the pressure on the edges of a converging beam near the fluid-solid interface is greater for a three-element lens than for single-element lens. A multi-element lens is also shown to exhibit oscillations in the pressure slightly above the interface.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectAcoustic Microscopeen_US
dc.subjectDistributed Point Source Methoden_US
dc.subjectTransduceren_US
dc.subjectUltrasonic Fielden_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineAerospace Engineeringen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorKundu, Tribikramen_US
dc.contributor.chairKundu, Tribikramen_US
dc.contributor.committeememberNikravesh, Parvizen_US
dc.contributor.committeememberMissoum, Samyen_US
dc.contributor.committeememberKamel, Husseinen_US
dc.identifier.proquest10752en_US
dc.identifier.oclc659753582en_US
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