Degree Type

Dissertation

Date of Award

1982

Degree Name

Doctor of Philosophy

Department

Engineering Science and Mechanics

Abstract

The finite element method has been found to be useful for problems in acoustics. The method as presently applied is not efficient for several common acoustic geometries. This dissertation investigates problems associated with applying the finite element method to acoustic geometries with repeated or standard features and to geometries involving open boundary segments;Substructuring methods are modified and applied to problems involving internal acoustic propagation. It is found that substructuring can be usefully applied for transient response analysis, for frequency response analysis, for repeated geometries, and for parametric studies. Sub-structuring techniques are shown to be an inefficient substitute for higher order elements;Present techniques of modeling open boundary segments are reviewed. A new element shape function which includes both radiant and polynomial terms is developed. The element, termed the radiation element, is shown to be superior to other methods for modeling open boundary segments. The element is also shown to be superior to quadratic elements for modeling axisymmetric internal geometries. The FORTRAN code of a finite element computer program for acoustic applications is included in the Appendix. The program is capable of two-dimensional and axisymmetric superelement generation, potential flow analysis, eigenvalue analysis, and frequency response analysis.

DOI

https://doi.org/10.31274/rtd-180813-5491

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Robert James Bernhard

Language

en

Proquest ID

AAI8221174

File Format

application/pdf

File Size

231 pages

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