The modeling of viscoelastic circular plates for use as waveguide absorbers.
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Authors
Hettema, Charles Dean.
Subjects
waveguide absorber
viscoelastic
plate
Mindlin thin plate theory
viscoelastic
plate
Mindlin thin plate theory
Advisors
Shin, Young S.
Date of Issue
1988-09
Date
September 1988
Publisher
Language
en_US
Abstract
A long standing concern of the Navy has been the need to reduce
structural vibrations in plates, such as ship's hulls. Recently, it was
proposed to use waveguide absorbers as a means to reduce structural
vibrations. A waveguide absorber is a device which is made from damping
material but mounted to the structure at a point rather than the full
surface. A waveguide absorber removes and then dissipates vibrational
energy from the structure through traveling waves. The performance of a
waveguide absorber is determined from the driving point impedance, the
ratio of force to velocity at the attachment point. This study has determined
the theoretical driving point impedance for viscoelastic circular plates.
The constitutive relations for viscoelastic material were evaluated
and it was proven that a complex Young's modulus and shear modulus
can be used to represent the viscoelastic material. Mindlin's theory for
elastic isotropic plates, with complex moduli, was used to solve for the
driving point impedance. The solutions are in terms of Bessel functions.
Poisson's boundary conditions were used at the free edge of the circular
plate, and clamped boundary conditions were used at the attachment point,
which is at the center of the plate. A non-numeric language, REDUCE,
was used to solve for the driving point impedance given the appropriate
equations of motion and boundary conditions. The complex Bessel
functions, needed for the results of the REDUCE program, were generated
by a FORTRAN program. To validate the results of this study, elastic and
viscoelastic plates were tested to determine their driving point impedance.
A comparison of the theoretical results and the experimental results shows
that there is agreement for all cases studied.
Type
Thesis
Description
Series/Report No
Department
Mechanical Engineering
Organization
Naval Postgraduate School (U.S.)
Identifiers
NPS Report Number
Sponsors
Funder
Format
184 p.
Citation
Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.