A Novel Material Modulus Function for Modeling Viscoelastic Materials

Accurately modeling damping in engineering structures has plagued scientist and engineers for decades. The integration of viscoelastic materials into engineering structures can reduce undesired vibrations and serve as an effective passive control mechanism. Various techniques have been developed to...

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Bibliographic Details
Main Author: Martin, Luke Andrew
Other Authors: Mechanical Engineering
Format: Others
Published: Virginia Tech 2014
Subjects:
GHM
Online Access:http://hdl.handle.net/10919/26891
http://scholar.lib.vt.edu/theses/available/etd-04152011-140601/
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spelling ndltd-VTETD-oai-vtechworks.lib.vt.edu-10919-268912020-09-26T05:31:32Z A Novel Material Modulus Function for Modeling Viscoelastic Materials Martin, Luke Andrew Mechanical Engineering Inman, Daniel J. Ahmadian, Mehdi Wicks, Alfred L. Kasarda, Mary E. F. Yagla, Jon J. Sorbothane sandwich beam modal viscoelastic complex modulus material modulus function damping GHM MGHM Accurately modeling damping in engineering structures has plagued scientist and engineers for decades. The integration of viscoelastic materials into engineering structures can reduce undesired vibrations and serve as an effective passive control mechanism. Various techniques have been developed to model viscoelastic materials. The growing popularity of finite element analysis in the 1980s and 1990s spawned new techniques for modeling damping in complex structures. The technique defined in this dissertation can be incorporated into finite element models. In metals, the modulus of elasticity can be modeled as a constant. That is, the modulus of elasticity is not treated as a function of frequency in dynamic models. For viscoelastic materials, the modulus of elasticity can be assumed to be constant for static forces and sinusoidal forcing functions. However, when viscoelastic materials undergo excitations from a random or transient forcing function the constant modulus of elasticity assumption may not be valid. This is because the second order equation of motion has non-constant coefficients or coefficients that vary as a function of frequency. The Golla-Hughes-McTavish (GHM) method is a technique used to incorporate the frequency dependency of viscoelastic materials into finite element models. The GHM method is used as a way to alleviate working with second order differential equations with non-constant coefficients. This dissertation presents the theory for a new material modulus function suitable for application within the framework of the GHM method. However, the new material modulus function uses different assumptions and is referred to as the Modified GHM method or MGHM method. The MGHM method is shown to improve the curve fit and damping characteristics of the GHM method. Additionally, the MGHM method is shown to reduce to the GHM method when the original GHM assumptions are imposed. Ph. D. 2014-03-14T20:09:43Z 2014-03-14T20:09:43Z 2011-04-01 2011-04-15 2011-05-06 2011-05-06 Dissertation etd-04152011-140601 http://hdl.handle.net/10919/26891 http://scholar.lib.vt.edu/theses/available/etd-04152011-140601/ LukeAMartin_Dissertation20110506.pdf In Copyright http://rightsstatements.org/vocab/InC/1.0/ application/pdf Virginia Tech
collection NDLTD
format Others
sources NDLTD
topic Sorbothane
sandwich beam
modal
viscoelastic
complex modulus
material modulus function
damping
GHM
MGHM
spellingShingle Sorbothane
sandwich beam
modal
viscoelastic
complex modulus
material modulus function
damping
GHM
MGHM
Martin, Luke Andrew
A Novel Material Modulus Function for Modeling Viscoelastic Materials
description Accurately modeling damping in engineering structures has plagued scientist and engineers for decades. The integration of viscoelastic materials into engineering structures can reduce undesired vibrations and serve as an effective passive control mechanism. Various techniques have been developed to model viscoelastic materials. The growing popularity of finite element analysis in the 1980s and 1990s spawned new techniques for modeling damping in complex structures. The technique defined in this dissertation can be incorporated into finite element models. In metals, the modulus of elasticity can be modeled as a constant. That is, the modulus of elasticity is not treated as a function of frequency in dynamic models. For viscoelastic materials, the modulus of elasticity can be assumed to be constant for static forces and sinusoidal forcing functions. However, when viscoelastic materials undergo excitations from a random or transient forcing function the constant modulus of elasticity assumption may not be valid. This is because the second order equation of motion has non-constant coefficients or coefficients that vary as a function of frequency. The Golla-Hughes-McTavish (GHM) method is a technique used to incorporate the frequency dependency of viscoelastic materials into finite element models. The GHM method is used as a way to alleviate working with second order differential equations with non-constant coefficients. This dissertation presents the theory for a new material modulus function suitable for application within the framework of the GHM method. However, the new material modulus function uses different assumptions and is referred to as the Modified GHM method or MGHM method. The MGHM method is shown to improve the curve fit and damping characteristics of the GHM method. Additionally, the MGHM method is shown to reduce to the GHM method when the original GHM assumptions are imposed. === Ph. D.
author2 Mechanical Engineering
author_facet Mechanical Engineering
Martin, Luke Andrew
author Martin, Luke Andrew
author_sort Martin, Luke Andrew
title A Novel Material Modulus Function for Modeling Viscoelastic Materials
title_short A Novel Material Modulus Function for Modeling Viscoelastic Materials
title_full A Novel Material Modulus Function for Modeling Viscoelastic Materials
title_fullStr A Novel Material Modulus Function for Modeling Viscoelastic Materials
title_full_unstemmed A Novel Material Modulus Function for Modeling Viscoelastic Materials
title_sort novel material modulus function for modeling viscoelastic materials
publisher Virginia Tech
publishDate 2014
url http://hdl.handle.net/10919/26891
http://scholar.lib.vt.edu/theses/available/etd-04152011-140601/
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