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Vibration suppression through stiffness variation and modal disparity.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Vibration suppression through stiffness variation and modal disparity./
Author:	Issa, Jimmy.
Description:	1 online resource (117 pages)
Notes:	Source: Dissertation Abstracts International, Volume: 69-09, Section: B, page: 5727.
Contained By:	Dissertation Abstracts International69-09B.
Subject:	Mechanical engineering. -
Online resource:	click for full text (PQDT)
ISBN:	9780549837176

Vibration suppression through stiffness variation and modal disparity.
Issa, Jimmy.

Vibration suppression through stiffness variation and modal disparity. - 1 online resource (117 pages)

Source: Dissertation Abstracts International, Volume: 69-09, Section: B, page: 5727.

Thesis (Ph.D.)--Michigan State University, 2008.

Includes bibliographical references

Vibration suppression is the main objective of this study. A semi-active and an active vibration control strategy based on stiffness variation are proposed for removing energy from vibrating structures. For the semi-active vibration control strategy, the notion of modal disparity is introduced and exploited as a new method of vibration suppression. For a given structure, modal disparity is a measure of the difference in the mode shapes of the structure in two stiffness states. Modal disparity is validated experimentally in a beam where stiffness variation is induced by application and removal of constraints. In dynamical systems modeled with finite degrees-of-freedom, the application of constraints transfers energy to the unmodeled high-frequency modes, where it is dissipated naturally and quickly. The removal of constraints does not dissipate energy but resets the system for the constraints to be applied again for further reduction of energy. Thus sequential application and removal of constraints eventually dissipates the energy of the system completely. It is shown that energy removal is always possible, even with a random switching schedule, except in one case where the energy is trapped in modes that span invariant subspaces with certain orthogonality properties. The optimal locations and timing of constraint application is investigated with the goal of maximizing energy dissipation through maximal energy transfer to the unmodeled high-frequency modes. For the active control strategy, cable actuators are proposed for removing energy from three-dimensional framed structures. The tension in the cables has two effects on the structure; it increases the stiffness of the structure and applies an external load on the structure. Both effects are used in the design of the active control strategy in which the cable tension is essentially switched between different levels to do negative work. Experimental results are presented to validate the efficacy of the control strategy.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2018

Mode of access: World Wide Web

ISBN: 9780549837176Subjects--Topical Terms:

557493
Mechanical engineering.
Index Terms--Genre/Form:

554714
Electronic books.

Vibration suppression through stiffness variation and modal disparity.
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100 1 $a Issa, Jimmy. $3 1189535
245 1 0 $a Vibration suppression through stiffness variation and modal disparity.
264 0 $c 2008
300 $a 1 online resource (117 pages)
336 $a text $b txt $2 rdacontent
337 $a computer $b c $2 rdamedia
338 $a online resource $b cr $2 rdacarrier
500 $a Source: Dissertation Abstracts International, Volume: 69-09, Section: B, page: 5727.
500 $a Adviser: Ranjan Mukherjee.
502 $a Thesis (Ph.D.)--Michigan State University, 2008.
504 $a Includes bibliographical references
520 $a Vibration suppression is the main objective of this study. A semi-active and an active vibration control strategy based on stiffness variation are proposed for removing energy from vibrating structures. For the semi-active vibration control strategy, the notion of modal disparity is introduced and exploited as a new method of vibration suppression. For a given structure, modal disparity is a measure of the difference in the mode shapes of the structure in two stiffness states. Modal disparity is validated experimentally in a beam where stiffness variation is induced by application and removal of constraints. In dynamical systems modeled with finite degrees-of-freedom, the application of constraints transfers energy to the unmodeled high-frequency modes, where it is dissipated naturally and quickly. The removal of constraints does not dissipate energy but resets the system for the constraints to be applied again for further reduction of energy. Thus sequential application and removal of constraints eventually dissipates the energy of the system completely. It is shown that energy removal is always possible, even with a random switching schedule, except in one case where the energy is trapped in modes that span invariant subspaces with certain orthogonality properties. The optimal locations and timing of constraint application is investigated with the goal of maximizing energy dissipation through maximal energy transfer to the unmodeled high-frequency modes. For the active control strategy, cable actuators are proposed for removing energy from three-dimensional framed structures. The tension in the cables has two effects on the structure; it increases the stiffness of the structure and applies an external load on the structure. Both effects are used in the design of the active control strategy in which the cable tension is essentially switched between different levels to do negative work. Experimental results are presented to validate the efficacy of the control strategy.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2018
538 $a Mode of access: World Wide Web
650 4 $a Mechanical engineering. $3 557493
655 7 $a Electronic books. $2 local $3 554714
690 $a 0548
710 2 $a ProQuest Information and Learning Co. $3 1178819
710 2 $a Michigan State University. $3 810490
773 0 $t Dissertation Abstracts International $g 69-09B.
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3331931 $z click for full text (PQDT)