Abstract/Details

Three problems in nonlinear dynamics with 2:1 parametric excitation


2006 2006

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Abstract (summary)

Parametric excitation is epitomized by the Mathieu equation, + (δ + ϵ cos t)x = 0, which involves the characteristic feature of 2:1 resonance. This thesis investigates three generalizations of the Mathieu equation: (1) the effect of combining 2:1 and 1:1 parametric drivers: + (δ + ϵ cos t + ϵ cos ω t)x = 0; (2) the effect of combining parametric excitation near a Hopf bifurcation: + (δ + ϵ cos t)x + ϵAx˙ + ϵ(β1x3 + β 2x2 + β 3xx˙2 + β43) = 0; (3) the effect of combining delay with cubic nonlinearity: + (δ + ϵ cos t)x + ϵγx3 = ϵβx(t - T).

Chapter 3 examines the first of these systems in the neighborhood of 2:1:1 resonance. The method of multiple time scales is used including terms of O2) with three time scales. By comparing our results with those of a previous work on 2:2:1 resonance, we are able to approximate scaling factors which determine the size of the instability regions as we move from one resonance to another in the δ-ω plane.

Chapter 4 treats the second system which involves the parametric excitation of a Hopf bifurcation. The slow flow obtained from a perturbation method is investigated analytically and numerically. A wide variety of bifurcations are observed, including pitchforks, saddle-nodes, Hopfs, limit cycle folds, symmetry-breaking, homoclinic and heteroclinic bifurcations. Approximate analytic expressions for bifurcation curves are obtained using a variety of methods, including normal forms. We show that for large positive damping, the origin is stable, whereas for large negative damping, a quasiperiodic behavior occurs. These two steady states are connected by a complicated series of bifurcations which occur as the damping is varied.

Chapter 5 examines the third system listed. Three different types of phenomenon are combined in this system: 2:1 parametric excitation, cubic nonlinearity, and delay. The method of averaging is used to obtain a slow flow which is analyzed for stability and bifurcations. We show that certain combinations of the delay parameters β and T cause the 2:1 instability region in the δ-ϵ plane to become significantly smaller, and in some cases to disappear. We also show that the delay term behaves like effective damping, adding dissipation to a conservative system.

Indexing (details)


Subject
Mechanical engineering;
Mechanics
Classification
0548: Mechanical engineering
0346: Mechanics
Identifier / keyword
Applied sciences; Delay differential equation; Mathieu equation; Nonlinear dynamics; Parametric excitation
Title
Three problems in nonlinear dynamics with 2:1 parametric excitation
Author
Morrison, Tina Marie
Number of pages
146
Publication year
2006
Degree date
2006
School code
0058
Source
DAI-B 67/07, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
9780542789328
Advisor
Rand, Richard H.
University/institution
Cornell University
University location
United States -- New York
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3227288
ProQuest document ID
305323778
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/305323778/abstract
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