On the Stability of Forced Radial Oscillations of an Experimental Spring Pendulum

Author(s):  
Philip V. Bayly ◽  
Lawrence N. Virgin

Abstract The elastic pendulum is a 2-degree-of-freedom, nonlinear device in which the pendulum bob may slide up and down the pendulum arm subject to the restoring force of a linear spring. In this study, radial motion (motion along the arm) is excited directly. Responses to this excitation include purely radial oscillations as well as swinging motion due to a 2:1 internal resonance. Changes in the behavior of the nonlinear spring pendulum occur when, under the control of a parameter, radial oscillations become unstable and are replaced by radial plus swinging motion. This bifurcation is explored analytically, numerically and experimentally, using the basic ideas of Floquet theory. Poincaré sampling is used to reduce the problem of describing the stability of a limit cycle to the easier task of defining the stability of the fixed point of a Poincaré map.

The elastic pendulum is a two-degree-of-freedom, nonlinear device in which the primary mass slides up and down the pendulum arm subject to the restoring force of a linear spring. In this study, radial motion (motion along the arm) is excited directly. Responses to this excitation include purely radial motion as well as swinging motion due to a 2:1 internal resonance. Changes in the behaviour of the nonlinear spring-pendulum occur when, under the control of a parameter. one response becomes unstable and is replaced by another. These bifurcations are explored analytically, numerically and experimentally, using the basic ideas of Floquet theory. Poincaré sampling is used to reduce the problem of describing the stability of a limit cycle to the easier task of defining the stability of the fixed point of a Poincaré map. Empirical estimates of characteristic multipliers in four-dimensional state space are obtained by examining transient behaviour after perturbations; the Karhunen-Loeve decomposition is used to identify dominant local modes in these transients.


2004 ◽  
Vol 26 (3) ◽  
pp. 157-166
Author(s):  
Nguyen Van Khang ◽  
Thai Manh Cau

In this paper the incremental harmonic balance method is used to calculate periodic vibrations of nonlinear autonomous multip-degree-of-freedom systems. According to Floquet theory, the stability of a periodic solution is checked by evaluating the eigenvalues of the monodromy matrix. Using the programme MAPLE, the authors have studied the periodic vibrations of the system multi-degree van der Pol form.


2017 ◽  
Vol 2017 ◽  
pp. 1-9
Author(s):  
Zijian Yin ◽  
Hongbin Chen

We use the Floquet theory to analyze the stability of periodic solutions of Lienard type equations under the asymptotic linear growth of restoring force in this paper. We find that the existence and the stability of periodic solutions are determined primarily by asymptotic behavior of damping term. For special type of Lienard equation, the uniqueness and stability of periodic solutions are obtained. Furthermore, the sharp rate of exponential decay of the stable periodic solutions is determined under suitable conditions imposed on restoring force.


1967 ◽  
Vol 9 (3) ◽  
pp. 190-197 ◽  
Author(s):  
B. Porter

The method of D-partition is used to analyse the stability of a two-degree-of-freedom system subjected to a delayed restoring force of the kind which causes chatter in certain types of machine tool. The central feature of the analysis is the reduction of a stabliity problem involving a transcendental characteristic equation to a much simpler problem concerning the roots of a related algebraic equation. The results of the exact analysis are compared with approximate results obtained by assuming that the normal modes of the two-degree-of-freedom system can be decoupled.


Filomat ◽  
2017 ◽  
Vol 31 (15) ◽  
pp. 4933-4944
Author(s):  
Dongseung Kang ◽  
Heejeong Koh

We obtain a general solution of the sextic functional equation f (ax+by)+ f (ax-by)+ f (bx+ay)+ f (bx-ay) = (ab)2(a2 + b2)[f(x+y)+f(x-y)] + 2(a2-b2)(a4-b4)[f(x)+f(y)] and investigate the stability of sextic Lie *-derivations associated with the given functional equation via fixed point method. Also, we present a counterexample for a single case.


2012 ◽  
Vol 2012 (1) ◽  
pp. 81 ◽  
Author(s):  
Hassan Kenary ◽  
Hamid Rezaei ◽  
Yousof Gheisari ◽  
Choonkil Park

1980 ◽  
Vol 47 (3) ◽  
pp. 645-651 ◽  
Author(s):  
L. A. Month ◽  
R. H. Rand

The stability of periodic motions (nonlinear normal modes) in a nonlinear two-degree-of-freedom Hamiltonian system is studied by deriving an approximation for the Poincare´ map via the Birkhoff-Gustavson canonical transofrmation. This method is presented as an alternative to the usual linearized stability analysis based on Floquet theory. An example is given for which the Floquet theory approach fails to predict stability but for which the Poincare´ map approach succeeds.


2013 ◽  
Vol 2013 ◽  
pp. 1-18 ◽  
Author(s):  
Bamadev Sahoo ◽  
L. N. Panda ◽  
G. Pohit

The nonlinear vibration of a travelling beam subjected to principal parametric resonance in presence of internal resonance is investigated. The beam velocity is assumed to be comprised of a constant mean value along with a harmonically varying component. The stretching of neutral axis introduces geometric cubic nonlinearity in the equation of motion of the beam. The natural frequency of second mode is approximately three times that of first mode; a three-to-one internal resonance is possible. The method of multiple scales (MMS) is directly applied to the governing nonlinear equations and the associated boundary conditions. The nonlinear steady state response along with the stability and bifurcation of the beam is investigated. The system exhibits pitchfork, Hopf, and saddle node bifurcations under different control parameters. The dynamic solutions in the periodic, quasiperiodic, and chaotic forms are captured with the help of time history, phase portraits, and Poincare maps showing the influence of internal resonance.


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