Bifurcation of Nonlinear Normal Modes by Means of Synge’s Stability

2011 ◽  
Author(s):  
Young S. Lee ◽  
Heng Chen
Keyword(s):  
Harmonic Balance ◽  
Coupled Oscillators ◽  
Normal Modes ◽  
Harmonic Balance Method ◽  
Orbital Stability ◽  
Nonlinear Normal Modes ◽  
Energy Transfers ◽  
Wide Range ◽  
Energy Domain ◽  
Nonlinear Normal

We study bifurcation of fundamental nonlinear normal modes (FNNMs) in 2-degree-of-freedom coupled oscillators by utilizing geometric mechanics approach based on Synges concept, which dictates orbital stability rather than Lyapunovs classical asymptotic stability. Use of harmonic balance method provides reasonably accurate approximation for NNMs over wide range of energy; and Floquet theory incorporated into Synges stability analysis predicts the respective bifurcation points as well as their types. Constructing NNMs in the frequency-energy domain, we seek applications to study of efficient targeted energy transfers.

scholarly journals On the Use of the Proper Generalised Decomposition for Solving Nonlinear Vibration Problems

2012 ◽  
Author(s):  
Aurelien Grolet ◽  
Fabrice Thouverez
Keyword(s):  
Nonlinear Vibration ◽  
Harmonic Balance ◽  
A Priori ◽  
Geometrical Nonlinearity ◽  
Normal Modes ◽  
Harmonic Balance Method ◽  
Nonlinear Normal Modes ◽  
Vibration Problems ◽  
Nonlinear Normal ◽  
Proper Orthogonal

This paper presents the use of the so called Proper Generalized Decomposition method (PGD) for solving nonlinear vibration problems. PGD is often presented as an a priori reduction technique meaning that the reduction basis for expressing the solution is computed during the computation of the solution itself. In this paper, the PGD is applied in addition with the Harmonic Balance Method (HBM) in order to find periodic solutions of nonlinear dynamic systems. Several algorithms are presented in order to compute nonlinear normal modes and forced solutions. Application is carried out on systems containing geometrical nonlinearity and/or friction damping. We show that the PGD is able to compute a good approximation of the solutions event with a projection basis of small size. Results are compared with a Proper Orthogonal Decomposition (POD) method showing that the PGD can sometimes provide an optimal reduction basis relative to the number of basis components.

scholarly journals Isolated Response Curves in a Base-Excited, Two-Degree-of-Freedom, Nonlinear System

2015 ◽  
Author(s):  
J. P. Noël ◽  
T. Detroux ◽  
L. Masset ◽  
G. Kerschen ◽  
L. N. Virgin
Keyword(s):  
Nonlinear System ◽  
Harmonic Balance ◽  
Global Analysis ◽  
Normal Modes ◽  
Nonlinear Normal Modes ◽  
Basins Of Attraction ◽  
Response Curves ◽  
Restoring Force ◽  
Nonlinear Normal ◽  
Two Degree Of Freedom

In the present paper, isolated response curves in a nonlinear system consisting of two masses sliding on a horizontal guide are examined. Transverse springs are attached to one mass to provide the nonlinear restoring force, and a harmonic motion of the complete system is imposed by prescribing the displacement of their supports. Numerical simulations are carried out to study the conditions of existence of isolated solutions, their bifurcations, their merging with the main response branch and their basins of attraction. This is achieved using tools including nonlinear normal modes, energy balance, harmonic balance-based continuation and bifurcation tracking, and global analysis.

Forced Response Analysis of Pipes Conveying Fluid by Nonlinear Normal Modes Method and Iterative Approach

2017 ◽  
Vol 13 (1) ◽  
Author(s):  
Feng Liang ◽  
Xiao-Dong Yang ◽  
Ying-Jing Qian ◽  
Wei Zhang
Keyword(s):  
Normal Modes ◽  
Harmonic Balance Method ◽  
Nonlinear Normal Modes ◽  
Forced Response ◽  
Dynamic Responses ◽  
Response Analysis ◽  
Iterative Approach ◽  
Pipes Conveying Fluid ◽  
Nonlinear Normal ◽  
Conveying Fluid

The forced vibration of gyroscopic continua is investigated by taking the pipes conveying fluid as an example. The nonlinear normal modes and a numerical iterative approach are used to perform numerical response analysis. The nonlinear nonautonomous governing equations are transformed into a set of pseudo-autonomous ones by using the harmonic balance method. Based on the pseudo-autonomous system, the nonlinear normal modes are constructed by the invariant manifold method on the state space and substituted back into the original discrete equations. By repeating the above mentioned steps, the dynamic responses can be numerically obtained asymptotically using such iterative approach. Quadrature phase difference between the general coordinates is verified for the gyroscopic system and traveling waves instead of standing waves are found in the time-domain complex modal analysis.

DEGENERATE BIFURCATION SCENARIOS IN THE DYNAMICS OF COUPLED OSCILLATORS WITH SYMMETRIC NONLINEARITIES

2006 ◽  
Vol 16 (01) ◽  
pp. 169-178 ◽  
Author(s):  
O. V. GENDELMAN
Keyword(s):  
Coupled Oscillators ◽  
Coupling Parameter ◽  
Normal Modes ◽  
Nonlinear Normal Modes ◽  
Saddle Node Bifurcation ◽  
High Energies ◽  
Saddle Node ◽  
Weakly Coupled ◽  
Nonlinear Normal ◽  
Infinite Energy

We study the degenerate bifurcations of nonlinear normal modes (NNMs) of an unforced system consisting of a linear oscillator weakly coupled to an essentially nonlinear one. The potentials of both the oscillator and the coupling spring are adopted to be even-power polynomials with non-negative coefficients. Coupling parameter ε is defined and the bifurcations of the nonlinear normal modes structure with change of this coupling parameter are revealed. The degeneracy in the dynamics is manifested by a "bifurcation from infinity" where a saddle-node bifurcation point is generated at high energies, as perturbation of a state of infinite energy. Other (nondegenerate) saddle-node bifurcation points (at least one point) are generated in the vicinity of the point of exact 1 : 1 internal resonance between the linear and nonlinear oscillators. The above bifurcations form multiple-branch structure with few stable and unstable branches. This structure may disappear (for certain choices of the oscillator and coupling potentials) by the mechanism of successive cusp catastrophes with the growth of coupling parameter ε. The above analytical findings are verified by means of direct numerical simulation (conservative Poincaré sections). In the particular case of pure cubic nonlinearity of the oscillator and the coupling spring, an agreement between quantitative analytical predictions and numerical results is observed.

Construction and Use of the Frequency-Energy Plot for a System With Two Essential Nonlinearities

2011 ◽  
Author(s):  
Sean A. Hubbard ◽  
Alexander F. Vakakis ◽  
Lawrence A. Bergman ◽  
D. Michael McFarland
Keyword(s):  
Degrees Of Freedom ◽  
Normal Modes ◽  
Nonlinear Normal Modes ◽  
Present System ◽  
Combined System ◽  
Strongly Nonlinear ◽  
Energy Transfers ◽  
Strongly Nonlinear System ◽  
Nonlinear Normal ◽  
Energy Plane

We consider the problem of depicting possible periodic motions of a strongly nonlinear system in the frequency-energy plane. The particular case of a 2-degree-of-freedom, linear primary structure coupled to a 2-DOF, nonlinear attachment is examined in detail. While there exist numerical tools for the semiautomatic computation of such frequency-energy plots (FEPs), the presence of multiple essential (nonlinearizable) nonlinearities in the present system introduces new challenges in their application. Furthermore, the multiple degrees of freedom of the nonlinear subsystem allow the existence of complex nonlinear normal modes localized there but exhibiting more complicated resonances than those previously observed in the study of a single-DOF nonlinear attachment. The FEP generated for a laboratory-scale mechanical system is interpreted to explain the transitions and energy transfers that occur in the simulated transient response of the combined system following broadband shock excitation.

An Application of the Poincare´ Map to the Stability of Nonlinear Normal Modes

1980 ◽  
Vol 47 (3) ◽  
pp. 645-651 ◽  
Author(s):  
L. A. Month ◽  
R. H. Rand
Keyword(s):  
Floquet Theory ◽  
Poincaré Map ◽  
Normal Modes ◽  
Nonlinear Normal Modes ◽  
Theory Approach ◽  
Poincare Map ◽  
Linearized Stability ◽  
Nonlinear Normal ◽  
The Stability ◽  
Two Degree Of Freedom

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.

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