Parametric Instability of a Moving Particle on a Periodically Supported Infinitely Long String

2008 ◽  
Vol 75 (1) ◽  
Author(s):  
A. V. Metrikine
Keyword(s):  
Parametric Analysis ◽  
Dynamic Instability ◽  
Parametric Instability ◽  
Simplified Model ◽  
Infinite Matrix ◽  
Analytical Validation ◽  
System Parameters ◽  
Stability And Instability ◽  
Moving Particle ◽  
Elastically Supported

A new method is proposed of theoretical analysis of the dynamic instability of a moving object on a periodically supported, infinitely long elastic structure. To demonstrate this method, a simple example is considered of a moving particle on an elastically supported string. The equations are obtained that govern the system parameters that correspond to the boundaries separating stability and instability in the parameter space. These equations are in the form of the determinant of an infinite matrix and are analogous to Hill’s infinite determinant. A parametric analysis of the instability zones is carried out in the plane of the normalized particle mass and particle velocity. The focus is placed on the effect of elasticity and viscosity of the supports. An analytical validation is presented of the numerically obtained instability zones. This is done using a simplified model of the string on the corresponding continuous foundation.

Instability of an Elastically Supported Beam under a Travelling Inertia Load

1970 ◽  
Vol 12 (5) ◽  
pp. 373-376 ◽  
Author(s):  
D. E. Newland
Keyword(s):  
Dynamic Instability ◽  
Buckling Load ◽  
Railway Track ◽  
Axial Buckling ◽  
Elastically Supported ◽  
Bending Wave

It is shown that an unstable bending wave may be excited in an elastically supported beam by a travelling inertia load. Since the occurrence of this dynamic instability reduces the axial buckling load of the beam, the result is relevant to present studies of the temperature buckling of continuous welded railway track.

Dynamic Instability in Quartering Seas—Part III: Nonlinear Effects on Periodic Motions

1997 ◽  
Vol 41 (03) ◽  
pp. 210-223 ◽  
Author(s):  
K. J. Spyrou
Keyword(s):  
Periodic Motion ◽  
Horizontal Plane ◽  
Dynamic Instability ◽  
Parametric Instability ◽  
Nonlinear Effects ◽  
Ship Motions ◽  
Nonlinear Phenomena ◽  
Specific Sequence ◽  
The Stability ◽  
Two Stages

The loss of stability of the horizontal-plane periodic motion of a steered ship in waves is investigated. In earlier reports we referred to the possibility of a broaching mechanism that will be intrinsic to the periodic mode, whereby there will exist no need for the ship to go through the surf-riding stage. However, about this point the discussion was essentially conjectural. In order to provide substance we present here a theoretical approach that is organized in two stages: Initially, we demonstrate the existence of a mechanism of parametric instability of yaw on the basis of a rudimentary, single-degree model of maneuvering motion in waves. Then, with a more elaborate model, we identify the underlying nonlinear phenomena that govern the large-amplitude horizontal ship motions, considering the ship as a multi-degree, nonlinear oscillator. Our analysis brings to light a very specific sequence of phenomena leading to cumulative broaching that involves a change in the stability of the ordinary periodic motion on the horizontal plane, a transition towards subharmonic response and, ultimately, a sudden jump to resonance. Possible means for controlling the onset of such undesirable behavior are also investigated.

scholarly journals Hopf bifurcation for an SIR model with age structure

2021 ◽  
Author(s):  
HUI CAO ◽  
Dongxue Yan ◽  
Xiaxia Xu
Keyword(s):  
Cauchy Problem ◽  
Hopf Bifurcation ◽  
Bifurcation Analysis ◽  
Age Structure ◽  
Equilibrium Points ◽  
Sir Model ◽  
Numerical Examples ◽  
System Parameters ◽  
Stability And Instability ◽  
Densely Defined

This paper deals with an SIR model with age structure of infected individuals. We formulate the model as an abstract non-densely defined Cauchy problem and derive the conditions for the existence of all the feasible equilibrium points of the system. The criteria for both stability and instability involving system parameters are obtained. Bifurcation analysis indicates that the system with age structure exhibits Hopf bifurcation which is the main result of this paper. Finally, some numerical examples are provided to illustrate our obtained results.

The Role of Modal Coupling on the Non-Linear Response of Cylindrical Shells Subjected to Dynamic Axial Loads

2000 ◽  
Author(s):  
Paulo B. Gonçalves ◽  
Zenón J. G. N. Del Prado
Keyword(s):  
Dynamic Instability ◽  
Equations Of Motion ◽  
Cylindrical Shells ◽  
Parametric Instability ◽  
Compressive Load ◽  
Basins Of Attraction ◽  
Dynamic Component ◽  
Linear Ordinary Differential Equations ◽  
Non Linear ◽  
Low Dimensional

Abstract This paper discusses the dynamic instability of circular cylindrical shells subjected to time-dependent axial edge loads of the form P(t) = P0+P1(t), where the dynamic component p1(t) is periodic in time and P0 is a uniform compressive load. In the present paper a low dimensional model, which retains the essential non-linear terms, is used to study the non-linear oscillations and instabilities of the shell. For this, Donnell’s shallow shell equations are used together with the Galerkin method to derive a set of coupled non-linear ordinary differential equations of motion which are, in turn, solved by the Runge-Kutta method. To study the non-linear behavior of the shell, several numerical strategies were used to obtain Poincaré maps, stable and unstable fixed points, bifurcation diagrams and basins of attraction. Particular attention is paid to two dynamic instability phenomena that may arise under these loading conditions: parametric instability and escape from the pre-buckling potential well. The numerical results obtained from this investigation clarify the conditions, which control whether or not instability may occur. This may help in establishing proper design criteria for these shells under dynamic loads, a topic practically unexplored in literature.

Parametric Resonance Characteristics of Woven Fiber Metal Laminated Plates

2019 ◽  
Vol 11 (04) ◽  
pp. 1950034 ◽  
Author(s):  
Elluri Venkata Prasad ◽  
Shishir Kumar Sahu
Keyword(s):  
Parametric Resonance ◽  
Degrees Of Freedom ◽  
Dynamic Instability ◽  
Parametric Instability ◽  
Laminated Plates ◽  
Load Factor ◽  
Harmonic Loading ◽  
Resonance Behavior ◽  
Fiber Metal ◽  
Ply Orientation

The present investigation deals with the assessment of parametric resonance behavior of new aircraft material, i.e., woven fiber metal laminated (FML) plates subjected to in-plane static and harmonic loading using finite element (FE) technique and Bolotin’s method. In this analysis, a four-node isoparametric element with five degrees of freedom per node is adopted. Based on the first-order Reissner–Mindlin theory, the parametric instability of FML plate subjected to in-plane harmonic loading is examined. A MATLAB code is developed for the parametric study on the dynamic stability of FML plates. The reliability of present formulation is checked by comparing numerical results obtained from present FE analysis with the published researches in the field. The influences of several factors, viz. static load factor, aspect ratio, length-to-thickness ratio, number of layers, ply orientation and boundary conditions on the dynamic instability regions are discussed. Significant variations of these factors on dynamic instability zones of FML plates are observed. The instability zones can be used as guidelines for the prediction of the dynamic behavior of FML plates.

Optimum Design of Elastically Supported Gyroscopes for Ship Stabilization

1984 ◽  
Vol 106 (4) ◽  
pp. 387-392
Author(s):  
K.-N. Lee ◽  
A. Seireg
Keyword(s):  
Optimal Design ◽  
Dynamic Model ◽  
Optimum Design ◽  
Design Procedures ◽  
System Parameters ◽  
Ship Roll ◽  
Elastically Supported ◽  
Elastic Spring

The study reported in this paper deals with the development of a dynamic model for the analysis of elastically supported gyroscopic absorber systems for ship stabilization. The gryoscopes are mounted on elastically supported platforms at the fore and aft ends of the ship to minimize both the roll and pitch movements. Springs and dampers are also utilized between the gyroscope gimbal and the platform. Several design configurations of the absorber are considered. Optimal design procedures are utilized to find the system parameters for best performance in each case. The performance of the resulting optimum absorber shows that introducing the elastic spring and damper between the gimbal and platform has a significant effect on reducing the ship-roll action.

Analysis of Flow Induced Vibration Using the Vorticity Transport Equation

1993 ◽  
Vol 115 (3) ◽  
pp. 485-492 ◽  
Author(s):  
Jure Marn ◽  
Ivan Catton
Keyword(s):  
Parametric Analysis ◽  
Dynamic Instability ◽  
Equations Of Motion ◽  
Fluid Motion ◽  
Governing Equations ◽  
Flow Induced Vibration ◽  
The Subject ◽  
An Array Of Cylinders ◽  
Vorticity Transport ◽  
Square Array

Crossflow induced vibrations are the subject of this work. The analysis is two dimensional. The governing equations for fluid motion are solved using linearized perturbation theory and coupled with the equations of motion for cylinders to yield the threshold of dynamic instability for an array of cylinders. Parametric analysis is performed to determine the lowest instability threshold for a rotated square array and correlations are developed relating the dominant parameters. The results are compared with theoretical and experimental data for similar arrays and the discrepancies are discussed.

On Parametric Analysis of Differential Hysteresis

2003 ◽  
Author(s):  
F. Ma ◽  
C. H. Ng ◽  
H. Zhang ◽  
A. Bockstedte ◽  
G. C. Foliente ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Parametric Analysis ◽  
Relative Sensitivity ◽  
Nonlinear Damping ◽  
Sensitivity Analyses ◽  
Simplified Model ◽  
Hysteretic Model ◽  
Differential Model ◽  
Global Sensitivity

The extended Bouc-Wen differential model is one of the most widely accepted phenomenological models of hysteresis in mechanics. It is routinely used in the characterization of nonlinear damping and in system identification. In this paper, the differential model of hysteresis is carefully re-examined and two significant issues are uncovered. First, it is found that the unspecified parameters of the model are functionally redundant. One of the parameters can be eliminated through suitable transformations in the parameter space. Second, local and global sensitivity analyses are conducted to assess the relative sensitivity of each model parameter. Through extensive Monte Carlo simulations, it is found that some parameters of the hysteretic model are rather insensitive. If the values of these insensitive parameters are fixed, a greatly simplified model is obtained.

Parametric Instability of a Rotating Circular Ring With Moving, Time-Varying Springs

2005 ◽  
Vol 128 (2) ◽  
pp. 231-243 ◽  
Author(s):  
Sripathi Vangipuram Canchi ◽  
Robert G. Parker
Keyword(s):  
Parametric Instability ◽  
Circular Ring ◽  
Time Varying ◽  
Ring Gear ◽  
Geometric Description ◽  
Bending Vibrations ◽  
System Parameters ◽  
Ring Rotation ◽  
Special Cases ◽  
Instability Regions

Parametric instabilities of in-plane bending vibrations of a rotating ring coupled to multiple, discrete, rotating, time-varying stiffness spring-sets of general geometric description are investigated in this work. Instability boundaries are identified analytically using perturbation analysis and given as closed-form expressions in the system parameters. Ring rotation and time-varying stiffness significantly affect instability regions. Different configurations with a rotating and nonrotating ring, and rotating spring-sets are examined. Simple relations governing the occurrence and suppression of instabilities are discussed for special cases with symmetric circumferential spacing of spring-sets. These results are applied to identify possible conditions of ring gear instability in example planetary gears.

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