On Discontinuous Dynamics of a Freight Train Suspension System

2014 ◽  
Vol 24 (12) ◽  
pp. 1450163 ◽  
Author(s):  
Dennis O'Connor ◽  
Albert C. J. Luo
Keyword(s):  
Local Stability ◽  
Wedge Angle ◽  
Field Testing ◽  
Suspension System ◽  
Analytical Prediction ◽  
Periodic Motions ◽  
Freight Train ◽  
Suspension Systems ◽  
Testing Data ◽  
Wedge Effect

In this paper, a freight train suspension system is presented for all possible types of motion. The suspension system experiences impacts and friction between wedges and bolster. The impacts cause the chatter motions between wedges and bolster, and the friction will cause the stick and nonstick motions between wedges and bolster. Due to the wedge effect, the suspension system may become stuck and not move, which can cause the suspension to lose functions. To discuss such phenomena in the freight train suspension systems, the theory of discontinuous dynamical systems is used, and the motion mechanism of impacting chatter with stick and stuck is discussed. The analytical conditions for the onset and vanishing of stick motions between the wedges and bolster are presented, and the condition for maintaining stick motion was achieved as well. The analytical conditions are developed for the onset and vanishing conditions for stuck motion. An analytical prediction of periodic motions relative to impacting chatter with stick and stuck motions in the train suspension is performed through the mapping dynamics. The corresponding analyses of local stability and bifurcation are carried out, and the grazing and stick conditions are used to determine periodic motions. Numerical simulations illustrate periodic motions of stick and stuck motions. Finally, from field testing data, the effects of wedge angle on the motions of the suspension are presented to find a more desirable suspension response for design.

Arbitrary Periodic Motions and Grazing Switching of a Forced Piecewise Linear, Impacting Oscillator

2006 ◽  
Vol 129 (3) ◽  
pp. 276-284 ◽  
Author(s):  
Albert C. J. Luo ◽  
Lidi Chen
Keyword(s):  
Nonlinear Dynamics ◽  
Periodic Motion ◽  
Local Stability ◽  
Piecewise Linear ◽  
Analytical Prediction ◽  
Periodic Motions ◽  
Grazing Bifurcation ◽  
Piecewise Linear System ◽  
Local Stability Analysis ◽  
Mapping Structures

The grazing bifurcation and periodic motion switching of the harmonically forced, piecewise linear system with impacting are investigated. The generic mappings relative to the discontinuous boundaries of this piecewise system are introduced. Based on such mappings, the corresponding grazing conditions are obtained. The mapping structures are developed for the analytical prediction of periodic motions in such a system. The local stability and bifurcation conditions for specified periodic motions are obtained. The regular and grazing, periodic motions are illustrated. The grazing is the origin of the periodic motion switching for this system. Such a grazing bifurcation cannot be estimated through the local stability analysis. This model is applicable to prediction of periodic motions in nonlinear dynamics of gear transmission systems.

Grazing Bifurcation and Periodic Motion Switching in a Piecewise Linear, Impacting Oscillator Under a Periodical Excitation

2005 ◽  
Author(s):  
Albert C. J. Luo ◽  
Lidi Chen
Keyword(s):  
Nonlinear Dynamics ◽  
Periodic Motion ◽  
Local Stability ◽  
Piecewise Linear ◽  
Analytical Prediction ◽  
Periodic Motions ◽  
Grazing Bifurcation ◽  
Piecewise Linear System ◽  
Local Stability Analysis ◽  
Mapping Structures

The grazing bifurcation and periodic motion switching of the harmonically forced, piecewise linear system with impacting are investigated. The generic mappings based on the discontinuous boundaries are introduced. Furthermore, the mapping structures are developed for the analytical prediction of periodic motions in such a system. The local stability and bifurcation conditions for specified periodic motions are obtained. The regular and grazing, periodic motions are illustrated. The grazing is the origin of the periodic motion switching for this system. Such a grazing bifurcation cannot be estimated through the local stability analysis. This model is applicable to prediction of periodic motions in nonlinear dynamics of gear transmission systems.

scholarly journals Motion Switching and Chaos of a Particle in a Generalized Fermi-Acceleration Oscillator

2009 ◽  
Vol 2009 ◽  
pp. 1-40 ◽  
Author(s):  
A. C. J. Luo ◽  
Y. Guo
Keyword(s):  
Local Stability ◽  
Analytical Prediction ◽  
Fermi Acceleration ◽  
Periodic Motions ◽  
Chaotic Motions ◽  
Dynamical Behaviors ◽  
Global View ◽  
Mapping Structures ◽  
Stability And Bifurcations ◽  
First Time

Dynamic behaviors of a particle (or a bouncing ball) in a generalized Fermi-acceleration oscillator are investigated. The motion switching of a particle in the Fermi-oscillator causes the complexity and unpredictability of motion. Thus, the mechanism of motion switching of a particle in such a generalized Fermi-oscillator is studied through the theory of discontinuous dynamical systems, and the corresponding analytical conditions for the motion switching are developed. From solutions of linear systems in subdomains, four generic mappings are introduced, and mapping structures for periodic motions can be constructed. Thus, periodic motions in the Fermi-acceleration oscillator are predicted analytically, and the corresponding local stability and bifurcations are also discussed. From the analytical prediction, parameter maps of periodic and chaotic motions are achieved for a global view of motion behaviors in the Fermi-acceleration oscillator. Numerical simulations are carried out for illustrations of periodic and chaotic motions in such an oscillator. In existing results, motion switching in the Fermi-acceleration oscillator is not considered. The motion switching for many motion states of the Fermi-acceleration oscillator is presented for the first time. This methodology will provide a useful way to determine dynamical behaviors in the Fermi-acceleration oscillator.

DYNAMICS OF A HARMONICALLY EXCITED OSCILLATOR WITH DRY-FRICTION ON A SINUSOIDALLY TIME-VARYING, TRAVELING SURFACE

2006 ◽  
Vol 16 (12) ◽  
pp. 3539-3566 ◽  
Author(s):  
ALBERT C. J. LUO ◽  
BRANDON C. GEGG
Keyword(s):  
Relative Motion ◽  
Efficient Method ◽  
Periodic Motion ◽  
Dry Friction ◽  
Local Stability ◽  
Analytical Prediction ◽  
Time Varying ◽  
Periodic Motions ◽  
Mapping Structures ◽  
Excited Oscillator

In this paper, periodic motion in an oscillator moving on the periodically traveling belts with dry friction is investigated. The conditions of stick and nonstick motions for such an oscillator are obtained in the relative motion frame, and the grazing and stick (or sliding) bifurcations are presented as well. The periodic motions of such an oscillator are predicted analytically and numerically, and the analytical prediction is based on the appropriate mapping structures. The local stability and bifurcation for such periodic motions are obtained. The periodic motions are illustrated through the displacement, velocity and force responses in absolute and relative frames. This investigation provides an efficient method to predict periodic motions of such an oscillator involving dry-friction. The significance of this investigation lies in controlling motion of such friction-induced oscillator in industry.

The Challenges of Wide Ranging Viscosity Fluids on Liquid Ultrasonic Flowmeters

2006 ◽  
Author(s):  
Jeffrey L. Walters
Keyword(s):  
Elevated Temperature ◽  
Temperature Effects ◽  
Flow Measurement ◽  
Field Testing ◽  
Signal Propagation ◽  
Oil Fields ◽  
Flow Profile ◽  
Fluid Temperature ◽  
Testing Data ◽  
Novel Approaches

Wide ranging viscosities in ultrasonic flow measurement for liquids is a common pipeline scenario. With ever maturing oil fields and the growth in oilsands production, the trend appears to be towards the higher end viscosities and/or novel approaches towards reducing the viscosities for transportation such as heating. The variable viscosities of the fluids provide some unique challenges to ultrasonic flowmeters not only in terms of flow profile modeling, but also in acoustic signal propagation and application to elevated temperature fluids which likewise affect the accuracy or performance of the measurement. The flow profile interrogation techniques will be discussed with an emphasis on a distributed chord model together with the use of a waveguide technology that minimizes acoustic and fluid temperature effects. A combination of R&D, calibration and field testing data will both demonstrate these challenges as well as show the increased performance that results from the application of these approaches.

scholarly journals Online Adaptive Optimal Control of Vehicle Active Suspension Systems Using Single-Network Approximate Dynamic Programming

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Zhi-Jun Fu ◽  
Bin Li ◽  
Xiao-Bin Ning ◽  
Wei-Dong Xie
Keyword(s):  
Optimal Control ◽  
Dynamic Programming ◽  
Approximate Dynamic Programming ◽  
Control Method ◽  
Active Suspension ◽  
Suspension System ◽  
Lyapunov Theory ◽  
Adaptive Optimal Control ◽  
Suspension Systems ◽  
Optimal Control Method

In view of the performance requirements (e.g., ride comfort, road holding, and suspension space limitation) for vehicle suspension systems, this paper proposes an adaptive optimal control method for quarter-car active suspension system by using the approximate dynamic programming approach (ADP). Online optimal control law is obtained by using a single adaptive critic NN to approximate the solution of the Hamilton-Jacobi-Bellman (HJB) equation. Stability of the closed-loop system is proved by Lyapunov theory. Compared with the classic linear quadratic regulator (LQR) approach, the proposed ADP-based adaptive optimal control method demonstrates improved performance in the presence of parametric uncertainties (e.g., sprung mass) and unknown road displacement. Numerical simulation results of a sedan suspension system are presented to verify the effectiveness of the proposed control strategy.

Estimating concrete strength using field testing data

2014 ◽  
pp. 524-529
Author(s):  
A Colombo ◽  
L Meneghetti ◽  
R Teixeira ◽  
T Bittencourt
Keyword(s):  
Concrete Strength ◽  
Field Testing ◽  
Testing Data

Bifurcation Tree of Period-1 Motion to Chaos in a Pendulum With Periodic Excitation

2016 ◽  
Author(s):  
Yu Guo ◽  
Albert C. J. Luo
Keyword(s):  
Harmonic Amplitude ◽  
Analytical Prediction ◽  
Algebraic Equations ◽  
Periodic Motions ◽  
Bifurcation Tree ◽  
Discrete Maps ◽  
Periodically Driven ◽  
Mapping Structures ◽  
Nonlinear Algebraic Equations ◽  
Analytical Bifurcation Trees

In this paper, the bifurcation trees of period-1 motions to chaos are presented in a periodically driven pendulum. Discrete implicit maps are obtained through a mid-time scheme. Using these discrete maps, mapping structures are developed to describe different types of motions. Analytical bifurcation trees of periodic motions to chaos are obtained through the nonlinear algebraic equations of such implicit maps. Eigenvalue analysis is carried out for stability and bifurcation analysis of the periodic motions. Finally, numerical simulation results of various periodic motions are illustrated in verification to the analytical prediction. Harmonic amplitude characteristics are also be presented.

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