Experiments on Quasiperiodic Wheel Shimmy

2009 ◽  
Vol 4 (3) ◽  
Author(s):  
Dénes Takács ◽  
Gábor Stépán
Keyword(s):  
Vehicle Dynamics ◽  
Vibration Frequencies ◽  
Lateral Vibration ◽  
Laboratory Measurements ◽  
Stability Boundaries ◽  
System Parameters ◽  
Quasiperiodic Oscillation ◽  
Delay Effects ◽  
Tire Models ◽  
Wheel Shimmy

The lateral vibration of towed wheels—so-called shimmy—is one of the most exciting phenomena of vehicle dynamics. We give a brief description of a simple rig of elastic tire that was constructed for laboratory measurements. A full report is given on the experimental investigation of this rig from the identification of system parameters to the validation of stability boundaries and vibration frequencies of shimmy motion. The experimental results confirm the validity of those tire models that include delay effects. A peculiar quasiperiodic oscillation detected during the experiments is explained by numerical simulations of the nonlinear time-delayed mathematical model.

Experiments on Quasi-Periodic Wheel Shimmy

2007 ◽  
Author(s):  
De´nes Taka´cs ◽  
Ga´bor Ste´pan
Keyword(s):  
Vehicle Dynamics ◽  
Periodic Oscillation ◽  
Lateral Vibration ◽  
Laboratory Measurements ◽  
Stability Boundaries ◽  
Quasi Periodic Oscillation ◽  
System Parameters ◽  
Low Degree ◽  
Delay Effects ◽  
Wheel Shimmy

The lateral vibration of towed wheels — so-called shimmy — is one of the most exciting phenomena of vehicle dynamics. We give a brief description of a low degree of freedom rig of elastic tyre that was constructed for laboratory measurements. A full report is given on the experimental investigation of this rig from the identification of system parameters to the validation of stability boundaries and vibration frequencies of shimmy motion. The experimental results confirm the validity of those tyre models that include delay effects. A peculiar quasi-periodic oscillation detected during the experiments is explained by numerical simulations of the nonlinear time-delayed mathematical model.

A Modified Dugoff Tire Model for Combined-slip Forces

2010 ◽  
Vol 38 (3) ◽  
pp. 228-244 ◽  
Author(s):  
Nenggen Ding ◽  
Saied Taheri
Keyword(s):  
Vehicle Dynamics ◽  
Tire Model ◽  
Magic Formula ◽  
Model Based ◽  
Proposed Model ◽  
Road Friction ◽  
On Line ◽  
Double Lane Change ◽  
Tire Forces ◽  
Tire Models

Abstract Easy-to-use tire models for vehicle dynamics have been persistently studied for such applications as control design and model-based on-line estimation. This paper proposes a modified combined-slip tire model based on Dugoff tire. The proposed model takes emphasis on less time consumption for calculation and uses a minimum set of parameters to express tire forces. Modification of Dugoff tire model is made on two aspects: one is taking different tire/road friction coefficients for different magnitudes of slip and the other is employing the concept of friction ellipse. The proposed model is evaluated by comparison with the LuGre tire model. Although there are some discrepancies between the two models, the proposed combined-slip model is generally acceptable due to its simplicity and easiness to use. Extracting parameters from the coefficients of a Magic Formula tire model based on measured tire data, the proposed model is further evaluated by conducting a double lane change maneuver, and simulation results show that the trajectory using the proposed tire model is closer to that using the Magic Formula tire model than Dugoff tire model.

Influence of Gravity and Taper on the Vibration of a Standing Column

2012 ◽  
Vol 4 (04) ◽  
pp. 483-495 ◽  
Author(s):  
C. Y. Wang
Keyword(s):  
Cross Section ◽  
Numerical Stability ◽  
Natural Vibration ◽  
Vibration Frequencies ◽  
Stability Criteria ◽  
Initial Value ◽  
Vertical Column ◽  
Stability Boundaries ◽  
Section Shape ◽  
The Stability

AbstractThe stability and natural vibration of a standing tapered vertical column under its own weight are studied. Exact stability criteria are found for the pointy column and numerical stability boundaries are determined for the blunt tipped column. For vibrations we use an accurate, efficient initial value numerical method for the first three frequencies. Four kinds of columns with linear taper are considered. Both the taper and the cross section shape of the column have large influences on the vibration frequencies. It is found that gravity decreases the frequency while the degree of taper may increase or decrease frequency. Vibrations may occur in two different planes.

Non-Steady Planing and Advection Delay Effects on the Dynamics and Control of Supercavitating Vehicles

2011 ◽  
Author(s):  
Vincent Nguyen ◽  
Munther A. Hassouneh ◽  
Balakumar Balachandran ◽  
Eyad H. Abed
Keyword(s):  
Vehicle Dynamics ◽  
Underwater Vehicles ◽  
Cavitation Number ◽  
Delay Effect ◽  
Supercavitating Vehicles ◽  
Supercavitating Vehicle ◽  
Delay Effects ◽  
Dynamics And Control ◽  
Position And Orientation ◽  
And Control

Cavity-vehicle interactions play a significant role in the dynamics of supercavitating underwater vehicles. To date, in the vast majority of planing force models for supercavitating vehicle dynamics, a steady planing assumption is utilized, wherein the vehicle-cavity interaction is only dependent on the vehicle’s position relative to the cavity. In this work, a framework to properly account for the vehicle radial motions into and out of the fluid is presented. This effectively introduces damping or velocity related dependence into the planing force formulation. The planing force is applied to cavity sections that are described by a previous (or delayed) position and orientation of the cavitator. The physical basis for the advection delay and the expressions used to determine the vehicle immersion and immersion rate are presented. Analysis and simulations for the time-delayed, non-steady planing system are carried out, and the delay effect in this system is shown to be stabilizing for certain values of the cavitation number that is contrary to previous results that have assumed steady planing force models.

scholarly journals An Advanced Shell Theory Based Tire Model

2005 ◽  
Vol 33 (4) ◽  
pp. 227-238 ◽  
Author(s):  
D. Bozdog ◽  
W. W. Olson
Keyword(s):  
Vehicle Dynamics ◽  
Shell Theory ◽  
Finite Difference Methods ◽  
Integrated Approach ◽  
Tire Model ◽  
Element Analysis ◽  
Friction Forces ◽  
Dynamic Analyses ◽  
Tire Models ◽  
Elastic Substance

Abstract The objective of this paper is to investigate a class of general tire models that provides results suitable for usage in vehicle dynamics. Tire models currently used for vehicle dynamic analyses are overly simplistic (springs, a spring and damper combination or semi-elastic substance) or based on curve fits of experimental data. In contrast, the tire models used by major tire companies are extremely complex with solutions possible only by finite element analysis. Between these two extremes exists the potential for an elasticity based shell theory tire model. Micro-mechanics and composite laminate theories provide an integrated approach to the macroscopic behavior of the tire carcass and the tread support plies. This methodology has the capability of including centrifugal and friction forces. Finite difference methods are applied that produce reliable and accurate solutions of the tire response.

Symbolic Bifurcation Boundaries and Time-Dependent Resonance Sets of Time-Periodic Nonlinear Systems

1999 ◽  
Author(s):  
Eric A. Butcher ◽  
S. C. Sinha
Keyword(s):  
Nonlinear Systems ◽  
Parameter Space ◽  
Local Stability ◽  
Degree Of Freedom ◽  
Time Dependent ◽  
Periodic Systems ◽  
Stability Boundaries ◽  
System Parameters ◽  
Parameter Dependent ◽  
Time Periodic

Abstract A recent computational technique is utilized for symbolic computation of local stability boundaries and bifurcation surfaces for nonlinear multidimensional time-periodic dynamical systems as an explicit function of the system parameters. This is made possible by the recent development of a symbolic computational algorithm for approximating the parameter-dependent fundamental solution matrix of linear time-periodic systems. By evaluating this matrix at the end of the principal period, the parameter-dependent Floquet Transition Matrix (FTM), or the linear part of the Poincaré map, is obtained. The subsequent use of well-known criteria for the local stability and bifurcation conditions of equilibria and periodic solutions enables one to obtain the equations for the bifurcation surfaces in the parameter space as polynomials of the system parameters. Because this method is not based on expansion in terms of a small parameter, it can successfully be applied to periodic systems whose internal excitation is strong. In addition, the time-dependent normal forms and resonance sets for one and two degree-of-freedom time-periodic nonlinear systems are analyzed. For this purpose, the Liapunov-Floquet (L-F) transformation is employed which transforms the periodic variational equations into an equivalent form in which the linear system matrix is constant. Both quadratic and cubic nonlinearities are investigated, and all possible cases for the single degree-of-freedom case are studied. The above algorithm for computing stability boundaries may also be employed to compute the time-dependent resonance sets of zero measure in the parameter space. Two illustrative example problems, viz., a parametrically excited simple pendulum and a double inverted pendulum subjected to a periodic follower force, are included.

Nonlinear Free Vibration for Electromechanical Integrated Toroidal Drive

2012 ◽  
Vol 8 (2) ◽  
Author(s):  
Lizhong Xu ◽  
Fen Wang ◽  
Xiuhong Hao
Keyword(s):  
Operating Performance ◽  
Free Vibrations ◽  
Drive System ◽  
Vibration Frequencies ◽  
Mesh Stiffness ◽  
Nonlinear Free Vibration ◽  
System Parameters ◽  
Noise Radiation ◽  
Electromechanical Integrated ◽  
Electromechanical Coupled

Electromechanical integrated toroidal drive is an electromechanical coupled dynamics system. Here, the electromagnetic nonlinearity occurs which has important effects on the operating performance of the drive system. In this paper, the electromagnetic mesh stiffness is presented and nonlinear electromechanical coupled dynamic equations are deduced. Using the perturbation method, the nonlinear free vibrations of the drive system are investigated. Changes of the nonlinear vibration frequencies along with the system parameters are given. Results show that the electromagnetic nonlinearity has obvious effects on the vibration frequencies of the drive system. The results are useful in maximizing the power density of the drive system and reducing noise radiation.

Stability of a Rotor Partially Filled With a Viscous Incompressible Fluid

1979 ◽  
Vol 46 (4) ◽  
pp. 913-918 ◽  
Author(s):  
S. L. Hendricks ◽  
J. B. Morton
Keyword(s):  
Angular Velocity ◽  
Circular Cylinder ◽  
Incompressible Fluid ◽  
Parametric Study ◽  
Viscous Incompressible Fluid ◽  
Constant Angular Velocity ◽  
Unstable Region ◽  
Stability Boundaries ◽  
System Parameters ◽  
Linear Spring

A hollow circular cylinder rotating with constant angular velocity and partially filled with a viscous incompressible fluid has been analyzed for stability. The analysis can be extended to apply to many different rotor geometries. The results of this analysis predict that over a range of operating speeds, the system is unstable. The extent of this unstable region is determined by the system parameters. The interplay between viscosity of the fluid and damping on the rotor is especially important in determining stability boundaries. A parametric study is presented for a rotor modeled as a cup in the middle of a symmetrically supported massless shaft. The rotor is subject to a linear spring and a linear damper. Rotor unbalance, gravity, and axial effects are considered negligible.

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