Editorial Type:
Article Category: Research Article
 | 
Online Publication Date: 01 Oct 2015

Self-Excited Torsional Oscillations under Locked-Wheel Braking: Analysis and Experiments

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Page Range: 276 – 296
DOI: 10.2346/tire.15.430402
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ABSTRACT

This paper analyzes the effect of tire/vehicle parameters, specifically of tire/suspension torsional stiffnesses, on the stability of self-excited tire torsional oscillations during locked-wheel braking events. Using a torsionally flexible tire-wheel model and a dynamic tire-ground friction model, two system models for tire oscillations are considered: with suspension torsional compliance included in one but excluded in the other. Bifurcation analysis is conducted on both systems to derive the effect of tire/vehicle parameters on the stability. For the system without suspension torsional compliance, it is highlighted that the primary cause of unstable self-excited oscillations is the “Stribeck” effect in tire-ground friction. Based on the parameters obtained experimentally, the bifurcation surface of vehicle velocity with respect to tire/suspension torsional stiffness is also given. The effect of tire/suspension torsional stiffness to the stability of tire torsional oscillation is qualitatively validated via comparisons between locked-wheel braking simulations and experiments with tires with different torsional stiffnesses.

Keywords: stability analysis, bifurcation analysis, tire torsional oscillation, tire/suspension torsional stiffness
FIG. 1
FIG. 1

Flexible sidewall tire model.

FIG. 2
FIG. 2

Flexible sidewall tire supported on a torsional flexible suspension.

FIG. 3
FIG. 3

Steady state μ-slip curves by LuGre model.

FIG. 4
FIG. 4

Bifurcation curve in vv–KT plane and comparison between systems with/without suspension torsional flexibility.

FIG. 5
FIG. 5

Bifurcation surface of vv due to KST and KT.

FIG. 6
FIG. 6

Ring oscillation measurement.

FIG. 7
FIG. 7

Measured wheel speed θॱw and dynamometer speed vdyno.

FIG. 8
FIG. 8

Nonlinear torsional stiffness of tire 2.

FIG. 9
FIG. 9

Measured and fitted oscillation signals for tire 2.

FIG. 10
FIG. 10

Comparison between test data and simulation results for tire 2.

FIG. 11
FIG. 11

Comparison between test data and simulation results for tire 1.

Contributor Notes

1 Corresponding author. Clemson University, International Center for Automotive Research, 4 Research Drive, CGEC, Greenville, South Carolina, 29607, USA. Email: chunjiw@clemson.edu
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