Editorial Type:
Article Category: Research Article
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Online Publication Date: 01 Dec 2006

Contact Analysis of Tire Tread Rubber on Flat Surface with Microscopic Roughness3

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Page Range: 237 – 255
DOI: 10.2346/1.2346375
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Abstract

This paper describes experimental and analytical studies of the dependence of tire friction on the surface roughness of pavement. Abrasive papers were adopted as representative of the microscopic surface roughness of pavement surfaces. The rolling∕sliding friction of tire tread rubber against these abrasive papers were measured at low slip velocities. Experimental results indicated that rolling∕sliding frictional characteristics depended on the surface roughness. In order to examine the interfacial phenomena between rubber and the abrasive papers, real contact length, partial slip, and apparent friction coefficient under vertical load and tangential force were analyzed with two-dimensional explicit finite element analysis in which slip-velocity-dependent frictional coefficients were considered. Finite element method results indicated that the sum of real contact area and local partial slip were larger for finer surfaces under the same normal and tangential forces. In addition, the velocity-dependent friction enhanced local slip, where the dependence of local slip on surface roughness was pronounced. It proved that rolling∕sliding friction at low slip ratio was affected by local frictional behavior at microslip regions at asperity contacts.

Keywords: friction; rolling∕sliding contact; surface roughness; tire tread rubber; FEM
Copyright: The Tire Society
FIG. 1.
FIG. 1.

Roughness and traction measurement system.

FIG. 2.
FIG. 2.

Surface profiles of abrasive papers.

FIG. 3.
FIG. 3.

Comparison between magic formula interpolation and experimental data (B=4.79, C=1.65, D=1.86, E=0.66).

FIG. 4.
FIG. 4.

(a) Effect of surface roughness on the friction coefficient. (b) Effect of surface roughness on the friction coefficient; slip ratio from 0 to 0.2.

FIG. 5.
FIG. 5.

Slip-velocity-dependent frictional coefficients (exponential decay friction coefficient; μs=1.0, μk=0.2, d=0.001).

FIG. 6.
FIG. 6.

Rolling∕sliding and static tangential loading.

FIG. 7.
FIG. 7.

Deformed shape of rubber surface in contact with abrasive paper A120 with vertical load of 2.46 N and tangential force of 1.36 N.

FIG. 8.
FIG. 8.

Changes in real contact length with vertical load (μs=μk=1.0).

FIG. 9.
FIG. 9.

Changes in real contact length with tangential force under constant vertical load of 2.46 N (μs=μk=1.0).

FIG. 10.
FIG. 10.

Changes in real contact length with vertical load (μs=1.0, μk=0.2, d=0.001).

FIG. 11.
FIG. 11.

Changes in real contact length with tangential force under constant vertical load of 2.46 N (μs=1.0, μk=0.2, d=0.001).

FIG. 12.
FIG. 12.

Variation of NS∕NC with tangential force (μs=μk=1.0).

FIG. 13.
FIG. 13.

Average slip at parts of the contact patch under tangential force of 1.4 N (μs=μk=1.0).

FIG. 14.
FIG. 14.

Variation of NS∕NC with tangential force (μs=1.0, μk=0.2, d=0.001).

FIG. 15.
FIG. 15.

Average slip at parts of the contact patch under tangential force of 1.4 N (μs=1.0, μk=0.2, d=0.001).

FIG. 16.
FIG. 16.

Variation of friction coefficient with NS∕NC (μs=μk=1.0).

FIG. 17.
FIG. 17.

Variation of friction coefficient with NS∕NC (μs=1.0, μk=0.2, d=0.001).

FIG. 18.
FIG. 18.

(a) Deformed shape and minimum principal stress of rubber surface in contact with asperity of A120 with vertical load of 2.46 N. (b) Deformed shape and minimum principal stress of rubber surface in contact with asperity of A120 with vertical load of 2.46 N and tangential force of 1.54 N.

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