Editorial Type:
Article Category: Research Article
 | 
Online Publication Date: 01 Mar 2012

Investigation of Friction Mechanisms of Siped Tire Tread Blocks on Snowy and Icy Surfaces

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Page Range: 1 – 24
DOI: 10.2346/1.3684409
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Abstract

REFERENCE: S. Ripka, H. Lind, M. Wangenheim, J. Wallaschek, K. Wiese, and B. Wies “Investigation of Friction Mechanisms of Siped Tire Tread Blocks on Snowy and Icy Surfaces,” Tire Science and Technology, TSTCA, Vol. 40, No. 1, January–March 2012, pp. 1–24.

ABSTRACT: Due to general safety reasons and an increasing individual demand on more traffic safety, winter tires have become more and more important. This evolution results in a rising requirement of the customers concerning the tire performance on the one hand, and the effort of the tire industry to improve the tire traction performance on snow and ice on the other hand. To engineer winter tires in an effective way, the friction influencing factors as well as the contact mechanics should be well known. Normally the design and development of tires is strongly based on vehicle tests, but in modern tire development processes the simulation as well as the experimental investigation of tires and tire components in the lab have become more popular. This strategy plays an especially important role for reducing the time of development cycles but also the development costs. With simulation and experiments in lab, new challenges come up which have to be solved. Lab experiments compete with totally different problems: First of all, the environmental influences like temperature and humidity have to be controlled. Furthermore, the test tracks used inside must be comparable to the proving ground outside, hence the properties of snow and ice have to be investigated in detail. Therefore not only is it very important to understand the formation of snow and ice, but also to find characteristics of both materials which can be identified and measured with mobile measurement devices outside on the test track and inside in the lab. Within this publication a general overview of the tire tread block test method as well as the test rig, which are used for identifying relevant tread block friction mechanisms on snow and ice, will be given. The results of the measurement will be shown and the acting friction phenomena will be explained.

Keywords: rubber; tire tread block; friction; friction mechanisms; snow; ice
Copyright: The Tire Society
FIG. 1.
FIG. 1.

Accident probability depending on road conditions [15].

FIG. 2.
FIG. 2.

Digging of tread blocks into the snow (according to Ref. [3]).

FIG. 3.
FIG. 3.

Friction theory of SCHRAMM et al.: Stationary heat flow for a differential element of the generated water layer (according to Ref. [12]).

FIG. 4.
FIG. 4.

Range of results of Continental outdoor tire traction test with siped tread pattern (Average of results of different days and several measurements per day).

FIG. 5.
FIG. 5.

Range of results of Continental outdoor tire traction test with siped tread pattern (average of several results of one day).

FIG. 6.
FIG. 6.

Passenger car test outdoor: Influence of the number of sipes of a winter tire on ice friction.

FIG. 7.
FIG. 7.

Sticking and sliding areas within a tire footprint depending on slip [15].

FIG. 8.
FIG. 8.

(a) High speed linear test rig HiLiTe. (b) Carriage of HiLiTe.

FIG. 9.
FIG. 9.

Tread block samples (a) non siped block (G0), (b) three siped tread block (G3).

FIG. 10.
FIG. 10.

Steady state evaluation of HiLiTe measurements.

FIG. 11.
FIG. 11.

Steady state friction characteristic of a tire tread block measured with HiLiTe (Depending on sliding velocity, normal pressure and ambient temperature).

FIG. 12.
FIG. 12.

Unsteady measurement: Velocity sweep.

FIG. 13.
FIG. 13.

Comparision of steady state and unsteady evaluation of HiLiTe measurements.

FIG. 14.
FIG. 14.

Comparison of frictional properties of natural versus in-house produced snow.

FIG. 15.
FIG. 15.

Evaluation of the influence of the tread compound on the ice friction process.

FIG. 16.
FIG. 16.

Evaluation of the influence of the tread pattern (siped and nonsiped, cp Fig. 11) on the ice friction process at HiLiTe.

FIG. 17.
FIG. 17.

Flexible tread block holder.

FIG. 18.
FIG. 18.

Investigation of the influence of the block element length l.

FIG. 19.
FIG. 19.

Investigation of the influence of the fixing method: (a) Blocked element, (b) Clamped block element, (c) Velocity depending friction characteristic.

FIG. 20.
FIG. 20.

(a) Tread block-ice contact with “dry” run-in area ɛ, (b) Temperature distribution under sliding tire tread block, (c) Shear force distribution under sliding tread block.

FIG. 21.
FIG. 21.

Influence of temperature, normal pressure and sliding velocity on the length of the “dry” run-in area ɛ.

FIG. 22.
FIG. 22.

Level of friction force depending on tread block element length.

FIG. 23.
FIG. 23.

Analyzing the contact area during sliding on ice: (a) Test set up, (b) Contact area of blocked (grey) and clamped (black) sample.

FIG. 24.
FIG. 24.

(a) Calculated local pressure depending friction characteristic. (b) Measured nominal pressure depending friction characteristic of nonsiped tread block sample.

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