Editorial Type:
Article Category: Research Article
 | 
Online Publication Date: 01 Mar 2008

Ultrasonic Measurements of Contact Area and Pressure Distribution of a Pneumatic Tire on a Rigid Surface3

,
, and
Page Range: 43 – 62
DOI: 10.2346/1.2804126
Save
Download PDF

Abstract

Contact phenomena which occur at the tire-ground interface play a crucial role in most issues related to optimal performances of the vehicle, safety, comfort, and energy consumption. Thus, it is essential to have available experimental tools capable of supplying detailed information about the main contact parameters (size and shape of nominal contact area and contact pressure distribution), especially when unknown or unpredictable external conditions make it difficult to use numerical tools in assessing them. Although a number of laboratory techniques have been devised to address this problem, here we propose a novel approach that exploits the property of ultrasonic waves to be differently reflected by a contact interface depending on its stress state. This noninvasive method is capable of supplying in real-time detailed maps of contact conditions as well as quantitative information with regard to geometric features of the contact area and contact pressure distribution values after suitable postprocessing procedures.

This study reports the results of the application of the ultrasonic method in the case of contact of a motor-bicycle tire on a rigid surface. A number of tests were carried out under different conditions with regard to inflation pressure and applied load. In each case, the raw reflection data were converted into graphic maps that display the contact area features and contain information about contact pressure. Moreover, to assess the quantitative reliability of the technique, ultrasonic data were compared with those obtained by means of a commercial pressure-sensitive film. The results are discussed to evaluate the capability of the ultrasonic method to correctly capture contact patch features.

Keywords: tire; contact; experimental; ultrasonic analysis; contact area; contact pressure
Copyright: The Tire Society
FIG. 1.
FIG. 1.

Tire-plate contact: (left) arrangement of the components for the ultrasonic analysis and (right) tire tread pattern.

FIG. 2.
FIG. 2.

Schematic representation of the experimental setup for the ultrasonic tests.

FIG. 3.
FIG. 3.

Diagram of the procedure to convert pressure-sensitive film results into contact pressure maps.

FIG. 4.
FIG. 4.

Diagram of the procedure to obtain nominal contact area values from pressure-sensitive film tests.

FIG. 5.
FIG. 5.

Graphic processing of ultrasonic refection data for a tire–plate contact (applied load 600 N, inflation pressure 250 kPa).

FIG. 6.
FIG. 6.

Ultrasonic maps of contact: evolution of the contact ellipse for increasing applied loads (inflation pressure 250 kPa).

FIG. 7.
FIG. 7.

Ultrasonic maps of contact, evolution of the contact ellipse for decreasing inflation pressures (applied load 1000 N). (Bottom) Magnification of a detail of the results. The granular nature of the film appears evident.

FIG. 8.
FIG. 8.

Evolution of the contact ellipse for increasing applied loads as obtained from the pressure-sensitive film tests (inflation pressure 250 kPa).

FIG. 9.
FIG. 9.

Evolution of the contact ellipse for decreasing inflation pressures as obtained from the pressure-sensitive film tests (applied load 1000 N).

FIG. 10.
FIG. 10.

Trend of the nominal contact area (pressure-sensitive film).

FIG. 11.
FIG. 11.

Comparison between the contact area values obtained from ultrasonic and those from pressure-sensitive film tests.

FIG. 12.
FIG. 12.

Comparison between the contact pressure profiles (transversal direction) obtained from ultrasonic and pressure-sensitive film tests (600 N load, 250 kPa inflation pressure).

  • Download PDF