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This paper presents a numerical simulation of an aircraft tire in contact with a rough surface using a variable friction coefficient dependent on temperature and contact pressure. A sliding facility was used in order to evaluate this dependence of the friction coefficient. The temperature diffusion throughout the tire cross-section was measured by means of thermocouples. Both frictional heating and temperature diffusion were compared to numerical two-and three-dimensional simulations. An adequate temperature prediction could be obtained. In future simulations, wear should be taken into account in order to have a more accurate simulation especially in the case of high pressures and slipping velocities. A 3D finite element model for a rolling tire at a velocity of 37.79 knots (19.44 m/s) and in a cornering phase was investigated using a variable friction coefficient dependent on temperature and pressure. The numerical simulation tended to predict the temperature of the tire tread after a few seconds of rolling in skidding position, the temperature of the contact zone increases to 140 • C. Further investigations must be carried out in order to obtain the evolution of the temperature observed experimentally. The authors would like to point out that for confidentiality reasons, certain numerical data could not be revealed.

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.

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In many fields of technical and non-technical applications occur friction induced vibrations. If undesired, which applies to most of these oscillations, different methods exist for their avoidance or at least reduction. A recently investigated method, the systematic treatment of contacting surfaces by different techniques is shown in this work with the example of a pneumatic seal.