For modeling an aircraft tire using the brush model method, the friction coefficient µbetween rubber and asphalt should not only be described in terms of the applied pressure and sliding velocity/slip ratio, but also by local temperature inside the contact area. Its influence cannot be neglected as it leads to significant changes in the material properties. Therefore investigations on different test rigs are analyzed using thermal recordings of an infrared camera.

First measurements are done on HiLiTe (High Speed Linear Tester), a test rig at the Institute of Dynamics and Vibration Research (IDS) at Leibniz University Hanover, Germany. It allows testing single tread block samples on a variety of surfaces such as dry and wet asphalt or concrete, as well as on snow and ice with a constant slip ratio of 100%, i.e. pure sliding.

Results in this paper show that the convection has a lesser impact on the tread block cooling than the actual contact between runway surface and sample. Since colder surface temperatures lead to higher friction this effect is antagonizing the excitation frequency which heats up the rubber sample at high velocities. On long lasting test sequences a quasi-steady friction coefficient might be achieved once these effects start to converge. Still, due to permanent slip the abrasion leads to cooling as the hot top layer of the rubber is removed occasionally.

In addition to these quasi-steady measurements on HiLiTe the thermal behavior of an aircraft tire is investigated with an autonomously running test rig. It allows realistic testing on an airfield runway by altering load, speed and slip-angle of the tire within and beyond the regions of a passenger aircraft. During the measurements new and partially unknown effects could be observed. The temperature is mostly influenced by the slip-angle followed by speed and load. Furthermore the contact between tire and runway leads to cooling of the tread but does not affect the temperature inside the grooves. They heat up separately and tend to deliver heat to the tread if the cooling by the runway becomes too low.