FRICTION COEFFICIENTS BETWEEN TIRES AND PAVEMENTS SURFACES

Abstract : It was found that low friction coefficients were responsible for some aircraft accidents on naval airfields. Basic studies indicated that the actual friction coefficients between tires and pavement surfaces did not follow the basic laws of friction. The total frictional force included, in addition to the basic frictional force, a mechanical force resulting from the interlocking of the rubber with the aggregate particles protruding above the pavement surfaces. Various field-testing devices, developed by others, were used and compared in an effort to locate low-friction pavements and to standardize the method of measurement. One device still in the development stage showed promise of measuring friction coefficient under simulated conditions of landing aircraft. Many factors affecting the friction coefficient between tires and pavement surfaces were found through laboratory and field investigations. These factors were related to vehicle and aircraft operation, to tire design, and to types of pavement surfaces. The effect of these factors on the friction coefficients were varied. The individual effects of each factor were not found since many of the factors worked in combination.