Finite Element Framework for the Computation of Runway Friction of Aircraft Tires

Safe runway operations are an important consideration and challenge for airport authorities. Investigations have shown that runway friction is greatly reduced during wet weather operations. Any traction failure during high-speed landing and take off of an aircraft could lead to accidents and loss of human life. In practice, runway friction is estimated with a ground vehicle, such as continuous friction measuring equipment equipped with a Pavement International Association of Road Congress (PIARC) tire. Recommendations for safe runway friction are based on statistical correlations between such devices and aircraft tires. However, such correlations do not incorporate the variability of the field conditions to the test condition. This paper presents an approach that uses a three-dimensional finite element (FE) model capable of simulating a rolling aircraft tire at any given operating conditions. The highlight of the approach is the consideration of FE meshes of asphalt surfaces rather than artificial surfaces. The model was used to determine the effect of aircraft tire operating conditions on runway friction. The trends of results predicted by the model agree with the previous experimental studies on aircraft tires. It was also found that the computed wet friction of a PIARC tire and an aircraft tire are different, particularly for the extreme operating conditions of tire inflation pressure and water depth. This result indicates that an intrinsic variability exists between the friction coefficients of an aircraft tire and a PIARC tire.