INFLUENCE OF THE ROAD-SURFACE TEXTURE ON THE SPEED DEPENDENCY OF TIRE / ROAD FRICTION
Tire/wet road friction depends on two road-surface texture scales: the macrotexture (centimeterto millimeter dimensions) is responsible for the speed dependency of friction, and the microtexture (submillimeter dimensions) is responsible for the friction level at any speed. This paper deals firstly with the description of road-microtexture, the macrotexture scale being well documented. Considering the fact that rubber energy-loss controls tire/wet road friction and that angularity of road-surface asperities influences greatly tire deformation, the second author has proposed a description method derived from the motif-combination technique. This method defines two parameters related to the sharpness of asperity summits and the relative position of these summits. A model has been then proposed by the first author to describe the friction-speed curve from roadsurface macroand microtexture descriptors, tire-related characteristics (rubber properties, wear) and road wetness. The description is based on the Stribeck curve. The speed-dependency friction model is applied to the analysis of car-braking tests. Comparisons between calculated and measured friction-coefficients at different braking speeds are presented and discussed.
Frottement pneumatique / chaussée influence de la microtexture des surfaces de chaussée
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Frottement Pneumatique / Chaussée – Influence de la microtexture des surfaces de chaussée Minh Tan Do, Hassan Zahouani
PREDICTION OF TIRE-ROAD FRICTION FROM TEXTURE MEASUREMENTS
A purely theoretical means for predicting tire-road friction has been the subject of research for the past two decades. It is based on a faithful simulation of a pneumatic tire sliding over the wet texture of the road surface. This involved the stress-gross strain analysis of the tread rubber, the effect of shear rate, heat, and lubrication. A device called the Yandell-Mee texture friction meter is described and is the end product of this research. When placed on a road surface, it samples a total texture profile 60 cm long to an accuracy of 0.05 mm and predicts side force and locked-wheel wet friction for three speeds in seconds. Because the result varies only with texture changes, this is an excellent control tool for pavement engineers.