FRACTAL CHARACTERIZATION OF ROAD SURFACE TEXTURES FOR ANALYSIS OF FRICTION

In this paper work performed at the Pennsylvania Transportation Institute at the Pennsylvania State University and at the Norsemeter Corp Norway is described and given in two parts. Firstly, in the studies of tire-road surface interface and vehicle safety, three different scales (ranges) have been used to describe surface texture (micro- macro- and mega-texture). One goal of the present paper is to show the achievability of a scale-independent surface description of surface texture. A short review of fractal geometry is given in the first part of the paper together with the description of a developed fractal texture model of pavement surfaces. Secondly, the development of a stochastic-viscoelastic contact model is presented: the model was designed to provide a qualitative and quantitative texture-friction description. This part provides a comprehensive study of the texture-friction phenomena with a strong physical foundation. The new microcontact model developed was based on a multiscale description of fractaloid rough surfaces and viscoelastic properties of the tire. The model led to the calculation of the real area of contact and the relationship of the real area of contact and the friction coefficient-slip speed curve was then explored. (a) For the covering entry of this conference, please see IRRD abstract no. 878344.