A large number of models for real contact area calculation of tribological applications are known from literature. Greenwood and Williamson (GW) model, which is based on the Hertz contact theory, is one of the most famous classical model. It assumes that a rough surface consists of asperity peaks having ideal spherical tips with the same radius, and also showing statistical height distribution. In this study, 2D profilometry measurements and GW model were used to determine the real contact area of brake pads. Results of the classical approach were compared with those obtained using an alternative method to estimate morphological surface parameters. The proposed method allows a quick characterization of a large area of brake pad surface. It is based on image segmentation technique, which is applied to the micrographs of the material surfaces by appropriate image analyzer software. Through this technique, it is estimated the number of contact plateaus and total contact plateaus areas. The image segmentation technique proved to be adequate for investigating morphological aspects of friction materials, providing complementary information to those obtained with GW model.

Masotti, Diego*;Antunes, Diego SeveroFras-le, Brazil; Gomes, Kássio; Ferreira, Ney; Neis, Patric; Federal University of Rio Grande do Sul, Brazil