Caracteriza o da tenacidade à fratura de materiais de fric o e critérios de projetos

The purpose of this study was to characterize friction materials currently used in heavy vehicles for assembly lines and replacement parts. Five different friction materials were evaluated through mechanical tests based on the ASTM D5045-99 (Reapproved 2007) Standard - Plane Strain Fracture Toughness and Strain Energy Release Rate of Plastic Materials. Results of KIC for the five materials were on the order 1 MPa.m1/2, corroborating values expected for phenolic matrix materials. In addition, KIC results are representative of the fragility of friction materials. A statistical analysis was conducted using the Weibull methodology, allowing to establish occurrence probabilities of KIC lower than a randomly chosen value. Consequently, from a design point of view, it is possible to establish failure criteria and avoid investing resources in prototypes that may come to fail in field tests.