Analysis of the error in the estimation of the morphology of contact plateaus existing on the surface of brake pads

The present paper provides a statistical analysis of the error obtained in the measurement of density (Dcp), size (Scp) and area fraction (Acp) of the contact plateaus existing on the surface of brake friction materials (BFM). Two different analysis were performed: (1) random: micrographs were taken in random locations of the BFMs' surfaces; (2) deterministic: micrographs were taken in 3 arrangements, that are border (B), center (C) and distributed (D). Results of the random analysis revealed that a micrograph area of 43.6 mm2 (12 images) provides an error lower than 5% for all the 3 morphological parameters studied. Deterministic analysis showed that arrangement D provides the lowest error in Acp, while B and C are prone to generate biased errors.