ETUDE NUMERIQUE ET EXPERIMENTALE DU COMPORTEMENT TRIBOLOGIQUE DES CONTACTS GLISSANT - Application aux freins à disques

Abstract

Understanding the physical mechanisms resulting from dry sliding contact disc / pads, require an experimental simulation represented by a disc and a pin, under the influence of a number of braking parameters, such as the nature of the disc material and pin, the load applied by the pin in,and the rotational speed of the disc. On the other hand to apprehend the evolution of the tribological behaviour of braking materials, it is a critic to understand the answer of the brake disc materials in them environments especially in the littoral environment where humidity and salinity rate are very high. However the corrosion of the contact emerges because these environments have a large effect on the friction coefficient and the wear of the brake discs materials.For that purpose,a friction experimental model was carried out by means a tribometer disc-on-pin (SRV4, Optimal Instruments Germany), using as disc brake materials: cast iron (FG25), chromium steel (100Cr6) and an aluminum-based composite Al-MMC (A359/SiC ). The pins in all tests were in friction materials, an organic resin-based brake pads material used in automotive Fabia Skoda 1.4, and a composite semi-metallic brakes pads equipped a transport aircraft. The experimental results showed that friction coefficients and the wear rate for all materials were insensitive to increasing normal load and sliding speed.By increasing humidity it observed a formation of water films which behaved as a lubricant at the sliding interface and reduced the friction coefficient and the wear rate. The corrosion due to salt spray had a larger influence on the tribological behaviour of the cast iron and the chromium steel than it did.The numerical investigation offers significant results as those measured by the tribometer. The Al MMC A359/SiC exhibited a better tribological behavior than the other brake disc materials used in this investigation under the given test conditions.