Tuning of Friction Oscillation Amplitude in Halloysite, Montmorillonite, and Wollastonite Filled Friction Composites: Load, Speed, and Temperature Sensitivity

The influence of clay mineral silicate types, such as halloysite, montmorillonite, and wollastonite with tubular, plate like, and acicular morphologies respectively, on frictional oscillation of composite materials have been evaluated on Chase type dynamometer and optimised following the combination of Taguchi's L9 design of experiment and regression analysis approaches. The coefficient of friction of ~0.35-0.45 and cumulative wear at < 10 % remained well within the acceptable range. The optimal tuning of friction oscillation to reduce braking induced noise and vibration propensity has been achieved by montmorillonite clay with platelet type morphology or by combination of MgO and wollastonite clay with acicular morphology. The extent of Fe- content in wear debris close to ~ 80 % on the composite surface led to an optimal level of friction oscillation amplitude (Aamp). The hierarchical ranking of the clay based composites by TOPSIS based operation research approach lead to the understanding of design ideology optimization for composites to ensure minimal friction oscillations.

Effects of External Hard Particles on Brake Friction Characteristics During Hard Braking

The effects of external hard particles on the friction coefficients and its oscillation amplitudes during hard braking were investigated. Silica sands of the size between 180 to 355 μm were used during the experiments. The results were compared to the results obtained without the grit particles present in order to determine the change in friction coefficient and the fluctuation of frictional oscillation amplitude. Different sliding speeds were applied and external hard particle of different size is found to significantly affect the friction coefficient and standard deviation of friction oscillation amplitude values. The friction coefficients increase with hard particle due to the rapid changes of the effective contact area and the abrasion mode. Some embedded particles operating in two body abrasion mode help to increase the disc surface roughness and influence the stopping time of the disc. The standard deviation values of friction oscillation amplitude however were stable due to more wear debris produced and get compacted to form friction films assisting friction and they tend to reduce at medium speeds because many contact plateaus and effective contact area started to stabilize.

Effects of External Hard Particles on Brake Friction Characteristics During Hard Braking

The effects of external hard particles on the friction coefficients and its oscillation amplitudes during hard braking were investigated. Silica sands of the size between 180 to 355 μm were used during the experiments. The results were compared to the results obtained without the grit particles present in order to determine the change in friction coefficient and the fluctuation of frictional oscillation amplitude. Different sliding speeds were applied and external hard particle of different size is found to significantly affect the friction coefficient and standard deviation of friction oscillation amplitude values. The friction coefficients increase with hard particle due to the rapid changes of the effective contact area and the abrasion mode. Some embedded particles operating in two body abrasion mode help to increase the disc surface roughness and influence the stopping time of the disc. The standard deviation values of friction oscillation amplitude however were stable due to more wear debris produced and get compacted to form friction films assisting friction and they tend to reduce at medium speeds because many contact plateaus and effective contact area started to stabilize.