Evaluation of temperature effects on brake wear particles using clustered heatmaps

Abstract

Temperature effects on the generation of brake wear particles from railway vehicles were generated, with a particular focus on the generation of ultrafine particles. A real scale brake dynamometer test was repeated five times under low and high initial temperatures of brake discs, respectively, to obtain generalized results. Size distributions and temporal patterns of wear particles were analyzed through visualization using clustered heatmaps. Our results indicate that high initial temperature conditions promote the generation of ultrafine particles. While particle concentration peaked within the range of fine sized particles under both low and high initial temperature, an additional peak occurred within the range of ultrafine sized particles only under high initial temperature. The timing of peak occurrence also differed between low and high initial temperature conditions. Under low initial temperature fine sized particles were generated intensively at the latter end of braking, whereas under high initial temperature both fine and ultrafine particles were generated more dispersedly along the braking period. The clustered correlation heatmap divided particle sizes into two groups, within which generation timing and concentration of particles were similar. The cutoff point between the two groups was approximately 100 nm, confirming that the governing mechanisms for the generation of fine particles and ultrafine particles are different.

Representativeness of airborne brake wear emission for the automotive industry: A review

“…For this reason, the most researchers are investigating the braking particles with a dyno. 23,24,29,41,42 In a dynamometer, real braking materials are used. A disc rotates with set inertia, representing the mass of the vehicle simulated.…”

“…Temperature has a clear impact on brake emission. 3,16,30,40,42 Friction in braking systems is a strong source of thermal energy. Therefore, discs are so designed to ensure their viability.…”

“…This discrepancy indeed could influence the emission rate, but it also changes the whole air flow, by increasing the turbulence intensity. 31,42,48…”