Resin-based composites are extensively used in various braking systems due to their stable and sufficient coefficient of kinetic friction, good wear resistance, high yield, and low energy consumption. However, aside from their benefits, they can generate environmental noise pollution while undergoing friction. In this study, we investigated the relationship between the tribological properties of phenolic resin-based composites and their friction noise characteristics. Using the finite element analysis method, we deeply analyzed the connection between friction noise and unstable vibration of the friction interface, revealing the underlying mechanism of friction noise. Additionally, we conducted experiments to examine the tribological properties and friction noise behavior of phenolic resin-based composites under various temperature conditions.
With the increase in rotational speed, a significant amount of heat generated by friction results in a quick rise in the temperature of the friction interface. The composite binder became soft, generating a considerable amount of abrasive debris accumulation, which then further promoted the formation of adhesive wear. The fluctuation of friction became increasingly apparent, detrimentally impacting the stability of the contact interface and causing a significant increase in effective sound pressure levels of frictional noise. In instances where the normal load was minimal, the contact pressure at the friction interface was also small. As a result, the shear adhesion between the micro-convex bodies was weak, leading to less energy being fed into the system, ultimately reducing the occurrence of frictional fluctuation and limiting the noise sound pressure level. When the normal load reached a certain threshold, abrasive debris produced by wear creates a fresh contact platform at the friction interface. This mitigated the wear on the friction interface to a certain extent, while also moderating and reducing the energy of frictional fluctuations. This led to a significant decrease in the frictional fluctuation coefficient and effective sound pressure level of the noise. Temperature was a significant factor influencing the tribological properties of phenolic resin-based composites. This paper investigated the influence of temperature on the friction characteristics and noise. The results indicated that with increasing test temperature, the phenolic resin transitions from a glassy state to a highly elastic one, accompanied by a significant reduction in energy storage modulus and an increase in the number of microconvex bodies at the contact interface. The micro-convex bodies' strong interaction caused unstable vibration and noise radiation of the friction interface. The temperature correlated positively with the friction coefficient fluctuation and the effective sound pressure level of the friction noise. Through the finite element analysis technique, it was apparent that the unstable vibration frequency of the pinned specimen and the friction noise frequency were in proximity to one another; the maximum error of the unstable vibration frequency was 5.90% and 10.07%, correspondingly. The vibration outcomes of the friction interface with its noise results showed a beneficial agreement, thus leading us to conclude that the friction noise was closely related to the friction-induced unstable vibration at the contact interface.
In this paper, a combination of experimental and simulation methods was used to investigate the influence of the friction characteristic parameters of resin-based friction materials on the effective sound pressure level of friction noise under different test conditions, and the mechanism of friction noise generation was reasonably explained. The friction noise was closely related to the test conditions, and changes in the test conditions would affect the unstable vibration state of the contact interface and thus change the friction noise level. The friction noise was positively correlated with the relative sliding speed and temperature, and increased and then decreased with the increase of normal load.
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