Behavior and Mechanism of Evolution on Friction-Induced Vibration of Phenolic Resin-Based Friction Material

Severe friction-induced vibration is prone to occur in phenolic composite/metal pairs during long-term tribological service, while high-frequency noise is radiated, leading to equipment shutdown or even damage. The mechanism of friction vibration noise generation is relatively complex and has not yet been clearly explained in physics. In response to the friction-induced vibration behavior of phenolic resin composite, the reciprocating tribology tests consisting of phenolic composite/ductile iron friction pairs were designed. During the tribology tests, the friction force and vibration signals were collected and analyzed. To avoid interference with the friction system, a non-contact high-precision vibration measurement system based on Laser Doppler Velocimetry was used. The test results showed that vibrations at 80 Hz and 800 Hz gradually appeared, coinciding with its natural frequencies. Furthermore, the comparative analysis was conducted on the surface morphology of phenolic composite/metal pair before and after wear. The results indicated that the surface roughness significantly decreased after tribology test. The decrease in surface roughness was due to the continuous wear and material transfer of phenolic composite, resulting in the formation of transfer films with lower surface roughness. A lower surface roughness implied a larger real contact area, leading to further exacerbation of adhesive wear. Compared to abrasive wear, adhesive wear was more likely to induce higher-frequency interface vibration. By conducting a comprehensive analysis of periodic frictional force, vibration signal, wear surface morphology, and velocity dependence, the "stick-slip" behavior in the friction process was proposed as a key factor inducing frictional vibration and noise generation and evolution. The friction-induced vibration of phenolic composite /metal pair was generated by the unstable excitation during the "stick-slip" process on the moving interface. Essentially, it was caused by the transmission and superposition of high-frequency stress waves generated by interactions of friction pair during the "slip" stage, which excited vibrations in the system at its natural frequency. During the "slip" stage, tangential interactions between relative moving interfaces mainly arose from adhesive and detachment behaviors at the friction interface and mechanical behaviors such as contact and collision between rough peaks. In the friction process of phenolic composite/metal pair, as a smooth transfer film forms gradually increasing real contact area, the dominant mechanism for wear transitioned from abrasive wear to adhesive wear. The frequency of vibrations produced at the friction interface increased accordingly to approach or match with high-frequency natural frequencies of the friction system, thereby inducing high-frequency vibration of system. This study elaborated on the generation and evolution of friction-induced vibration of phenolic composite, providing a theoretical reference for suppressing vibration noise by controlling interface excitation in the friction system.