Sliding friction acoustics

Contact interactions generate acoustic energy in complicated ways, dictated by dozens of system parameters. The ability to accurately predict these stochastic friction forces and resultant acoustic energy from first principles is currently lacking. A summary of experimental tests with sliding and stick-slip of metal-on-metal contact are presented to provide insight into the influence of roughness, sliding velocity, and normal load on the generated acoustics. Normal load and normal displacement increase in dynamic amplitude under stick-slip conditions relative to smooth sliding. In the current configuration, stick-slip also produces an excess of up to 30 dB SPL, relative to smooth sliding. Relationships between normal load, surface roughness, tangential velocity, and acoustic output are explored, and parameters are tuned to fit these variables using an existing empirical relationship from the literature.