Gear teeth impacts in hydrodynamic conjunctions: Idle rattle

In the last decade, idle rattle in automotive transmissions has become a major concern in powertrain engineering. Palliative methods such as the Dual Mass Flywheel (DMF) have produced encouraging results in attenuating gear rattle with high cost implications. Fundamental and economic solutions can only source from root cause investigations. This paper introduces a new approach to study gear rattle from a tribo-impact perspective; gear impacts causing rattle are treated as lubricated conjunctions rather than following the conventional assumption of dry contacts. It was found that depending on the forcing conditions and the geometric/viscous characteristics of the system, various pairs of gear teeth could be excited, exhibiting a different system response.