Effect of a dual-mass flywheel on the impact-induced noise in vehicular powertrain systems

The appearance and persistence of impact-induced clonk noise in rear wheel drive light truck drivelines has led to an urgent need for remedial action. The pressure for delivering results within tight schedules and financial constraints has resulted in palliative actions rather than fundamental investigations. It has been speculated that the use of a dual-mass flywheel (DMF) can lead to attenuation of clonk metallic noise, even though its main purpose has been to counter transmission rattle by reducing the input torsional impulse. The present work investigates the effect of DMF on impact-induced clonk noise and its severity through experimentation. Sound measurements in the driveline only reveal a slight reduction in the overall levels of impact-induced noise, but a significant change in its quality - the sharpness associated with the typical metallic content of clonk is absent. The effect is also highlighted by the main frequency content of the response when DMF is employed. The duration of the clonk phenomenon is altered from the case where a traditional single solid-mass flywheel is employed.