Ting Noise Generation in Automotive Applications

Automobile customers are looking for higher performance and quieter comfortable rides. The driveline of a vehicle can be a substantial source of NVH issues. This paper provides an understanding of a driveline noise issue which can affect any variant of driveline architecture (FWD, AWD, RWD and 4X4). This metallic noise is mostly present during the take-off and appropriately termed as ting noise. This noise was not prevalent in the past. For higher fuel economy, OEMs started integrating several components for lighter subsystems. This in effect made the system more sensitive to the excitation. At present the issue is addressed by adding a ting washer in the interface of the wheel hub bearings and the halfshafts.

This paper explains the physics behind the excitation and defines the parameters that influence the excitation. The halfshaft and the wheel hub are assembled with a specified hub nut torque. Based on powertrain torque input to the wheel and road resistance, the halfshaft interface area may slide relative to the wheel hub bearing. The coefficient of friction between the two interfacing surfaces changes from static friction to kinetic (sliding) friction. This change in coefficient of friction causes the clamping force to change thus giving rise to the axial excitation force.