Design Evaluations On IRS Axle System NVH Through Analytical Studies

Axle whine is an important driveline NVH issue that originates in the hypoid gear sets due to transmitted error excitations. Improving gear quality to reduce the transmitted error has a cost penalty, as well as practical manufacturing limitations. On the other hand, axle system dynamics play a significant role in the system response to gear excitations and in transmissibility from gears to the structure. Analytical tools can be used to tune axle system dynamics in order to alleviate noise and vibration issues. Analytical results can be utilized to evaluate design alternatives, reduce the number of prototypes, thus to reduce product development time. However, analytical results need to be verified and correlated with test results.

In this paper, dynamic behavior of a driveline system is investigated. The finite element model is validated at both component and system levels using frequency response functions and mode shapes. The correlated model is utilized in frequency response analysis to investigate the axle whine issue in the range of 300 to 600 Hz. Modal participation results are used to select participating modes. Strain and kinetic energy results are used to select the component and component design parameters for design iterations. Several design parameters are evaluated to determine their potential to alleviate vibration issues, such as pinion bearing stiffness, halfshaft diameter and the incorporation of a tuned torsional damper.