A Physical Model for Driveshaft Vibration Transmissibility

The driveshafts can be an important contributor to vehicle interior noise including low-frequency (booming) noise where the vibrations, originating in the powerplant, travel to the vehicle body through the driveshafts. A suitable Key Performance Indicator (KPI) for the driveshaft performance is the transmissibility, which is an output/input acceleration ratio and can be used to describe the amount of vibration transferred from the inboard to the outboard joint of the driveshaft. This paper introduces a simple physical model of the driveshaft transmissibility able to support the development and evaluation of the driveshaft and to estimate the effectiveness of countermeasures such as a dynamic damper. The model is validated through comparison with on-vehicle measurements. The proposed approach offers ease of use, low computational cost and clear relation of the measured transmissibility with the system’s physical properties. Good accuracy can be obtained for the booming noise range, especially if the driveshaft attachments are suitably represented through an equivalent stiffness that can be easily obtained from test or computer-aided engineering (CAE). The simplifications in the proposed model may limit the practical range of applicability. Nonetheless, for the low frequency problems considered, it can support the component and countermeasure development, reducing the need for prototype evaluations.