Time-domain Transfer Path Analysis for Transient Phenomena Applied to Tip-in/Tip-out (Shock & Jerk) 2012-01-1545
Tip-in/Tip-out of the accelerator pedal generates transient torque oscillations in the driveline. These oscillations may be amplified by P/T, suspension and body modes and will eventually be sensible at the receiver side in the vehicle, for example at the seat or at the steering-wheel.
The forces that are active during this transient excitation are influenced by non-linear effects in both the suspension and the power train mounts. In order to understand the contribution of each of these forces to the total interior target response (e.g. seat rail vibration) a detailed investigation is performed.
Traditional force identification methods are not suitable for low-frequent, transient phenomena like tip-in/tip-out. Mount stiffness method can not be used because of non-linear effects in the P/T and suspension mounts. Application of matrix inversion method based on trimmed body vibration transfer functions is not possible due to numerical condition problems.
This paper describes how the forces resulting from the Tip-in/Tip-out excitation are identified in the time-domain using a time-domain TPA-model. This force-identification is fully based on experimental data. The operational data includes strain signals and is acquired during on-road operational measurements and transfer functions are acquired in trimmed-body FRF-measurements.
With the identified forces the time-domain contributions to the total target response can be identified and evaluated at each time-step of the transient phenomenon. This differs from the classical frequency domain TPA - in which the path-contributions represent the averaged frequency content over a certain amount of time and not the contributions at a specific time-step.