David Fothergill, SVT & Bentley Motors
This paper describes the use of a system model to create filters with which to modify test measurements for playback in a physical vehicle Noise, Vibration and Harshness (NVH) simulator, and so to provide directional guidance in the design of a luxury passenger vehicle.
The technical approach is described, whereby a whole vehicle model is developed, using the HyperWorks suite, specifically to characterise steady speed and light impact ride responses, and then used to predict the effect of design changes. The updated model results are then manipulated with the baseline results to produce “change filters” in the frequency domain. These filters modify, rather than replace, the results. This obviates the need for explicitly representative road surface simulation, since it is mathematically removed in the process of the (unit-less) filter creation.
A physical simulation process is outlined whereby detailed operating measurements were taken on a test vehicle, under specific driving conditions, and accurately reproduced in a driving simulator. This enabled NVH assessments to be completed in a fully immersive environment.
Thus, jurors were able to subjectively assess the effects of simulated changes to the chassis design based on a combination of test and mathematical modelling.