A Brief Investigation into the Effect on Suspension Motions of High Unsprung Mass

7-1-3.jpg
7-1-3.jpg

A Brief Investigation into the Effect on Suspension Motions of High Unsprung Mass

9.95

Author(s): David J. Purdy; Dave Simner
No pages: 6
Year: 2004
Article ID: 7-1-3
Keywords: mobility, tracked vehicles, transmission
Format: Electronic (PDF)
 

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Abstract: Many military vehicles are being developed which use a hybrid electric drive system. Of these, a number utilise drive motors mounted within some or all of the road wheels. Of necessity these wheel-motor assemblies are somewhat heavier than the similar, existing, conventional road wheels. This extra mass has implications for both the ride within the vehicle and the design of the suspension-wheel-motor system. This paper looks at the implications of the extra mass within the wheel assembly as it increases the unsprung mass of the vehicle. Linear and non-linear single-wheel station models have been developed in order to quantify the effects of the modified design. A range of sprung-to-unsprung mass ratios have been analysed using the models. The behaviour of the vehicle at a range of speeds and different obstacles has been simulated. The results show the predicted accelerations and vibration dose value (VDV) vary with both speed and sprung-to-unsprung mass ratio. The behaviour of the suspensions for the random ride and step impact conditions show that the ride quality and acceleration levels deteriorate with vehicle speed. For the pothole simulation, however, the higher unsprung mass conditions show an improvement in some aspects as speeds increase, because the wheel effectively 'skips over' the pothole and the resultant impact is reduced.