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Suspension system optimisation to reduce whole body vibration exposure on an articulated dump truckKirstein, Johannes Cornelis 12 1900 (has links)
Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2005. / In this document the reduced order simulation and optimisation of the passive suspension
systems of a locally produced forty ton articulated dump truck is discussed. The
linearization of the suspension parameters were validated using two and three dimensional
MATLAB models. A 24 degree-of-freedom, three dimensional ADAMS/VIEW model
with linear parameters was developed and compared to measured data as well as with
simulation results from a more complex 50 degree-of-freedom non-linear ADAMS/CAR
model. The ADAMS/VIEW model correlated in some aspects better with the experimental
data than an existing higher order ADAMS/CAR model and was used in the suspension
system optimisation study. The road profile over which the vehicle was to prove its
comfort was generated, from a spatial PSD (Power Spectral Density), to be representative
of a typical haul road. The weighted RMS (Root Mean Squared) and VDV (Vibration Dose
Value) values are used in the objective function for the optimisation study. The
optimisation was performed by four different algorithms and an improvement of 30% in
ride comfort for the worst axis was achieved on the haul road. The improvement was
realised by softening the struts and tires and hardening the cab mounts. The results were
verified by simulating the optimised truck on different road surfaces and comparing the
relative improvements with the original truck’s performance.
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Investigation into road rumble in a light utility vehicleWade, Andrew David 03 1900 (has links)
Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2005. / Vehicle Noise, Vibration and Harshness (NVH) is now a more important
component of the vehicle design process than ever. Road noise is one of the
key criteria used by potential buyers (albeit subconsciously) to choose what
they perceive as the best vehicle.
Road rumble is a key concern for vehicle manufacturers. Light Utility
Vehicles (LUVs) are especially sensitive to a low frequency booming noise
due to the fundamental acoustic mode that exists in the vehicle cabin. An
investigation into this booming noise in an LUV is documented. The noise
is identified and quantified after which the source of the noise in the vehicle
cabin is identified using NVH techniques such as Acoustic Modal Analysis
(AMA), Experimental Modal Analysis (EMA) and Transfer Path Analysis
(TPA). The cabin’s fundamental acoustic mode lay at 100 Hz. Finally the
source of the vibrations in the vehicle leading to the booming noise in the
cabin is identified, along with its transfer path to the cabin.
Solutions for the specific vehicle’s booming noise are proposed, two of
which are tested with some success. Solutions to the problems associated
with the fundamental acoustic mode of LUVs are also proposed and discussed.
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