Prediction of mobility, handling, and tractive efficiency of wheeled off-road vehicles
Our society is heavily and intrinsically dependent on energy transformation and usage. In a world scenario where resources are being depleted while their demand is increasing, it is crucial to optimize every process. During the last decade the concept of energy efficiency has become a leitmotif in s...
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Virginia Tech
2014
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| Online Access: | http://hdl.handle.net/10919/37781 http://scholar.lib.vt.edu/theses/available/etd-05112010-000153/ |
| Summary: | Our society is heavily and intrinsically dependent on energy transformation and usage.
In a world scenario where resources are being depleted while their demand is increasing, it
is crucial to optimize every process. During the last decade the concept of energy efficiency
has become a leitmotif in several fields and has directly influenced our everyday life: from
light bulbs to airplane turbines, there has been a general shift from pure performance to
better efficiency.
In this vein, we focus on the mobility and tractive efficiency of off-road vehicles. These
vehicles are adopted in military, agriculture, construction, exploration, recreation, and mining
applications and are intended to operate on soft, deformable terrain.
The performance of off-road vehicles is deeply influenced by the tire-soil interaction
mechanism. Soft soil can drastically reduce the traction performance of tires up to the
point of making motion impossible. In this study, a tire model able to predict the performance
of rigid wheels and flexible tires is developed. The model follows a semi-empirical
approach for steady-state conditions and predicts basic features, such as the drawbar pull,
the driving torque and the lateral force, as well as complex behaviors, such as the slip-sinkage
phenomenon and the multi-pass effect. The tractive efficiency of different tire-soil configurations is simulated and discussed. To investigate the handling and the traction efficiency,
the tire model is implemented into a four-wheel vehicle model. Several tire geometries, vehicle
configurations (FWD, RWD, AWD), soil types, and terrain profiles are considered to
evaluate the performance under different simulation scenarios. The simulation environment
represents an effective tool to realistically analyze the impact of tire parameters (size, inflation
pressure) and torque distribution on the energy efficiency. It is verified that larger
tires and decreased inflation pressure generally provide better traction and energy efficiency
(under steady-state working conditions). The torque distribution strategy between the axles
deeply affects the traction and the efficiency: the two variables canâ t clearly be maximized
at the same time and a trade-off has to be found. === Ph. D. |
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