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Paper Title:
Theoretical Study of
Motor Vehicle Pole Impact
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Authors:
Raphael Grzebieta, Robert
Milner, Roger Zou
Abstract:
'Single vehicle crashes',
where occupants are killed or seriously injured as a result of vehicles
leaving the roadway, constitute a substantial proportion of the
road crash problem. Around 35% of these crashes involve poles or
trees. If a 20% reduction in the road toll is to be realised by
2010 then a strategy dealing with such crashes needs to be introduced.
This paper proposes a passive crashworthiness measure, where a timber
light pole can be weakened such that it fractures in a manner similar
to a frangible pole system, at impact speeds greater than 40 km/hr.
A theoretical model,
even one greatly simplified, that identifies the significant parameters
and can be used for routine pole design is a useful tool. The model
proposed in this paper, compares its predictions with those of a
commercial dynamic analysis package and presents the results of
a parameter study that identifies the important pole parameters
and quantifies their effect. The parameter study highlights the
fact that the act of simply making a pole frangible will not, of
its own, reduce vehicle decelerations to levels where car occupants
are likely to survive. Pole mass also plays a significant role.
The paper is specifically concerned with:
-Identification of the parameters that affect motor vehicle deceleration
rates during a pole impact and quantification of their effect.
-Development of a closed form solution, based on simplifying assumptions,
that adequately describes the impact event and enables the designers
of frangible poles to predict the peak deceleration rates without
having to resort to expensive commercial computer packages. The
simplified model has also proven useful in describing the sequence
of events that are sometimes masked by numerical solutions.
-Comparison of the prediction of the closed form solution with that
provided by the general purpose dynamic engineering program, MADYMO.
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