Pfeufer, H.
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Lecture
2008
17. EVU Conference, Nice
Pfeufer, H.: Looking inside Crash Data. 17th EVU Conference, Nice 2008
English, 10 pages, 16 figures, 10 references
This paper evaluates 70 experimental rear-end collisions with collision induced speed changes of 8 – 12 km/h. An attempt is made to find a function that describes the progression of the accelerometer recordings. It turns out that the peaks which are always seen in the acceleration have only a small effect on the resulting speed changes and the distances traversed during the collision. In regard to the precision actually needed in accident reconstruction, it suffices to describe the crash pulse by a smooth, levelling function.
The description in terms of straight lines (contact force method) as well as by sinusoidal functions (spring model) leads to an acceptable fit in regard to speed changes and distances traversed during the collision. Even the approximation by a constant average acceleration can lead to acceptable results.
For the analysed collisions, the impact durations fell into the 60 – 180 ms range, with clustering in the interval of 100 – 130 ms. As predicted by physics, the maximum acceleration dropped with increasing impact duration, whereas the intrusion depth grew. No dependency could be found between the impact duration and the separation speed. For non-braked impacts, the latter falls into the range of 3 – 6 km/h. Higher separation speeds (up to 8.5 km/h) can only be observed if the bullet vehicle was braked during impact. If the influence of the tyre forces is subtracted, the separation speed for braked impacts falls into the 0 – 6 km/h range.
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