Low Speed Rear End Impact

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PCV (Volvo B10B)


The timescale of the accelerometer was adjusted so that the impact started at 0 seconds. The acceleration reached a peak of 0.3g at 0.32 seconds. The speed change displayed oscillations as the vehicle’s separated.

The wheels of the PCV were stationary and remained so throughout the collision phase.
The sprung mass was accelerated to 0.43mph.

The un-sprung mass did not move as the acceleration applied was insufficient to overcome the frictional force between the tyres and road surface.

Y Axis – Peak vertical accelerations of 0.29g and 0.47g were observed simultaneously at 0.15 second. This suggests an instantaneous compression disparity of 0.18g.

A trough of –0.28g of the head occurred at 0.36 second, where the chest acceleration is –0.09g; a disparity of 0.19g.

A trough of –0.48g of the chest occurred at 0.44 second. The head acceleration was –0.14g demonstrating a disparity of 0.34g.

The time delay of 0.08 second may suggest an elongation of the neck structure.

Z Axis – The first head acceleration peak was found at 0.62g; the chest acceleration at that point being 0.1g. This occurred at 0.1 second and demonstrates a disparity of 0.52g.

At 0.14 second the peak head acceleration was –0.5g with the chest at –0.03g. The disparity is 0.47g.

By 0.52 second, the peak chest acceleration was –0.39g with the head at –0.21g. This is a disparity in favour of the chest of 0.18g.

Citroen ZX


The timescale of the accelerometer was adjusted so that the collision started at 0 seconds. The start of the collision was defined to be when the acceleration became negative and stayed negative. Peak deceleration of 2.4g occurred at 0.19 seconds. The initial deceleration phase took 0.4 seconds, rebound then occurred.

From integration of the acceleration pulse, it was calculated that the impact speed was 8.0 ± 0.1 mph, and that the delta v (∆v) was 9.7 ± 0.1 mph.

The occupant acceleration is expressed in two components; “Y” which denotes the vertical axis, and “Z” which denotes the longitudinal.

Y Axis – Peak vertical (Y) chest and head acceleration of 3.68g and 5.91g occurred at 0.2 and 0.26 second respectively.

At 0.26 second, the chest acceleration was 1.21g allowing for a maximum disparity of 4.7g.

Z Axis – A peak g of 1.9g occurred at the chest at 0.15 second. At this point, a head acceleration of 0.7g was experienced. (Peak 0.8g occurring at 0.17 second.). This first maximum disparity of 1.2g occurred.

A peak head acceleration of –3.06g occurred at 0.24 second. At this point the chest acceleration was 0.3g. The disparity was 3.36g.

A peak forward chest acceleration of 3.2g occurred at 0.27 second. The chest acceleration was 0.6g.

At 0.41 second, the head acceleration was –1.4g the chest being 0.2g. The disparity was 1.6g.

A second forward peak acceleration of 2.9g occurred at 0.57 second. The chest acceleration was –0.4g. The disparity was 3.3g.

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