A study and comparison of the effects of low speed change vehicle collisions on the human body
Highlights
► We performed three low speed, vehicle-to-vehicle crash tests of incrementing magnitude. ► We measured the effects on the occupants in terms of acceleration and compared the results to previous research. ► We measured the effects of an everyday activity in terms of acceleration and compared the results of low speed crash tests with the everyday activity. ► We observed an increase in vehicle damage with increased target vehicle speed change, with respect to structure. ► We found a strong positive correlation between target vehicle speed change and occupant movement.
Introduction
There is a well-established link between the damage sustained by a vehicle in a rear-end collision and the speed change that vehicle experienced (Tumbas and Smith, 1988, Cheng and Guenther, 1989, Robinette et al., 1994, Kornhauser, 1996, Schmidt et al., 1998, Anderson et al., 2007). That change in speed is often referred to as delta-V, which is the change in velocity over the time period of the collision. A positive relationship between delta-V and the likelihood of occupant injury is also well documented (Cheng and Guenther, 1989, McConnell et al., 1993, Szabo et al., 1994, Robinette et al., 1994, Bailey et al., 1995, Fay et al., 1996, Zuby, 2004). Previous international research as well as previous studies by the authors suggest delta-V thresholds for injury (McConnell et al., 1993, Szabo et al., 1994, Bailey et al., 1995, Henderson, 2006). The previous findings by the authors (Henderson, 2006) proposed a new threshold focussed on the relative motion of the head and the chest.
Previous studies acknowledge that human volunteer subjects are preferable to dummies or cadavers and recognise a lack of data from human volunteers. The aim of this research is to increase the existing dataset with human volunteers and investigate the occupant movement created by a low speed change collision in comparison with an everyday event. With increased real world data the newly proposed threshold is put to the test.
In order to increase the existing dataset, three full-scale, rear impact crash tests were performed. The delta-V for each test was measured as was the level of occupant movement in the target vehicle. The main limitation of full-scale crash testing is that the costs involved constrain the sample size and limit the opportunity for repeatability. The motion of the subject was analysed by measuring the acceleration of the head and of the chest. A hypothesis was tested that there is a correlation between delta-V and head/chest accelerations. The results from the full scale testing were compared with previous research in order to investigate the possibility of a threshold at which collision accelerations are similar to those experienced in everyday events. Sitting into a chair was proposed as a suitable every day event for comparison purposes.
This paper will provide a summary of existing research into occupant movement in low speed rear impacts before describing the methodology behind the full-scale crash testing and comparisons. A results and analysis section compares the new data from full scale crash testing. The new findings are then discussed and summarised.
Section snippets
Literature review
Vehicle crush deformation and energy equivalence relationships are widely accepted as technical accident reconstruction tools for estimating the change in velocity (“delta-V”) during an impact (Robinette et al., 1994). Delta-V has been accepted as a basis for evaluating damage severity and potential for injury severity (Robinette et al., 1994). From that it follows that there is a relationship between the potential for injury and vehicle delta-V.
In 1993 McConnell et al. recognised a lack of
Aims
Three full-scale crash tests were performed using live occupants. The reaction of the occupants was monitored using accelerometers attached to the head and the chest.
Vehicles
Two vehicles were used over the three tests. The first, a 2000(X) registered Alfa Romeo 156 T-Spark, 1747 cc petrol engine, manual transmission, four-door saloon had an unladen mass of 1230 kg. The second, a Ford Focus 1.6 L circa 1998–2002, petrol engine, manual transmission, five-door hatchback had an unladen kerbside mass of
Results
Fig. 3 shows the target vehicle acceleration profiles in the forward direction for each of the three collision tests. Accelerations in the x-axis only are considered as it is these that result in the occupant injury (Mansour and Romilly, 2011).
Fig. 4 shows the speed change for the target vehicle in each test. The overall shapes of the traces are representative of those obtained from low speed impacts involving vehicles with typical bumper systems (Welcher et al., 2001).
Table 1 shows the peak
Discussion
The full-scale collision tests are consistent with the previous research (Tumbas and Smith, 1988, Cheng and Guenther, 1989, Robinette et al., 1994, Kornhauser, 1996, Schmidt et al., 1998, Anderson et al., 2007) in that there is a correlation between impact speed and delta-V: the greater the impact speed, the greater the speed change for the target vehicle. The data from the three crash tests are displayed alongside the Henderson test (Henderson, 2006) in Fig. 8. Correlation is strong and a
Conclusions
Three full scale crash tests and three everyday activity tests were performed to analyse and compare the reaction to human volunteer subjects in terms of head and chest accelerations.
There was a strong correlation between bullet vehicle closing speed and target vehicle speed change (delta-V) and a strong positive correlation between target vehicle delta-V and occupant movement which was in line with previous literature.
There was a strong positive correlation between target vehicle delta-V and
Acknowledgement
P. Fidler, GBB (UK) Ltd.
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Putting the 5 mph injury threshold to the test
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