The Crash Pulse in Rear-End Car Accidents The Influence of: Under-ride, Over-ride, Offset and a Tow-bar

The aim of this study is to see what the influence of tow-bars is in rear-end collisions, hereby looking at the crash pulse. The database from the Swedish insurance company Folksam and some full-scale tests performed by Autoliv [I, 241 give an indication that the tow-bar increases the injury risk. The increased average acceleration correlates to the increased injury risk. First of all a literature survey is done to see what is already known about rear-end crashes. The survey show that there is a twice a higher risk for whiplash injuries in rear-end collisions t h ~ ~ front21 czes, but there ~5 front$ c~l! is io~s t h z ~ rezr-end cnllisior;. Therefore there are mme pe~p l e with whiplash in3zries from frontal collisions. For further investigation of rear-end collisions it is good to know what the distribution of this type of collision is. This distribution was found in the Whiplash 11 report [8]. Apparently 56% of all rear-end crashes are full overlap and 28% of rear-end collisions have 'I3 to 2/3 overlap. It is not interesting to investigate the 0 to 'I3 overlap situation (14,2% of all rear-end collisions) in this study, because it is a small part of all rear-end crashes and the striking car is not going to hit the tow-bar of the struck car in this configuration. In a report from Krafft et a1 6181 and from a report from Autoliv [I] some research has been done to see what the influence of a tow-bar is. The results show that there is an increase of 22% in risk of getting a CSD when a car has a tow-bar. The crash pulse is also different. However, only one full-scale test was done, so no conclusions could be made in other test configurations, which is shown in a report from Meyer et a1 [12]. The latest database from Folksam and full-scale test performed by Autoliv [24] show that 2 other parameters are influencing the crash pulse. They found that an under and over ride situation have also influence on the crash pulse. Now all the relevant data is known, a test set up for simulation is made. Looking at the data gained from the literature survey the next 3 strategies are formulated: 1. Influence of underlover ride on the crash pulse 2. Influence of the amount of overlap on the crash pulse 3. Influence of a tow-bar on the crash pulse at different amounts of overlap and underlover ride For strategy 1 the configuration is altered to create the underlover ride situation and for strategy 3 the tow-bar is modeled and then added to the struck car. The results show that is not good having a rear-end collision with over ride with or without a tow-bar. The under ride configuration will give lower acceleration in the first 75 ms of the crash, thus it is better having under ride. Adding the tow-bar gave a stiffer pulse, but it is still safer to have an under ride situation with a tow-bar than the standard configuration. In the partial overlap configuration can also be concluded there is less risk of getting a WAD than in the standard configuration. A tow-bar on the struck car in offset crashes led to higher accelerations. This proofs that the results of the single test conditions from Autoliv are also applicable to other conditions. The Influence of: Under-ride, Over-ride, Offset and a Tow-bar 2