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Abstract
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OBJECTIVE Run-off road events occur frequently and can result in severe consequences. Several potential injury causing mechanisms can be observed in the diverse types of run-off road events. Real world data shows that different types of environments, such as rough terrain, ditch types and whether multiple events occur, may be important contributing factors to the occupant injury. While countermeasures addressing front seat occupants have been presented, studies on rear seat occupant retention in situations such as run-off road events are lacking. The aim of this study was to investigate the seatbelt pre-pretensioner effect on rear-seated child sized Anthropomorphic Test Devices (ATDs) during two different types of run-off road events.
METHODS The study was carried out using two test setups; a rig test with a vehicle rear seat mounted on a multi-axial robot simulating a road departure event into a side-ditch, and an in-vehicle test setup with a Volvo XC60 entering a side-ditch with a grass slope, driving inside the ditch, and returning back to the road from the ditch. Potential sub-sequent rollovers or impacts were not included in the test setups. In total, three different ATDs were used. The Q6 and Q10 were seated on an integrated booster cushion and the HIII 5(th) female was positioned directly on the seat. The seatbelt retractor was equipped with a pre-pretensioner (electrical reversible retractor) with three force level settings. In addition, reference tests with the pre-pretensioner inactivated were run. Kinematics and the shoulder belt position were analyzed.
RESULTS In rig tests, the left seated ATD was exposed to rapid inboard lateral loads relative to the vehicle. The displacement for each ATD was reduced when the pre-pretensioner was activated compared to tests when it was inactivated. Maximum inboard displacement occurred earlier in the event, for all ATDs, when the pre-pretensioner was activated. Shoulder belt slip-off occurred for the Q6 and Q10 in tests where the pre-pretensioner was inactivated. During in-vehicle tests, the left seated ATD was exposed to an inboard movement when entering the road again after driving in the ditch. The maximum inboard head displacement was reduced in tests where the pre-pretensioner was activated compared to tests in which it was inactivated.
CONCLUSIONS During both test setups, the activation of the pre-pretensioner resulted in reduced lateral excursion of the Q6, Q10 and HIII 5(th) female due to the shoulder belt remaining on the shoulder and supporting the side of the lower torso. The results provide new insights into the potential benefits of using a pre-pretensioner to reduce kinematic responses during complex run-off road events through supporting the seatbelt to remain on the shoulder. This study addresses potential countermeasures to improve real world protection of rear-seated children, and it provides a broader perspective including the influence of pre-crash kinematics.
Language: en |