Rear seat child safety in near-side impacts: a modeling study of common sitting positions.
OBJECTIVE
The purpose of this study was to evaluate and propose improvements to the injury mitigation systems, in near-side impacts, for 6 common sitting positions of young adolescents using a previously validated model.


METHODS
The evaluation was made by using a model of a complete passenger car, including head and thorax-pelvis air bags, which was impacted laterally by a barrier in 2 load cases. The SID-IIs finite element model was used for the evaluations and was seated in 6 different positions in the rear outboard seat: the nominal anthropomorphic test device (ATD) position, 1 inboard position, 3 outboard positions, and 1 braking (forward) position. These positions have previously been identified as common sitting positions in awake and asleep children. The studied dependent variables were head injury criterion (HIC) 36, resultant head linear acceleration, resultant head rotational acceleration, chest viscous criterion, and chest deflection.


RESULTS
The lowest head injury measures were seen in the braking positions and in the nominal ATD position, and the highest were seen in the inboard and outboard positions. The lowest chest injury measures were recorded in the inboard and nominal ATD positions, and the highest were recorded in the outboard and braking positions. The occupant in the outboard positions interfered with the air bags during their deployment. The occupant in inboard and braking positions tended to push the curtain air bag over the windowsill.


CONCLUSIONS
Studies that investigate the injury mitigation effects in common sitting positions, beyond the nominal ATD position, are essential to highlight means to provide improved and robust safety for child occupants. This study was based on the SID-IIs 5th percentile female, which has very similar anthropometry to a 50th percentile 12-year-old. Therefore, the conclusions of this study are applicable to many 11-year-olds up to young adolescents, as well as to small females. The outboard and inboard positions of this study resulted in the highest head injury measures. Although all of the injury measures were only slightly higher than the nominal position, the trends suggest that, in near-side impacts, these positions should be discouraged. The extensively outboard positions resulted in unfavorable air bag positioning during deployment. The inboard position resulted in head strikes further forward of the nominal one; the curtain air bags need inflated cells at all locations of head strike.
Applied Mechanics, Chalmers University of Technology, Gothenburg, Sweden. marianne.andersson@combitech.se
Marianne
M
Andersson
Bengt
B
Pipkorn
Per
P
Lövsund
D000063:Accidents, Traffic / Q000706:statistics & numerical data*; D000293:Adolescent; D017278:Air Bags; D002648:Child; D057207:Child Restraint Systems; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D008954:Models, Biological; D011187:Posture; D014947:Wounds and Injuries / Q000517:prevention & control*