Parameter study for child injury mitigation in near side impacts through FE simulations

Artikel i vetenskaplig tidskrift, 2012

Objective: The objective of this study is to investigate the effects by crash related car parameters on head and chest injury measures for 3- and 12-year-old children in near side impacts. Methods: The evaluation was made by using a model of a complete passenger car which was impacted laterally by a barrier. The car model was validated in two crash conditions: the IIHS and the USNCAP side impact tests. The SID-IIs and the HBM3 (THUMS 3-yo) finite element models were used for the parametric investigation (HBM3 on a booster). The car parameters were: vehicle mass, side impact structure stiffness, a head airbag, a thorax-pelvis airbag, and a seat belt with pretensioner. The studied dependent variables were: resultant head linear acceleration, resultant head rotational acceleration, chest viscous criterion, rib deflection, and relative velocity at head impact. The chest measurements were only considered for the SID-IIs. Results: The head airbag had the greatest effect on the head measurements for both of the occupant models. On average, it reduced the peak head linear acceleration by 54 g for the HBM3 and 78 g for the SID-IIs. The seat belt had the second greatest effect on the head measurements; the peak head linear accelerations were reduced on average by 39 g (HBM3) and 44 g (SID-IIs). The high stiffness side structure increased the SID-IIs head acceleration, while it had marginal effect on the HBM3. The vehicle mass had marginal effect on SID-IIs head accelerations, while the lower vehicle mass caused 18 g higher head acceleration for HBM3 and the greatest rotational acceleration. The thorax-pelvis airbag, the vehicle mass and the seat belt pretensioner affected the chest measurements the most. The presence of a thorax-pelvis airbag, high vehicle mass and a seat belt pretensioner all reduced the chest VC and peak rib deflection in the SID-IIs. Conclusions: The head and thorax-pelvis airbags have the potential to reduce injury measurements for both the SID-IIs and the HBM3, provided that the airbag properties are designed to consider these occupant sizes also. The seat belt pretensioner is also effective, provided that the lateral translation of the torso is managed by other features. The importance of lateral movement management is greater the smaller the occupant is. Light vehicles require interior restraint systems of higher performance than heavy vehicles do to achieve the same level of injury measures for a given side structure.