Contrary to the recent past when frontal crash restraint systems for the American market were specifically configured with the objective to minimize the occupant injury criteria HIC and chest acceleration, this subsequent study shows that, as a result of the New Car Assessment Program (NCAP) changes, the Neck Injury Criterion Nij and chest deflection have become the new focus of restraint system design. In addition, maximum chest acceleration must still not be exceeded, according to legal requirements. With regard to the neck criterion Nij, tests with the HIII 5% dummy have shown that Nij-values, relevant for the rating, can already arise during pretensioning or during the subsequent coupling phase, prior to the load limiting phase. From this it follows that the maximum pretensioning performance may be limited by this criterion for a few vehicle environments on the passenger side. With reference to the deflection it can be shown that lower thorax acceleration does not automatically lead to reduced chest deflection. Much rather, the belt geometry as well as the belt forces are to be optimized for improved chest deflection values.
Keywords:
frontal impacts; safety belts; Hybrid III; neck; thorax