Occupant protection performance in frontal crashes has been developed and assessed for mainly front seat occupants over many years, and in recent years protection of rear seat occupants has also been extensively discussed. Unlike the front seats, the rear seats are often occupied by children seated in rear- facing or forward - facing child restraint systems, or booster seats. In the European New Car Assessment Program (NCAP), child occupant protection assessments using 18-month-old and 3-year-old test dummies in the rear seat are already being conducted. In addition, studies are under way concerning the development and introduction of test dummies of 6-year-old (6YO) and 10.5-year-old children.
In this study, we focused on 6-year-old children sitting in belt-positioning booster seats. Offset frontal crash tests were conducted using two types of test dummies, a Hybrid III 6YO and a 6YO Q-series dummy (Q6), positioned in the rear seat. The Hybrid III 6YO and Q6 were used to compare dummy kinematics in rear seating positions between (a) behind the driver's seat and (b) the front passenger's seat. The full vehicle crash test results of both dummies showed that the chest deflection tended to be lower on the impacted side than on the non-impacted side in the seating position.
Comparison of Hybrid III 6YO and Q6 dummy kinematics on non-impacted side revealed that the difference in shoulder belt interaction were observed due to the dummy structural differences of the shoulder and chest regions.
Based on the results of these investigations, this paper describes those important aspects that should be taken into account when evaluating rear seat occupant protection for 6-year-old children.