The aims of this study were to investigate the kinematics of child
anthropomorphic test devices in a large sample of rear-facing child restraint
system installations and the effects of anti-rebound features and load legs on
the kinematics of rear-facing child anthropomorphic test devices.
The test matrix included a general sample of 70 rear-facing child restraint
system installations to observe trends in frontal crash tests; 14 full-scale
crash tests with paired comparisons to investigate the effect of anti-rebound
features; and five paired comparisons of rear-facing child restraint systems
installed with and without a load leg. The paired t-test was used to determine
the statistical significance of differences in kinematic responses.
In the general sample, 84% of anthropomorphic test devices in infant seats with
the base in outboard seats interacted with the first-row seat. In 52% of tests,
the anthropomorphic test device head directly contacted the front seatback. Head
accelerations > 80 g were caused by interactions between: the child restraint
system and front seatback; the anthropomorphic test device head and the interior
surface of the child restraint system; or the anthropomorphic test device head
and front seatback.
In the anti-rebound sample, head contact on rebound occurred in three infant seat
installations, and all were associated with head resultant accelerations ≤33 g.
The mean paired difference in head 3 ms clip was negligible (p > 0.05).
In the load leg sample, the load leg limited forward excursion and forward
rotation of the rear-facing child restraint system, thereby contributing to the
containment of the anthropomorphic test device within the boundary of the child
restraint system shell.
In this study, anti-rebound features did not improve the kinematics of pediatric
anthropomorphic test devices. The feasibility of including the use of the load
leg in the Canadian regulatory test protocol should be explored.
