The effect of a moderately reclined seat-back angle on the kinematics of the Large-Omnidirectional Child Anthropomorphic Test Device with and without a belt-positioning booster in frontal crashes.

OBJECTIVE

The effect of reclined seatbacks during frontal crashes in children seated on a belt-positioning booster (BPB) is not understood. Therefore, the aim of this study is to examine submarining in reclined child occupants with and without a BPB and with and without a simulated pre-pretensioner (PPT). We used the Large Omnidirectional Child (LODC) Anthropomorphic Test Device (ATD) seated on a production vehicle seat with and without a moderately reclined seatback angle during sled-simulated frontal vehicle crashes.

METHODS

Ten sled-simulated frontal impact tests were performed (24 g peak, 80 ms duration, 56 km/h delta-V). An adjustable D-ring anchor simulated a seat integrated belt. A fixed load-limited 3-point seatbelt webbing system was used to secure the LODC to a vehicle seat and booster seat. We compared the following conditions: a) BPB vs no-BPB and b) 25° versus 45° seatback angles, c) PPT, vs no-PPT in 45° seatback condition, each test was repeated. Abdominal forces (left and right), seatbelt loads, Anterior-Superior-Illiac-Spine forces (ASIS, upper and lower, left and right), and pelvis rotation were analyzed.

RESULTS

Average peak abdominal pressures were smaller in both nominal and moderate recline positions in the BPB (25°: 73.7 kPa, 45°: 82.5 kPa) compared to the no-BPB conditions (25°: 168.4 kPa, 45°: 339.1 kPa). In the 45° recline no-BPB conditions, both the peaks of the lap belt force and ASIS forces occurred early and a rapid reduction in those forces followed. This change in the lap belt and ASIS forces accompanied a rearward rotation of the pelvis. During the reduction of ASIS and lap belt forces, there was an increase in abdominal pressure suggesting that the lap belt moved upward, off the ASIS, and into the abdominal pressure sensor. There was a slight reduction in head and knee excursion with the PPT. These results suggest the presence of submarining in the 45° recline no-BPB conditions but not in the 45° recline with the BPB.

CONCLUSIONS

The BPB could be beneficial when the seatback is moderately reclined. The differences during the moderate recline between the BPB and no-BPB conditions also indicate that the BPB could prevent submarining in moderately reclined seats.