Comparative performance of forward-facing child restraint systems on the C/FMVSS 213 bench and vehicle seats.

OBJECTIVE

The objective of this study was to evaluate the fidelity of the C/FMVSS 213 test bench, by comparing the dynamic performance of forward-facing child restraint systems (FFCRS) mounted on the C/FMVSS 213 sled bench versus mounted on a selection of production vehicle seats.

METHODS

The C/FMVSS 213 bench or one of 3 second-row original equipment manufacturer vehicle seats was mounted to the deck of acceleration crash sled. An FFCRS with a restrained anthropomorphic test device (ATD) was secured by 3-point belt (3-PT) or LATCH lower anchor (LLA) on the C/FMVSS 213 bench or vehicle seat, with or without a tether. The sled was then exposed to a 48 km/h acceleration pulse. Three unique make and model vehicle seats and FFCRS were tested. Fifty-three sled tests were performed.

RESULTS

When FFCRS were secured with LLA and no tether, little difference between the vehicle seats and 213 bench was observed. Similarly, when FFCRS were affixed with 3-PT and no tether, few kinematic variable differences achieved statistical significance; chest resultant acceleration was, on average, 9.1 g (SD=6.6, P=.006) higher on the vehicle seats compared to the bench, as was CRS seatback excursion (difference [Δ] of 39.8 mm, SD=32.7, P=.011) and ATD knee excursion (Δ=36.4 mm, SD=12.0, P<.001). However, when the tether was added to either the 3-PT or LLA attachment methods, the difference between the bench and vehicle seats was more pronounced. ATD kinematic measures such as head resultant acceleration (Δ=14.6 g, SD=7.2, P<.001) and pelvis resultant acceleration (Δ=8.6 g, SD=6.0, P=.005) were higher on the vehicle seats compared to the bench, as were the injury metrics for head and chest injury: ΔHIC15=162.2 (SD=87.4, P=.001) and ΔChest 3 ms clip=5.5 g (SD=6.2, P=.040). Of note, CRS (Δ=62.8 mm, SD=32.7, P=.000) and ATD head (Δ=66.3 mm, SD=30.9, P=.000) and knee (Δ=46.9 mm, SD=25.8, P=.001) forward excursion were all higher on the vehicle seats compared to the bench in 3-PT with tether condition.

CONCLUSIONS

Without the tether attached, we observed few kinematic and kinetic differences between the vehicle seat and the C/FMVSS 213 bench, suggesting that the bench is an adequate surrogate for the vehicle seat in this condition. With the tether attached, we found significant differences between the C/FMVSS 213 bench and vehicle seats, suggesting that the fidelity of the bench could be improved in the tethered mode. When differences were statistically significant, excursion and injury metrics were generally greater on the vehicle seats than on the C/FMVSS 213 bench.