Most motor vehicle crash deaths occur among children traveling as passenger vehicle occupants, and proper restraint use and direction of use can reduce these fatalities. There is little to no literature on systematic evaluation on the responses of children under three-years of age in motor vehicle crashes. The study presents the first ever endeavor at developing 18MO, 24MO, 30MO, and 36MO pediatric finite element models from the 6YO PIPER human body model as the baseline and comparing their responses in rear-facing and forward-facing simulations of the same crash pulse conditions in the FMVSS No. 213 test bench and a vehicle seat.

The 6YO PIPER model was scaled down to create anthropometrically accurate models of the 18MO, 24MO, 30MO and 36MO child using the PIPER scaling tool and Snyder anthropometric data. Each model (N=4), along with a convertible car seat and either the 213-test bench or a 2012 Toyota Camry vehicle rear seat was simulated in a full- frontal crash (24G, 120ms pulse). Kinetics and kinematics were extracted and processed as per SAEJ211 metrics.

On the 213-test bench, models in forward-facing configuration showed higher head accelerations, but lower pelvis accelerations for 30MO and 36MO models. Chest displacements were between 84-90% higher in the forward-facing models, with the exception of the 30MO model, which was 35% higher. Neck moments were lower in all rear-facing configurations. Upper neck forces were at least six times higher forward-facing. HIC36 in rear-facing models ranged from 300-344, while HIC36 in forward-facing models ranged from 410-494, showing no linear trend as age increased. Forward-facing head excursions grew over two-fold from their rear-facing counterparts, from an average of 240 to an average of 518. Head trajectories generally followed a longer path in forward-facing models. NIJ for all forward-facing models were five to eight times the values for rear-facing. On the vehicle seat, the forward-facing models showed higher head accelerations for 24MO and 36MO models. Chest displacements were 33-49% higher in forward-facing models, except 36MO, where it was 128% higher. Neck forces and moments were consistently lower for rear-facing models as compared to forward-facing. Upper neck forces were 6.5-9.75 times higher in forward- facing models. HIC36 values were lower in rear-facing, ranging from 335-394, as compared to forward-facing which were 455-624. Head excursions for forward-facing were three times that for rear-facing, except the 36MO model, where it was 1.75 times higher. NIJ for all forward-facing models were six to nine times the values of rear- facing.

Kinetics and kinematics numbers across the board were within IARV limits. Pediatric models in rear-facing configurations generally had lower injury numbers than those in frontal configurations. However, there is no consistent trend seen in injury values as age progresses. This is the first study to conduct a systematic evaluation of the response of children under three years old in frontal motor vehicle crashes.