Rear-Facing Infant Seat Structural Integrity and Crashworthiness Under Front Seatback Loading in Rear-Impact Collisions

Rear-facing infant seats positioned behind front outboard vehicle seats are vulnerable to loading from rearward-yielding front seatbacks during rear-impact collisions in the presence of front occupants. This seatback loading can collapse and deform the infant seat’s plastic shell, increasing the risk of head injuries to the infant occupant. Shell deformation also introduces slack into the five-point harness system, exacerbating head excursions beyond the protective boundaries of the shell and increasing the likelihood of head contact with components such as the carry handle. Current rear-facing infant seat designs typically do not account for loading imposed by the front seatback during rear-impact scenarios, resulting in weak and collapsible shell structures. Furthermore, regulatory compliance tests, such as FMVSS 213, lack provisions for evaluating rear-facing infant seats under realistic rear-impact conditions. The standard test bench does not incorporate simulated vehicle interiors or front seatbacks, failing to replicate critical loading mechanisms observed in real-world crashes. This study highlights the need for revised testing methodologies employing sled testing with realistic seatback intrusion conditions to support the development of improved infant seat designs. Sled testing demonstrated that convertible seats, by virtue of their stronger, intrusion-resistant shell designs, mitigated shell collapse and maintained occupant protection, thereby reducing the risk of head injuries during rear impacts even in presence of yielding front seatback. The results suggest that rear-facing infant seats, when designed to account for realistic loading conditions, can adhere to established crashworthiness principles and produce favorable injury outcomes for infants in rear-impact scenarios.