Seat Structural Design Choices and the Effect on Occupant Injury Potential in Rear End Collisions

The seat is the most important safety device available to vehicle occupants during rear end collisions, and thus proper design and structural integrity of the seat under expected impact loading is essential. The objective of the current research work is to increase our understanding of the design requirements for seat performance in relation to injury producing collisions, and to examine how various seat design parameters affect both structural integrity and occupant protection. A numerical model-based parametric study was developed based upon the 2002 GM Grand Am seat. The parametric study utilizes a 50^th percentile male dummy, applies the FMVSS 202 standard crash pulse to selected structural variations of this seat, and then utilizes the neck injury criterion (NIC) and neck displacement criterion (NDC) to assess the likelihood of injury.

The recliner rotational stiffness and the head restraint stiffness are the most significant seat structural design choices that can mitigate injury potential. Trends indicate that dual recliners offer reduced injury potential over single recliner seat designs. Injury reduction is seen through a compliant thoracic seatback region. Conversely, allowing pelvic translation increases the likelihood of injury through increased seat and occupant differential velocities. The results indicate that the risk of occupant ejection is reduced significantly through the use of seat-mounted seatbelt retractors, although dual retractor systems mounted to the b-pillar and seat base provide comparable ramping reduction.