Investigation of risk factors affecting injuries in reclining seat under frontal impact

Abstract

In autonomous vehicles, passengers often recline their seatbacks for a more comfortable posture. Such a reclined posture greatly increases risk of submarining and other injury concerns due to the unfavourable geometrical configuration of occupant, seat and seatbelt. In this paper, numerous simulations with a modified computational dummy model are proposed to analyse effects of various occupant restraint systems in frontal impact, including seatbelt, pretensioner, load limiter, locking tongue, airbag, knee bolster and so on. After the sensitivity analyses, four concepts for designing anti-submarining countermeasures are proposed: (1) increase the lap belt-to-pelvis friction coefficient; (2) reduce the shoulder belt force along with the use of the locking tongue; (3) increase the lap belt angle; (4) reduce the H point forward and downward displacement. Sled tests with anti-submarining countermeasures were conducted to verify the effectiveness of the anti-submarining concepts for reclining seats. Four anti-submarining countermeasures are suggested to prevent the submarining with no other auxiliary hurts: load limiter plus locking tongue, anchor pretensioners plus anti-submarining bar, seat cushion airbag, and retractor plus buckle pretensioner. This paper could give better understanding of submarining mechanism and eligible vehicle design.