Preliminary study of uniform restraint concept for protection of rear-seat occupant under mid and high crash severities 2016-01-1528

As the restraint technologies for front-seat occupant protection advance, such as seatbelt pre-tensioner, seatbelt load limiter and airbag, relative effectiveness of rear-seat occupant protection decreases, especially for the elderly. Some occupant protection systems for front-seat have been proved to be effective for rear-seat occupant protection as well, but they also have some drawbacks. Seatbelt could generate unwanted local penetrations to the chest and abdomen. And for rear-seat occupants, it might be difficult to install airbag and set deployment time. For crash protection, it is desirable that the restraint loads are spread to the sturdy parts of human body such as head, shoulders, rib cage, pelvis and femurs, as uniformly as possible. This paper explores a uniform restraint concept aiming at providing protection in wide range of impact severity for rear-seat occupants. In this study, we use THUMS 50th percentile occupant model to simulate response under sled test frontal impact loading. The occupant is restrained by uniform restraint forces respectively acting on head, upper torso and shoulders, and lower extremities in a spread way, through three “plates” respectively positioned against head, upper torso and shoulders, and knees. The force levels are control parameters, which are manually optimized for adapting to crash severity, for maintaining reasonable occupant posture and body kinematics, and resulting in acceptable injuries. Rib fractures, chest deflection, chest acceleration and head acceleration are monitored in simulations. The results show that the restraint forces distributed on the sturdy parts of human body in such a spread way could be more efficient than seatbelt, and can provide rear-seat occupants protection in a wider range of impact velocity with adaptable level of restraint force.