Abstract:  A numerical frontal impact sled model was constructed and simulated consisted of driver side cockpit and elderly
human body for an optimal design of restraint system, i.e., air bag and seat belt. The objective function in the optimization process
was to minimize the chest injury risk while keeping the other injury risks (i.e., head injury criterion (HIC) and femur load) under
the thresholds. There were three design variables for the restraint, i.e., peak force of belt load limiter, deployment time of belt
pretensioner/airbag, and the vent hole size. The results show that the smaller size of vent hole, earlier firing of belt pretensioner/
airbag and lower belt limit load are needed to reduce the chest injury risk of elder driver in a front crash by comparing with the
restraint design for the younger population.

Key words: automotive safety, frontal impact, restraint system, chest injury risk, elder driver