Abstract: It is well known that airbag restraint system is a kind of effective and important passive safety equipment; it can reduce the impact force of the second collision during a crash. However, airbag not only provides protection but also may cause injuries to the occupants especially to the out-of-position occupants. So it is quite necessary to proceed with further researches on its related techniques to minimize the possible side-effects. A further research on the sandwiched tube-type airbag invented by the author is made. The sled tests and virtual testing technique are used together, first the collision accelerations are collected from sled tests and treated as baseline. The baseline curves are synthesized with the white noise generated by the computer to form the collision curves for the virtual tests. By using the finite element modeling technology and MADYMO virtual testing technique, the static initiation characteristics and protection effect of the sandwiched tube-type airbag are analyzed, and the simulation results indicate that the tube-type airbag deploys steadily and the deploying mode is well controllable, so it can reduce the injury risk and provide better protections to the out-of-position occupants. The structural optimization is performed to work out the potential instability problem.

Key words: Structural optimization, Finite element method simulation, Out-of-position occupant, Protection effect, Sandwiched tube-type airbag