Abstract:

A method to optimize the parameters of seatbelt constraint paths was built using a design of
experiments (DOE) method to improve the safety performance of a type of seat belt fixed of the child restraint
systems (CRS). A front crash simulation model was set-up using an FE model of CRS and a Hybrid III 3-year
old child dummy. The simulation results were verified with some sled tests. The influences of the seatbelt guide
ring positions, the seat skeleton thickness and the friction coefficient between child and five-point harness on
injury parameters, such as head injury criterion (HIC15) values, chest resultant acceleration and chest vertical
acceleration, were analyzed after improving CRS framework structure, and by using orthogonal experimental
design to select parameters. The results show that the head maximum displacement reduces from 1.5% higher
than the regulation threshold to 15% lower than the threshold. The seatbelt guide ring position is the most
sensitive factor. Therefore, optimizing the seatbelt guide ring position and reducing the friction coefficient can reduce the maximum displacement of the head.

Key words: auto safety, child occupant injury, child restraint system (CRS), seat belt, orthogonal experimental design, finite element analysis