Optimization study of occupant restraint system concerning variations in occupant size and crash severity

Yi Huang, Qing Zhou, Xiaowei Zhang and Cong Wang (Massachusetts Institute of Technology)

CHALLENGE - The current legislative or consumer crash tests, that encourage restraint system configurations, cannot provide tailored protection to occupants with different statures under various crash severities. The restraint system parameters should be adapted to different circumstances. In this study, a restraint system optimization framework was built to explore optimal configurations for 5 different sizes of occupants in 2 crash severities. 

SOLUTION - In order to give a comprehensive evaluation to the performance of the occupant restraint system, a Weighted Injury Criteria (WIC) was used. WIC assigns different weights to the injury values according to the probability of the injury distribution from the traffic accident statistics. A sled model representing the front seat passenger side restraint system of a large family car was developed in MADYMO. On the basis of the restraint system model, several parameters, including airbag stiffness, seatbelt behavior, and seat position, were set as variables, in order to change restraint system characteristics. In order to facilitate optimization of restraint system for 2 crash severities with 5 dummy models in a relatively large design space, an automated optimization framework was built with the help of optimization software modeFRONTIER and Perl scripts. With the consideration of high nonlinearity of restraint system, a heuristic optimization method MOGA-II was employed.








BENEFITS - In the 56 km/h crash test, the WIC of each case was greatly reduced. Among the 6 body-region normalized injury readings, head injury had the largest decrease. Chest compressions in small size dummies were reduced by more than 20%.