Improve Safety Balance between Women and Men in Frontal Crashes through Parametric Human Modeling and Adaptive Design Optimization.

OBJECTIVE: Previous studies have reported disparity in injuries between male and female drivers in the risk of certain types of injuries in frontal crashes that may be due to a myriad of sex-related differences, including body size, shape, anatomy, or sitting posture. The objectives of this study are 1) to use mesh-morphing methods to generate a diverse set of human body models (HBMs) representing a wide range of body sizes and shapes for both sexes, 2) conduct population-based frontal crash simulations, and 3) explore adaptive restraint design strategies that may lead to enhanced safety for the whole population while mitigating potential differences in injury risks between male and female drivers. METHOD: A total of 200 HBMs with a wide range of body sizes and shapes were generated by morphing the THUMS v4.1 midsize male model into geometries predicted by the statistical human geometry models. Ten male and ten female HBMs were selected for population-based simulations. An existing automated simulation framework was leveraged to rapidly set up crash simulations with the morphed HBMs and previously-validated driver compartment and restraint models. A total of 1,000 frontal crash simulations were performed under varied restraint designs and crash severities. A surrogate model was developed based on the simulation data using a Gaussian Process (GP) method. Two design optimization schemes were used to flexibly adjust design parameters based on subject variables to minimize population injury risks while minimizing differences in injury risk between male and female HBMs. KEY RESULTS: The simulations indicated that the joint injury probability (Pjoint) is more sensitive to the seatbelt and driver airbag variables at 35 mph, while the variability is greatly reduced at 25 mph for all design variables. The optimal adaptive design strategy from these models suggested a higher seat belt load limit, higher airbag inflation pressure, smaller airbag venting, and higher steering column force for occupants with higher body mass index (BMI). The adaptive design reduced the population Pjoint by 19.6%, 31.8% and 38.8% from the baseline design when Delta-V equals to 25, 30 and 35 mph, respectively. For high speed crashes (Delta-V = 35 mph), the proposed adaptive design reduced the average Pjoint differences between men and women from 24.02% to 2.84% compared to the baseline design. Surprisingly, a restraint strategy constrained to sex-based balance is able to maintain similar injury risks between male and female drivers. MAJOR CONCLUSION: This study is the first to integrate finite element crash simulations with adaptive restraint design optimization to potentially reduce population injury risks and safety balance between male and female occupants. Gaussian process was shown to be an effective surrogate to FE simulations.