Restraint System Optimizations Using Diverse Human Body Models in Frontal Crashes

Objective: This study aimed to optimize restraint systems and improve safety equity by using parametric human body models (HBMs) and vehicle models accounting for variations in occupant size and shape as well as vehicle type.

Methodology: A diverse set of finite element (FE) HBMs were developed by morphing the GHBMC midsize male simplified model into statistically predicted skeleton and body shape geometries with varied age, stature, and body mass index (BMI). A parametric vehicle model was equipped with driver, front passenger, knee, and curtain airbags along with seat belts with pretensioner(s) and load limiter and has been validated against US-NCAP results from four vehicles (Corolla, Accord, RAV4, F150). Ten student groups were formed for this study, and each group picked a vehicle model, occupant side (driver vs. passenger), and an occupant model among the 60 HBMs. About 200 frontal crash simulations were performed with 10 combinations of vehicles (n = 4) and occupants (m = 8). The airbag inflation, airbag vent size, seatbelt load limiter, and steering column collapse force were varied to reach better occupant protection. The joint injury probability (Pjoint) combining head, neck, chest, and lower extremity injury risks was used for the design optimization. Injury risk curves were scaled based on the skeleton size and shape of each HBM.

Results and Conclusions: We observed that tall and heavier male occupants tend to strike through the airbag leading to higher head injury risk; older and female occupants tend to sustain higher chest injury risk, while obese occupants tend to have higher lower extremity injury risk. After design optimizations, the average Pjoint was reduced from 0.576 ± 0.218 to 0.343 ± 0.044. The airbag inflation and venting were found to be highly effective in head protection, while the belt load limit and steering column force were sensitive to chest injury risks. Conflicting parameter effects were found between head and chest injuries and among different occupants, highlighting the complexity of achieving safety equity across a diverse population. This study demonstrated the benefit of adaptive restraint systems for a diverse population.