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.
