The objective of this study is to use parametric human body models (HBMs) to
understand how geometric variability among individuals who have the same sex,
stature, and body weight may affect the impact responses and injury outcomes,
using midsize male and midsize female populations as representative cases.
Methods were developed to quantify skeletal and external body surface variations
using principal component analysis, regression, and residual error analysis.
Based on this analysis, nine midsize male and nine midsize female geometric
models were created, focusing on ribcage and pelvis variations, which account
for most of the observed variability. These geometries were then applied to
morph the simplified Global Human Body Model Consortium (GHBMC) midsize male
model, producing 18 distinct HBMs. Each morphed HBM was subjected to nine impact
scenarios, resulting in a total of 162 simulations to assess the effects of
geometric variability.
Substantial geometric variation was observed in the ribcage and pelvis, while the
femur and tibia showed minimal variability for both midsize males and females.
All morphed HBMs had good mesh quality, and all crash simulations terminated
normally without error. Component-level tests showed relatively minor
differences in impact responses among HBMs with identical sex, stature, and body
weight. However, the United States New Car Assessment Program (US-NCAP) frontal
crash simulations revealed considerable differences in injury risk, especially
in the front passenger position.
These findings highlight the importance of accounting for geometric variability,
even among HBMs with the same sex, stature, and body weight, when evaluating
injury risks in severe frontal crashes. It is especially important to consider
ribcage geometry variations, which could impact occupant sitting height,
posture, and injury risks at different body regions in frontal crashes. This
study demonstrated that future virtual testing frameworks using HBMs should
consider human geometric variations, especially in the ribcage and pelvis, when
assessing injury risks in vehicle frontal crashes.
