Parametric Analysis and Optimization of Variables Affecting the Brain Injury Criterion (BrIC) in Various Crash Scenarios

Incompressibility of the brain makes it susceptible to damage from shear strains. Head rotational motion can easily produce high shear strains causing brain injury. Since head injury criterion (HIC) does not account for rotational motion, a brain injury criterion (BrIC) was developed. To design potential countermeasures for reducing BrIC, it is important to investigate the parameters that influence BrIC. This article focuses on parametric analysis to examine the sensitivity of BrIC to vehicle design and crash-related parameters, and identifying important parameters which can be controlled in developing countermeasures for reducing BrIC. Global Human Body Models Consortium (GHBMC) 50th percentile male simplified human finite element (FE) model was used in this study. Four different analyses were conducted:

1. a
   Design of Experiments (DOE) study to investigate sensitivity of BrIC to impact direction and crash pulse severity
2. b
   DOE studies, with fixed crash severity, for frontal, far side oblique, and near side oblique crash modes to identify important vehicle design parameters influencing BrIC
3. c
   Optimization for frontal, far side oblique, and near side oblique crash modes to minimize BrIC using important parameters (identified from step b) as design variables
4. d
   Investigate greater frontal airbag coverage as a possible countermeasure.

The results demonstrated that

1. a
   BrIC was most sensitive to principal direction of force (PDOF) and crash pulse severity
2. b
   With fixed crash severity, the important vehicle design parameters affecting BrIC were the frontal airbag parameters (mass flow rate (MFR), firing time, friction), belt load limiter, and side airbag friction
3. c
   Low BrIC values could be attained for each crash mode with the highest optimized BrIC of 0.59 for the far side driver oblique crash mode (representing 1.67% risk of Abbreviated Injury Scale (AIS) 4+ brain injury), and under 0.5 (representing 0% risk of AIS 4+ brain injury) for the full-frontal and near side driver oblique crash modes;
4. d
   Significant reduction in BrIC values was possible with increased frontal airbag coverage.