Brain Injury Criterion (BrIC)

Description

The Brain Injury Criterion (BrIC) uses peak head angular velocity about three axes to estimate the probability of brain injury. It complements acceleration-based measures such as HIC by representing rotational head motion [1].

When this feature is available

BrIC becomes available when either the current curve selection or any loaded test contains a head angular-velocity measurement set that meets the requirements. Only channels with a usable data status count.

The required measurement set includes:

• The signal attachment must be HEAD CG.
• The group must contain all three angular-velocity channels:
  • Axis: X - LOCAL, Units: DEGREES/SEC
  • Axis: Y - LOCAL, Units: DEGREES/SEC
  • Axis: Z - LOCAL, Units: DEGREES/SEC

WebSAT checks each occupant or test subject independently and enables BrIC if any HEAD CG group contains the complete three-axis set.

Settings

This feature has no settings.

How WebSAT processes the data

1. Validate the complete X-, Y-, and Z-angular-velocity set at HEAD CG.
2. Convert each angular-velocity component to radians per second.
3. Filter each component at CFC 60.
4. Find the maximum absolute angular velocity about each axis.
5. Normalize the three maxima by the BrIC critical velocities and calculate:

$BrIC=\sqrt{\left(\frac{\omega_{x,max}}{\omega_{x,crit}}\right)^2+\left(\frac{\omega_{y,max}}{\omega_{y,crit}}\right)^2+\left(\frac{\omega_{z,max}}{\omega_{z,crit}}\right)^2}$

6. Evaluate the AIS 1+ through AIS 5+ risk curves.
7. Report BrIC, the component maxima, and the available injury probabilities.

Reference values and injury risk

BrIC is calculated by normalizing each peak angular velocity by a critical angular velocity. The values below are the critical velocities published with BrIC [1]:

ATD	X critical velocity (rad/s)	Y critical velocity (rad/s)	Z critical velocity (rad/s)	BrIC reference value
Hybrid III 50th male	66.25	56.45	42.87	1.05
Hybrid III 5th female	66.25	56.45	42.87	1.05
THOR 50th male	66.25	56.45	42.87	1.05
ES-2re	66.25	56.45	42.87	1.05
EuroSID	66.25	56.45	42.87	1.05
WorldSID 50th male	66.25	56.45	42.87	—
Hybrid III 95th male with THOR-LX legs	66.25	56.45	42.87	—

When the selected ATD does not define critical component velocities, WebSAT uses the default values 66.25 rad/s, 56.45 rad/s, and 42.87 rad/s for X, Y, and Z. The 1.05 values shown above are the populated ATD-level BrIC assessment references; the BrIC calculation itself is governed by the three component critical velocities.

The application reports risk for AIS 1+ through AIS 5+ using the BrIC cumulative-strain-damage relationships published by Takhounts et al. [1]. The supported curves share a lower location parameter of 0.523 and use AIS-specific scale parameters. The AIS 3+ and AIS 4+ relationships are:

$P(AIS\,3+)=1-e^{-((BrIC-0.523)/0.531)^{1.8}}$

$P(AIS\,4+)=1-e^{-((BrIC-0.523)/0.647)^{1.8}}$

Results

The result summary reports BrIC, the peak X/Y/Z angular velocities and their times, and AIS 1+ through AIS 5+ probabilities. Plots show the filtered component signals and risk curves.

BrIC summary for the left- and right-front-seat occupants in test 10099.

Filtered X-, Y-, and Z-axis angular-velocity histories used for BrIC.

AIS 1+ through AIS 5+ risk curves with the calculated BrIC result marked.

References

[1] Takhounts, E. G., Craig, M. J., Moorhouse, K., McFadden, J., and Hasija, V. “Development of Brain Injury Criteria (BrIC).” Stapp Car Crash Journal, 57, 2013, pp. 243–266. https://doi.org/10.4271/2013-22-0010.