Head Resultant Acceleration

Overview

Head Resultant Acceleration represents the net magnitude of acceleration experienced by the head [1]. This metric can be used to understand the intensity of acceleration, but without any directional information [1]. Additionally, if there is an Injury Assessment Reference Value (IARV) associated with the ATD used in the selected load test, the calculated maximum resultant acceleration will be returned as a percent of the IARV [2]. The IARV represents a threshold value used to evaluate the risk of injury during an impact, each ATD has their own IARV value depending on the type, sex, and size of the dummy [2].

Required Signals

• Head Linear Acceleration at Head CG ($a_{x}$, $a_{y}$ and $a_{z}$)

Calculation

1. Calculates the resultant head acceleration from ($a_{x}$, $a_{y}$ and $a_{z}$)

$$Resultant\,Head\,Acceleration = \sqrt((a_{x})^2 + (a_{y})^2 + (a_{z})^2)$$

2. The calculated resultant head acceleration is filtered at CFC = 1000.
3. Converts the filtered resultant head acceleration to G's ($1\:G = 9.81\:m/s^2$)
4. Finds the maximum filtered resultant acceleration
5. Calculates the percent of the IARV that the measured maximum filtered resultant head acceleration reaches

BrIC IARV Table [3] [4]

ATD	IARV (gravity)
CRABI – 6mo	156
CRABI – 12mo	154
CRABI – 18mo	160
HIII – 3yo	175
HIII – 6yo	189
HIII – 10yo	189
HIII – F05	193
HIII – M50	180
HIII – M95	175
THOR - M50	117
SID-II	193
BioSID	180

References

[1] Huang Z., Zhang B., Wang L., Liu C. "Experimental Study on Side Pole Collision and Deformable Barrier Collision of Car". Journal of Physics Conference Series, 2020 June; 1549(3):032120.

[2] "Side Impact Crashworthiness Evaluation". Guidelines for Rating Injury Measures (Version III), Insurance Institue for Highway Safety, May 2014.

[3] Yoganandan, Narayan, et al. "Accidental Injury". Biomechanics and Prevention, 3rd edition. Springer, 2020.

[4] "Anthropomorphic Test Devices; THOR 5oth Percentile Adult Male Test Dummy". National Highway Traffic Safety Administration, 49 CFR Part 562, Docket No. NHTSA-2023-0031.