Head impact criterion
From Wikipedia, the free encyclopedia
The Head Injury Criterion (HIC) is a measure of the likelihood of head injury arising from an impact. Normally the variable is derived from the acceleration/time history of an accelerometer mounted at the centre of gravity of a dummy’s head, when the dummy is exposed to crash forces.
![\mathit{H}\mathit{I}\mathit{C} = \bigg\{ \left ( t_{2}-t_{1}\right ) \Big[ \frac{1}{t_{2}-t_{1}} \int_{t_{1}}^{t_{2}} a(t)dt\Big]^{2.5}\bigg\}_{max}](../../../../math/4/3/d/43d03d552d374955c31696ce798a780a.png)
where t1 and t2 are the initial and final times (in seconds) of the interval during which HIC attains a maximum value, and acceleration is measured in g's. Note also the maximum time duration of HIC is limited to a specific value, usually 15 ms.
This means that the HIC includes the effects of head acceleration and the duration of the acceleration. Large accelerations may be tolerated for very short times.
At a HIC of 1000, one in six people will suffer a life-threatening injury to their brain (more accurately, an 18% probability of a severe head injury, a 55% probability of a serious injury and a 90% probability of a moderate head injury to the average adult)[3].
