Science of Impact Mitigation (2/2)

By­ reading Part 1 of this blog series, you learned the different blunt force levels associated with sports, space shuttle launches, military standards, and mild Traumatic Brain Injuries (mTBI). Next, what is the primary goal of a helmet, be it military or other, and how does it accomplish this goal.
 

Helmets v. Force

The primary job of a helmet during any given impact is to keep head acceleration below acceptable levels. To do this, any good helmet engineer should be able to recite Newton’s second law, or at least what it boils down to; f=ma, force equals mass times acceleration.

The mass of your head is (more or less) a constant, so it really comes down to the force that the helmet “pushes back” on your head to determine the acceleration your head experiences. This is like putting the brakes on a speeding car, and in a helmet it happens in a split second as your head compresses into the padding or liner of the helmet.

Some people first think of the outer shell of a helmet as the important part, many times we’ve seen someone pick up a helmet and flex the shell to get an idea of its’ strength, but while the shell does have an important job (particularly for ballistic helmets) and works together distributing impact loads over the padding and surface of your head, it’s ultimately the way the padding responds under compression that actually puts the brakes on your head. Things get complicated with the uneven curvature of the head, the variety of head sizes, impact conditions and locations, and the need to consider a range of g thresholds, but know that it all comes down to f=ma.

Here at Team Wendy we’ve put a significant focus on developing materials that provide the best possible performance in mitigating blunt impact, with precisely tuned compressive responses to keep head accelerations as low as physics will allow. We engineer this performance into every product.
Of course blunt impact alone doesn’t tell the full story of what our helmets can do. Stay tuned to find out more, including new approaches to rotational impacts, blast overpressure, and ballistic threats.