Active Thermal Management for Cooler Body Armor

Monday, June 01 2009

The military places greater demands on its equipment — electronic and otherwise — than any other market segment. It is also true that it places its greatest thermal demands on the men and women who serve in the armed forces. In cold environments, body armor acts as thermally protective clothing to keep a soldier warm, but in hot climates where removing body armor to cool the human is not practical or advisable, another solution is required.

Humans have been wearing armor for thousands of years. In earliest times, men wore animal skins and over time, this evolved into the wearing of metal plates, which could protect against more energetic projectiles, but only at the expense of increasing their thickness and weight.

In the 1960s, engineers developed a reliable bullet-resistant armor that a person could wear comfortably. Unlike traditional armor, this soft body armor was not made out of pieces of metal; it was formed from advanced woven fibers that can be sewn into vests and other soft clothing (see photo).

Modern body armor is divided into two main categories: hard body armor and soft body armor. Hard body armor, made out of thick ceramic or metal plates, functions basically the same way as the iron suits worn by medieval knights — it is hard enough that a bullet or other weapon is deflected. That is, the armor material pushes out on the bullet with the same force (or nearly the same force) with which the bullet pushes in, so the armor is not penetrated.

Typically, hard body armor offers more protection than soft body armor, but it is much more cumbersome. Police officers and military personnel may wear this sort of protection when there is high risk of attack, but for everyday use, they generally wear soft body armor, flexible protection that one wears like an ordinary shirt or jacket.