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How Body Armor Works (A technical look)

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What Is Body Armor?

As you may very well know, body armor is a protective, ballistic gear worn to prevent injury from small arms fire, knife attacks, shrapnel, ricochets, other projectiles and similar life-threatening hazards. Body armor plates are worn inside of a plate carrier, which is often called a “bulletproof vest.”

Body armor is available in a number of different styles, shapes, protection levels, weights, types, sizes and options. While soft body armor and lower levels of hard armor can provide protection from handgun rounds, only hard body armor can stop rifle rounds.

Take a look at some of the modern body armor systems available at Spartan Armor, which include a number of level 3a body armor options.

How Body Armor Works

The basic principle behind how body armor works involves the simple transfer of energy. When struck by a bullet round, body armor plates are designed to spread the energy and deform the bullet, which greatly reduces blunt force trauma to vital organs.

Body armor plates are made up of strong fibers that are tightly woven in a perpendicular weave to create a solid sheet of material. The fibers are often twisted to increase strength, density and thickness. To make the body armor plate more solid, it is coated with resin, plastic and/or other materials.

When singular fibers are interlaced, they strengthen each other and provide protection from all directions.

When a bullet or projectile hits a surface constructed of this strong webbing, there is a transfer of energy from the bullet to the surface. The surface area absorbs the energy coming from the point of impact, spreading it across the entire surface area. This means that the impact isn’t felt in just one particular spot. While the wearer will still experience the bullet’s impact, it will be felt over a much larger area, which reduces the chances of a serious injury.

Each layer of interwoven material in the body armor plate absorbs the energy from the projectile. Because all of the fibers are intertwined, all of the fibers are reinforcing each other within that layer – along with the layers behind it. Each layer of webbing slows the bullet down a bit more, until the bullet is stopped completely. This also causes the bullet to deform and “mushroom.”

In general, the more layers of ballistic material in your body armor, the more protection it will provide.

Which Fibers Are Used in Body Armor?

Instead of using metal, soft body armor is usually formed from strong woven fibers that can be sewn into vests and clothing. The most recognized material used for making soft body armor is Kevlar.

Kevlar is a lightweight fiber that is 5x stronger than a steel fiber. When Kevlar fibers are interlaced and layered, they can absorb a lot of energy and force.

Vectran is another man-made fiber which is spun from a liquid-crystal polymer. It is known to be 2x as strong as Kevlar. Vectran is also 5-10x stronger than steel.

Spider silk has inspired a material called Biosteel, which is being produced by transgenic goats. This strong, fiber-based material is made of the recombinant spider silk-like protein extracted from the milk of these goats. A Biosteel fiber can be up to 20x stronger than a steel fiber.

Hard body armor consists of hard ceramic or metal panels, which are built from layers of superior strength materials such as ceramic/composite and titanium. Of course, hard body armor plates can offer much more protection than soft body armor.

Ceramic/composite hard body armor continues to grow in popularity, exceeding metal hard armor systems. The ceramic used in body armor is called aluminum oxide or alumina (Al2O3). This chemical compound is extremely hard with a high melting point. Ceramic/composite body armor plates usually combine alumina with an UHMWPE (ultra-high-molecular-weight polyethylene) or aramid backing to create much higher ballistic protection from more advanced rifle threats. UHMWPE and aramid are extremely tough materials that are also placed into sheet layers and stacked to provide strength in all directions.

Some manufacturers may also use plastic polyethylene, which is lighter, thicker and weaker than ceramic.

To ensure that body armor plates work as intended, they are put through a testing process by the National Institute of Justice (NIJ). This testing process determines whether or not the body armor will keep you protected and stop the bullet rounds it is meant to.

NIJ Body Armor Testing Process

In the US, body armor levels are created and certified by the National Institute of Justice, an agency of the US Department of Justice. The National Institute of Justice is the only ballistic body armor testing authority that is nationally recognized by US law enforcement and military.

The NIJ test standard is called the Ballistic Resistance of Body Armor NIJ Standard-0101.06. The standard determines the threat levels, along with the caliber and velocities that each level can protect against. For body armor to earn an NIJ certification, it must pass all of the NIJ stringent testing protocols. Most testing uses 14+ sets of body armor, but for levels IIA, II and IIIA, 28 sets of panels are tested. Some panels are even soaked in water and dried before testing.

The ballistic threat levels are I, II-A, II, III-A, III and IV. I is the weakest and IV is the strongest.

Level III rated body armor is the most popular body armor on the market. For the highest level III protection available, check out Spartan Armor Systems AR550 Level III+ Body Armor and 221B Tactical Phantom Plate Carrier. We also carry packages such as the Level III+ AR550 Certified Plates and Sentinel Plate Carrier Package.

For NIJ testing, a body armor plate is placed on a clay backing and a steel sphere is dropped from specific heights to ensure the plate will deflect the projectile at a specified force. The body armor plate is also placed in a Kevlar-layered fabric, which replicates a plate carrier. This is known as a “shoot pack.”

The body armor plate is shot with specified calibers and velocities.

The body armor is then inspected to ensure it hasn’t been penetrated and the dents in the clay aren’t too deep. 43mm is the maximum allowable depth.

Looking Forward

As technology continues to improve and body armor manufacturers continue researching materials for lighter, more effective materials and configurations, body armor is sure to improve. The market for modern body armor continues to grow as more and more people realize its benefits.

Researchers are now looking for other materials for constructing body armor. “Liquid body armor” or sheer thickening fluids are made of liquid, polyethylene glycol and hard silica particles. The US Army is currently testing pre-soaked STF Kevlar body armor.

Hagfish slime is being researched for soft body armor because of its strength and flexibility. Some believe that slime body armor will be lighter and stronger than Kevlar.

Composite metal foams (CMF) are currently being tested as hard body armor and are known to turn 7.62mm AP rounds to dust.

Learn more about advancements in body armor in this blog.

Do you have anything to add about how body armor works? Leave us a note in the comments section below.



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