The concept of armor is thousands of years old, with the earliest forms of personal armor being made during the Shang Dynasty in China about 3,600 years ago. Their armor was made of leather and turtle shells but we cannot really consider that to be a composite. Greek bronze armor was the next real step forward, with the earliest shoulder protector dating back 3,500 years. Of course, shields are technically a form of armor, and the oldest shields date from this time.
Wood and leather were common materials used for shields not only on the grounds of cost but also because of weight. Then, iron and steel came into use and chain mail was produced, together with the ‘suit of armor’ which was used in medieval times.
Weight has always been a key factor in armor design. Steel armor in early 20th Century battleships could be as much as 18” thick and weighing thousands of tons. This imposed huge design constraints on these ships. Weight is an important aspect of armor even today, and one aspect in which advanced composite materials offer significant advantages.
Design Principles and Concepts
Armor can be designed to be used in several ways and the principles have applied across the centuries: ballistic protection against arrows, bullets and shrapnel; deflection to deflect sword blows or bomb blasts; thermal armor to protect against heat or thermal weapons such as flamethrowers. Nowadays, armors are being designed to protect against laser weapons.
One important note here: not all armor produced is for military purposes or protection against malicious agency. In its most general interpretation, armor is also used in civilian applications. For example, armored electrical cable has a shielding casing to protect against accidental damage and flexible composites are used for this.
Types of Armor Systems
The concept of shields is still relevant. Even though we think of most armor as being personal or related to military vehicles, warplanes and naval vessels there are other applications too: shielding for buildings and critical infrastructure.
Reinforced concrete is a composite used for shielding, but modern composites are used too, not so much as a structural shielding material, but as cladding to provide ballistic protection or explosive blast deflection.
Other shielding concepts include ballistic (drape or curtain) systems to protect conference rooms, offices, embassies, machine rooms and other sensitive assets. Fragmentation blankets are used as a simple portable grenade-proof protection solution.
Most personal armor, in the form of ‘ballistic vests’ and ‘stab vests’ use advanced composite aramid fiber materials (Kevlar™, Twaron™). Helmets are molded from Kevlar/epoxy composites. The jackets often include provision for ‘trauma plates’ which offer additional protection typically for the chest and spinal areas of the body. These plates have typically been made of steel or titanium, but are now being replaced by layered ultra high molecular weight polyethylene (‘UHMWPE’) layered with foam. Ceramic composites may also be used.
The ultimate personal armor is, of course, worn by ordnance experts who defuse IEDs and other explosive devices. The design concept behind this is leading to newer formats of personal armor which integrate large numbers of small trauma plates into the regular battledress. Ceramic composite armor used in battle-tanks follows this principle too, with large numbers of small plates.
At the high end of armor technology, the secret ceramic composite armor which is highly effective and defeats high explosive anti-tank weapons – even sabot penetrators.
Regular advanced composite armor is being integrated into the design of military vehicles, and concepts such as ‘blast chimneys’ are being utilized. These direct the blast from underfloor explosions up through an armored funnel (‘chimney’).
The significant weight savings and manufacturing flexibility of composites mean that a much higher level of protection can be provided without loss of performance or payload reduction. Remember, it is almost equally important for a military vehicle to quickly escape an ambush, as it is to protect from munitions. Composite armor is the only solution that can provide both.
From the perspective of traditional weapons, composites are here to stay. Their light weight, tailorable physical properties and the ability to manufacture armor components to a specific shape using a variety of process from simple lay-up to compression molding means that they can be easily integrated into a structural design.
Composite armor plates are now almost a military commodity, supplied in bulk for flexible deployment – a concept that could not have been contemplated with steel armor. Composites are changing the way that armor is deployed, analogous to the way that ‘containerization’ changed military logistics forever.
Carbon nanotubes and nanocomposites offer tremendous possibilities for trauma plates and ballistic fabrics, and we will see these come into production in the very near future.
Armor has to keep pace with weapons technology, but practical personal armor to protect against advanced weapons such as x-ray lasers and neutron weapons is still well over the horizon.