Vehicle armour

Military vehicles are commonly armoured (or armored; see spelling differences) to withstand the impact of shrapnel, bullets, shells, rockets, and missiles, protecting the personnel inside from enemy fire. Such vehicles include armoured fighting vehicles like tanks, aircraft, and ships.

Civilian vehicles may also be armoured. These vehicles include cars used by officials (e.g., presidential limousines), reporters and others in conflict zones or where violent crime is common. Civilian armoured cars are also routinely used by security firms to carry money or valuables to reduce the risk of highway robbery or the hijacking of the cargo.

Armour may also be used in vehicles to protect from threats other than a deliberate attack. Some spacecraft are equipped with specialised armour to protect them against impacts from micrometeoroids or fragments of space debris. Modern aircraft powered by jet engines usually have them fitted with a sort of armour in the form of an aramid composite kevlar bandage around the fan casing or debris containment walls built into the casing of their gas turbine engines to prevent injuries or airframe damage should the fan, compressor, or turbine blades break free.

The design and purpose of the vehicle determines the amount of armour plating carried, as the plating is often very heavy and excessive amounts of armour restrict mobility. In order to decrease this problem, some new materials ( nanomaterials) and material compositions are being researched which include buckypaper, and aluminium foam armour plates.

Materials

Metals

Steel

'' Rolled homogeneous armour'' is strong, hard, and tough (does not shatter when struck with a fast, hard blow). Steel with these characteristics are produced by processing cast steel billets of appropriate size and then rolling them into plates of required thickness. Rolling and forging (hammering the steel when it is red hot) irons out the grain structure in the steel, removing imperfections which would reduce the strength of the steel. Rolling also elongates the grain structure in the steel to form long lines, which enable the stress the steel is placed under when loaded to flow throughout the metal, and not be concentrated in one area.

Aluminium

''Aluminium'' is used when light weight is a necessity. It is most commonly used on APCs and armoured cars. While certainly not the strongest metal, it is cheap, lightweight, and tough enough that it can serve as easy armour.

Iron

Wrought ''iron'' was used on ironclad warships. Early European iron armour consisted of 10 to 12.5 cm of wrought iron backed by up to one meter of solid wood. It has since been supplemented by steel due to steel being significantly stronger.

Titanium

Titanium has almost twice the density of aluminium, but can have a yield strength similar to high strength steels, giving it a high specific strength. It also has a high specific resilience and specific toughness. So, despite being more expensive, it finds an application in areas where weight is a concern, such as personal armour and military aviation. Some notable examples of its use include the USAF A-10 Thunderbolt II and the Soviet/Russian-built Sukhoi Su-25 ground-attack aircraft, utilising a bathtub-shaped titanium enclosure for the pilot, as well as the Soviet/Russian Mil Mi-24 attack helicopter.

Uranium

Because of its high density, depleted uranium can also be used in tank armour, sandwiched between sheets of steel armour plate. For instance, some late-production M1A1HA and M1A2 Abrams tanks built after 1998 have DU reinforcement as part of the armour plating in the front of the hull and the front of the turret, and there is a program to upgrade the rest (see Chobham armour).

Plastic

''Plastic metal'' was a type of vehicle armour originally developed for merchant ships by the British Admiralty in 1940. The original composition was described as 50% clean granite of half-inch size, 43% of limestone mineral, and 7% of bitumen. It was typically applied in a layer two inches thick and backed by half an inch of steel.

Plastic armour was highly effective at stopping armour piercing bullets because the hard granite particles would def