A shielding is a wall intended to protect what is behind.

Electric shielding

A electric shielding is a protection against the parasite S.

• This protection is generally inspired by the Faraday screen room, it forms a conducting envelope where the parasites electric S and electromagnetic are forwarded to the mass mechanical and electric of the device or the machine. This mass is very often connected to the Ground.
• the thickness of the known as shielding has only one effect of mechanical resistance, and does not play in the quality of protection.

Military shielding

See also: Ammunition anti-shielding

The terrestrial, air or nautical military vehicles, are often armoured in order to provide a protection to the crews during the missions carried out under enemy fire.

To fight moving, while being covered, was always a dream for the infantrymen. Already, in Antiquity and particularly at the time Roman, certain protections and techniques of protection to the combat, were invented (armor, helmet, dimension, tortoise, ect…). Some are still used nowadays, in certain cases, by the special forces, like the formation of the tortoise. But these protections remain still precarious. It is with the Middle Ages that were developed the first protections with truths armours for conveyed and conveying (soldiers and horses, at that time).

Steel

At the beginning of the 20th century, the shieldings of Acier were manufactured in plates, half-compartments with dimensions and riveted together. However, at the end of the war of 14/18 and in the small conflicts of the Thirties, the soldiers discovered that the closest Explosion S as of the surface blows jump the Rivet S. Those often managed to make ‑ Ci were ejected in the cockpit or they rebounded with the effects which one imagines. The plates then were welded together or, better, one ran them of only one part.

Today, the shielding steel of the tanks is cast in some large parts of several tons. The system of moulding and treatment produces a special hardening on external surface. This hardened side diverts the shells or makes burst the weakest loads. The less solid texture of the interior ensures than in the event of penetration of surface, the whole of the shielding will not burst. The interior of the structure is often covered of Kevlar or another “ballistic” product, which prevents the diffusion of fragments of shielding or shell inside the tank in the event of penetration. This ballistic coating is supposed to stop at least the largest fragments, thus reducing the damage and the wounds inflicted by a penetration.

Inclined shielding, round shielding

Since the famous T ‑ 34 (produced in 1941), the tanks used the shieldings inclined to increase the real thickness of their protection, but also the rebounds of the shootings. One of the first remedies against heads HEAT was to change the shape of the armor-plates. Instead of assembling the plates with right angle, in the Fifties, the bodies and the turrets of the tanks were drawn with angles rounded. This shielding made it possible the blows to better rebound, or at least shells HEAT and their gas jet to rather strike the shielding according to an angle which would deviate the jet in the air, than in the middle of the tank. Of course, a shooting of HEAT of full whip remains fatal.

Composite shieldings

The composite shieldings and Chobham were invented in the Sixties ten. This type of shielding is made layers of metal to high density/high strength and plastic ceramics of high heat strength. The nonmetal layers play the part of traps with heat or reflectors, reducing the temperature of the gas jet much more quickly than metal. That wants especially to say that the jet penetrates less deeply.

Usually, the composite shielding has a surface external of chilled steel, like the normal shieldings. But in lower part, one finds layers successive of metals and ceramics. On the Abrams, the first layer, external, is out of inert, a substance almost twice and half uranium harder than steel. Other layers follow, made up of ceramics and metals. Ceramics resists heat better, and metals resist the kinetic energy better. The total effect, it is that of a shielding which resists the kinetic energy at least as well as a traditional shielding, and which absorbs the jet burning of shells HEAT so that they become almost useless about it.

The interior layer of the shielding, is a plastic or a special metal resistant to the bursting at least as well as the “ballistic” fabric.

The exact mixture of the Chobham shielding is more complex than a simple stacking. Ceramics can be cast in a structure in honeycomb, or the opposite. The layers can come one on the other or overlap according to complex systems.

All the composite shieldings have in common that they are manufactured in plates. The tanks which “adopt” this new shielding must give up the round forms and return to the acute angles. From where profile with the knife of the Tank M1 Abrams, the tank Leopard II and the frame before series T-72 and T ‑ 80 Russian.

Reactive shielding

On their side, the Israéliens developed a reactive defense against the hollow-charges and papering surface external of the vehicle of small boxes filled with explosive.

Advantages

Insensitive with the Shrapnel and the ball S, the explosion of these containers deviates the action of a hollow-charge, making inoperative the gas jet of the load. That reduces of much the penetration of the shielding. The Israelis call that a shielding “Blazer”. The reactive shielding can be adapted to almost all the types of shieldings. It gives to the vehicle a good protection against the HEAT.

Disadvantages

This thickness of “boxes” can trap the shells and still deviate them towards other parts of the tank, sometimes more vulnerable. Then, as soon as a container was struck by a load, the tank loses, at this place, its protection and becomes vulnerable if a shooting strikes at the same place. Lastly, last disadvantage, the tank transports also equipment and often of the personnel outside, very close to these boxes. Moreover, the reactive shieldings resist less better the shells with high swiftness. The boxes explode without really being able to stop the head of the shell which carries on its way.

Parades the improved loads

To fight the reactive shielding, of new heads HEAT were invented. The head “on two floors” has a small explosive load at the end of a probe. This load is supposed to put out of state the reactive shielding. Of course, it (good) load follows and attacks the shielding exposed again. Today, missile TOW 2 has a head of this kind.

The other technique consists in increasing the diameter of head HEAT. That creates a gas jet even more powerful, which makes it possible to compensate for the reactive explosion, or to penetrate more deeply in composite materials. The head of the Hellfire missile was designed in this direction.

Light alloys

Some light tanks and much of light AFV (transport of troops) gave up steel for light metal alloys. The Aluminum is one of most common. For example, the Americans use aluminum for their M113 and their M2/M3. Russia even used magnesium alloys for certain parts of its BMP. In both cases, that was not a big hit. These metals have a melting point quite lower than that of steel. When they are penetrated, of the fragments of the shielding take fire literally, diffusing fused metal around the vehicle. In Afghanistan, the BMP on fire were very common. The bad choice of the place of the tanks contributed much obviously to the annoying tendency which had the BMP to transform into torch.

Consequential damages

One does not know large thing of the quantity of damage inflicted by a nonpenetrating shooting. During the Second world war, a shooting of this kind could wound or kill the crew very well, in particular for the tanks which used a shielding with rivets. The welded or moulded tanks passed the test certainly best, but the crew was still seriously wounded by the shock, the interior glares of shielding slipping by everywhere in the tank starting from the point of impact. Moreover, the tanks of the Second world war drew with guns from gauge ranging between 50 and 85 Misters the current shells reach gauges from 120 to 125 mm and carry a double load or triple. Even with coatings anti-glares and new composite shieldings, a blow with the goal which penetrates partly the shielding can cause very destroying side effects.

The consequential damages can be important in the case of Abrams reached by a ATGM ( Anti-Tank Guided Missile ) or a HEAT. By neglecting the consequential damages, Abrams resists the drawn missiles on its front, because they are not likely practically any to penetrate. However, the consequential damages will be able to wound to see killing the team members and certainly causing many other damage.

Civil shielding

Of iron work, the Blindage consists in reinforcing a door, a window, a shutter or its door frame by means of metal protections offering a resistance increased to the effraction. The metalliers direct themselves today towards the manufacture of block-doors; Block-Carries is a door frame unit/carries out of metal with hinge plates to welded balls. There exists a great number of means contributing to the shielding of a door like the angles anti grips, the dishes of beats, the bars of threshold etc

Shielding in public works

At the time of the opening of a trench, the shielding consists in supporting the walls in order to avoid a collapse of those. Various criteria return in account on the need for armouring an excavation: Depth, nature of the ground, vibrations close, hydrological conditions,… In all the cases, and the framework of in-depth excavation work for the installation of drains, the shielding ensures the safety of the workmen (pipelayers in particular) against the burial or the hiding. It is legally obligatory of " blinder" a trench as from the moment when it atteind a higher depth or equalizes with one meter thirty of depth (NFrançaise); nevertheless, the canalizing ones must be conscious of the risk of burial to less depths insofar as they are likely to work squatted.

External bonds

• Canadian Patent of a shielding anti-projectile to hollow-charge

Random links:

Christian Spitz | The Prisoner of Zenda | FMT 95.2 programs Europe 2 | Fabio Biondi | Palazzo d' Italia