Composite armour
From Wikipedia, the free encyclopedia


Composite armour is a type of vehicle armour consisting of layers of different material such as metals, plastics, ceramics or air. Most composite armours are lighter than their all-metal equivalent, but instead occupy a larger volume for the same resistance to penetration. It is possible to design composite armour stronger, lighter and less voluminous than traditional armour, but the cost is often prohibitively high, restricting its use to especially vulnerable parts of a vehicle.

The most common type of composite armour today is Chobham armour, first developed and used by the British in the experimental FV 4211 tank, which was based on Chieftain tank components. Chobham sandwiches a layer of ceramic between two plates of steel armour, which was shown to dramatically increase the resistance to high explosive anti-tank (HEAT) rounds. HEAT had posed a serious threat to armoured vehicles since its introduction in WWII, and Chobham was such an improvement that it was soon used on the new U.S. M1 Abrams main battle tank (MBT) as well. It is the fabrication of the ceramic in large tiles that gives the Challenger and Abrams their "slab sided" look.

Chobham's precise mechanism for defeating HEAT was something of a mystery until the 1980s. High speed photography showed that the ceramic material shatters as the HEAT round penetrates, blowing up to a huge volume which then expands back out the hole and pushes the metal jet of the HEAT with it. The effectiveness of the system was amply demonstrated in Desert Storm, where not a single British Army Challenger tank was lost to enemy tank fire. Chobham-type armor is currently in its third generation and is used on modern western tanks such as the British Challenger 2E and the American M1A2 SEP Abrams.

The first widespread use of a composite armour appears to have been on the Soviet T-64. It used an armour known as Combination K, which apparently is glass reinforced plastic sandwiched between inner and outer steel layers. Through a mechanism called thixotropy, the resin changes to a fluid under constant pressure, allowing the armour to be moulded into curved shapes. Later models of the T-64, along with newer designs, used a boron carbide-filled resin aggregate for greatly improved protection. However the quality of the tanks produced during this era varied widely; if the boron carbide was not available in time to meet production quotas, the tank would be shipped with any filler that could be found, and sometimes nothing at all. In order to deal with these problems, the Soviets invested heavily in reactive armour, which allowed them some ability to control quality.

Composite armour has since been applied to smaller vehicles, right down to jeep-sized. Many of these systems are applied as upgrades to existing armour, which makes them difficult to place around the entire vehicle. Nevertheless they are often surprisingly effective; ceramic upgrades to Canadian M-113s were carried out in the 1990s, after it was realized that it would offer more protection than newly built APCs like the M2 Bradley.

Odlicno- jos da si naso neki presek...

Evo vam dva starija patenta posle male google akcije. Imam par naucnih papira na datu temu ali oni nisu bas za popular-science level - if you know what I mean 

BAzican princip skoro svakog pasivnog oklopa se zasniva na tri stvari

- tvrdoca
- zilavost
- rasipanje i preusperavanje energije udara

Posto ni jedan materijal poznat coveku nema sve tri ososbine sasvim je bilo jasno jos 70tih da je kompozitni oklop resenje. Ima milion i jedan nacin kako ovo da se resi i ni jedno resenje nije najbolje jer uvek postoji neka vrsta penetratora koja lakse prolazi kroz jedan oklop od drugog. Najbolja primena ove tri osobine oklopa je otprilike ovako. Gornji sloj oklopa koji je prvi u kontaktu sa penetratororm mora da bude visoke tvrdoce (keramika - uglavnom razni nitridi i karbidi). Ravne ploce su se koristile na pocetku ali su se pokazale kao dosta lose jer su bile skupe i veoma tanke. Cilje je da je prvi impuls udara reflektuje od mete i time smanji inicijelna kineticka energija penetratora. Naravno i penetratori se prave sa glavama od keramike tako da jedan sloj na oklopu ne znaci nista. Caka ovde je koristiti vishe slojeva keramickih kugli - tako da se cak pri prvom kontaktu izmedju oklopa i penetratora energija udara rasipa na veliku povrsinu jer kugle interakcijom izmedju sebe raspodeljuju energiju i prenose je iza sebe na vecu  povrsinu. Kugle su uvek u nekoj plasticnoj smoli da bi prenos energije bio sto bolji. Ispod keramike se obicno stavlja vlaknasti kompozit jer jaka staklena vlakna (S staklo) ili kevlar (aramid) transformisu energiju koja dolazi duz vektora normale na povrsinu u energiju koju absorbuju vlakna duz vertora paralelnog sa povrsinom oklopa. Povrsina prenosa energije je na ovom sloju jos veca. Na kraju je potreban materijal koji je dovoljno zilav i jak da se deformise ali ne bude probijen i svojom plasticnom deformacijom zaustavi penetrtaor. Jedini materijal dovoljno dobar za ovo je stari dobri celik.

Ko sto rekoh postoje varijacije na temu - tipa celija sa vazduhom pod pritiskom rasnoraznih hibridnih kompozita itd itd - sve je pitanje tezine, debljine, namene i cene oklopa. Prosecne tezine oklopa ovog tipa ido od 5kg/sqm pa i do 30kg/sqm.   

To je to Decky Ne brini za apire, nema potrebe da iznosis to... imao sam i ja tako nesto al koja je svrha svi ti dijagrami, tabele, podaci o materijalima...