Composite armour

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, use a boron carbide-filled resin aggregate for greatly improved protection[citation needed] .

The need to mount multiple angled plates, along with an outer steel layer to protect the armour array, gives the Challenger and Abrams their "slab sided" look.

The outer steel "burster" plate detonates the shell and protects the composite array from the blast, increasing the armour's multi hit abilities.

The elastomer quickly reaches maximum compression and rapidly expands, pushing the two steel plates in opposite directions.

(However, one was destroyed by friendly fire on March 25, 2003, killing two crew members after a HESH projectile detonated on the commander's hatch causing high-velocity fragments to enter the turret.

The German Leopard 2A5 featured distinctive arrowhead laminated armour modules that was mounted directly onto the turret composite arrays, increasing protection markedly above the previous 2A4 model.

Nevertheless, they are often surprisingly effective; upgrades with MEXAS ceramic armour to Canadian M113s were carried out in the 1990s, after it was realized that it would offer more protection than newly built IFVs like the M2 Bradley.

[citation needed] In 2004, American Marvin Heemeyer used an ad hoc composite armour on his Komatsu D355A bulldozer ("which he called the MK Tank and in popular culture, the Killdozer") used in a rampage in response to a dispute with the city he lived in over a zoning issue.

The armour, at some places a 1 foot (30 cm) thick, consisted of a layer of concrete sandwiched between layers of steel, successfully rendering the vehicle impervious to small arms fire and small explosives used by law enforcement in an attempt to stop the vehicle.