How does composite armour work?

[Nikitin]

Hi, I noticed that most modern tanks have barely any slope on their armour, unlike for example the old WW2 tanks like the T-34 using solid steel armour.

Why exactly is this? Why is sloping of armour gone? I realize that modern armour isn't trying to deflect a shell, but still if armour is sloped 60 degrees from vertical, it would, from a horizontal perspective, be 2x thicker.

Only a few tanks have sloped armour, a few Israeli and Russian ones.

 

[fss]

Different materials have different characteristics than steel when it comes to mitigating the damage from tank shells. I believe the details of the Chobham armor on the M1A1 are still classified... I can't imagine information on other modern armor is readily available either.

 

[Drakkith]

From: http://en.wikipedia.org/wiki/Sloped_armour

However, the latest main battle tanks use perforated and composite armour, which attempts to deform and abrade a penetrator rather than deflecting it, as deflecting a long rod penatrator is so difficult. These tanks have a more blocky appearance. Examples include the Leopard 2 and M1 Abrams. An exception is the Israeli Merkava.

The relevance of sloped armour has further diminished due to modern top attack weapons and the increase of urban warfare in which the roof of AFVs is often attacked from high buildings.