Cracked SAPI plates and edge effects?

[EchoFiveMike]

SAPI plates are prone to cracking of the ceramic (boron carbide) component. This is bonded in some fashion to the backing which I presume is of an aramid fiber perhaps combined with Ti.

 

Does this cracking significantly reduce the effectiveness of the plate?

 

As I understand it, the ceramic is there to break up the projo, as well as distribute the resulting fragments over a greater area of backing material. With no confinment in any case, I don't see how the crack significantly reduces this effect.

 

Thoughts? S/F.....Ken M

[Simon Tan]

Cracks act as stress points and increase the likeihood of structural failure, resulting in reduced ab aility to absorb ballistic impact. A lot of the energy of the bullet is absorbed in the fracturing of the boron carbide matrix which then allows the aramid backing to backstop any leakage. The plates are too thin to really employ any of the dynamic shearing effects used in composite armour arrays like on tanks.

 

This is one reason for looking at polyethylene now coming through apart from weight.

 

Simon