RE: [OT]Stupid question about sloped armour

That phenomenon is known as "spall" and most armoured vehicles are
equipped with spall liners to catch such fragments.  I believe that this
a big problem in APC's with aluminum armor vs. steel armor in that
aluminum spalls worse than steel and so is a big debate in the weight
savings vs. armor protection arena.

--Binhan

> -----Original Message-----
> From: Katie Lauren Lucas [mailto:katie@fysh.org]
> Sent: Wednesday, May 01, 2002 1:51 AM
> To: gzg-l@csua.berkeley.edu
> Subject: Re: [OT]Stupid question about sloped armour
> 
> 
> Quoting Edward Lipsett <translation@intercomltd.com>:
> 
> > If the only benefit were the extra thickness provided by the sloped
> > cross-section, then ceramic armor wouldn't have much to offer over a
> > lump of
> > steel, would it?
> 
> Ceramic armour fragments. You can embed a metal mesh in the 
> ceramic to retain 
> the fragments - because ceramic fractures along fractal 
> surfaces, retaining the 
> large fragments will effectively lock in the smaller 
> fragments. This is the 
> basis behind "Chobham" armour, I believe.
> 
> So a lot of the shell's energy is spent in making cracks. Now 
> obviously, this 
> isn't good long-term (probably don't want to get hit again in 
> the same place), 
> but in the short-term, the energy is absorbed.
> 
> Steel armour bends (which absorbs energy), but bends enough 
> to transmit energy 
> to the interior surface, which is flaked off at high speed 
> into the tank 
> interior...[1] this is because metal deforms and then 
> delaminates fairly easily 
> along crystal boundaries.
> 
> 
> {Annoyingly we discover ceramic composite armour doesn't seem 
> to be covered in 
> the rules for Robot Wars. Mind you, the powerplant we've been 
> looking at using 
> isn't in there either...}
> 
> 
> [1] Why isn't the tank interior coated with something to retard these?
> 
> ______________________________________________________________
> _________________
>	Katie Lauren Lucas, Consultant Software Engineer, 
> Parasol Solutions
> katie@fysh.org katie.lucas@parasolsolutions.com 
> http://www.parasolsolutions.com
>