HEAT liner material

[jwduquette1]

Since we are shooting off precious metals -- does anyone know the bulk sound speed of platinum? It’s ductile, very high specific gravity, FCC lattice.

[arcweasel]

Since we are shooting off precious metals -- does anyone know the bulk sound speed of platinum? It’s ductile, very high specific gravity, FCC lattice.

 

I don't have platinum specifically (silver is about 3650mps) but you could estimate it from this:

 

In a solid rod (with thickness much smaller than the wavelength) the speed of sound is given by:

 

C= sqrt(E/r)

 

where

E is Young's modulus

r (rho) is density

 

In a solid with lateral dimensions much larger than the wavelength, the sound velocity is higher. It is found by replacing Young's

modulus with the plane wave modulus, which can be expressed in terms of the Young's modulus and Poisson's ratio(v) as:

M = E*(1-v)/(1-v-2v^2)

 

Regards,

 

Jay

[jwduquette1]

I don't have platinum specifically (silver is about 3650mps) but you could estimate it from this:

 

In a solid rod (with thickness much smaller than the wavelength) the speed of sound is given by:

 

C= sqrt(E/r)

 

where

E is Young's modulus

r (rho) is density

 

In a solid with lateral dimensions much larger than the wavelength, the sound velocity is higher. It is found by replacing Young's

modulus with the plane wave modulus, which can be expressed in terms of the Young's modulus and Poisson's ratio(v) as:

M = E*(1-v)/(1-v-2v^2)

 

Regards,

 

Jay

 

Thnx Jay -- I get about 2790m/s using your first equation. I suppose this isnt very exciting relative to C for gold or copper.

[gewing]

That's a very interesting question. I suppose it would be desirable to combine a copper liner with some other type of nonferrous metal liner that is pyrophoric. Let the copper do the penetration work and than the incendiary element like magnesium, uranium or aluminum enhances the behind armor effects. However, any sort of discontinuity between a liner containing two discrete metal cones -- even very very small gaps -- will severally degrade penetration performance. I suppose it would boil down to someone developing a cheap process that eliminates any sort of discontinuity between the two perfectly mated cones.

 

 

if, as JWB suggests, the metals would separate, it might potentially have advantages.

 

avoiding discontinuity is the easy part, I THINK! I could very easily be wrong, but...

 

 

The basic material the cone is to be made from would be clad, like a coin. The cone itself would then be formed by a die in a multi ton press.

 

Does anyone have any links to sites with diagrams of the actual formation of EFP or shaped charges?

 

My understanding is that if the cone were cut into multiple pieces then re-assembled before detonation, the separate pieces would still be separate if the jet was captured in a water tank for instance.

 

Is the tip of the jet formed from the tip of the cone, more or less? or is it from the lips of the cone?

 

I am also curious about the pattern of the shockwaves around the charge...

 

 

Depending on how it actually works, the composition of the disc the cone would be formed from could be varied.

[JWB]

Here are some excellent pics>

 

http://www.llnl.gov/str/Baum.html

[jwduquette1]

if, as JWB suggests, the metals would separate, it might potentially have advantages.

 

avoiding discontinuity is the easy part, I THINK! I could very easily be wrong, but...

The basic material the cone is to be made from would be clad, like a coin. The cone itself would then be formed by a die in a multi ton press.

 

Does anyone have any links to sites with diagrams of the actual formation of EFP or shaped charges?

 

You mean the manufacturing process for constructing a cone -- or jet formation following detonation?

[jwduquette1]

Thnx Jay -- I get about 2790m/s using your first equation. I suppose this isnt very exciting relative to C for gold or copper.

 

Came across a reference on Wikipedia indicating bulk sound velocity of Platinum is ~2800m/s.

[arcweasel]

Came across a reference on Wikipedia indicating bulk sound velocity of Platinum is ~2800m/s.

 

Nice when a formula actually has some relation to reality. Assuming that the wikipedia number is not just from the same equation

[jwduquette1]

Nice when a formula actually has some relation to reality. Assuming that the wikipedia number is not just from the same equation

 

it probably is -- although it said something about "C in thin rods". whether that is supposed to imply it was measured experimentally in thin rods, who knows. one never knows what to make of wikipedia, but was the only direct google hit I could get on the subject.

 

more sort of a gee-wiz thing as I don't think anyone is wasting there platinum in shaped charges beyond experimental work.

[gewing]

You mean the manufacturing process for constructing a cone -- or jet formation following detonation?

 

 

 

jet formation.

 

Also the slug formation of an EFP. I seem to recall that a conventional shaped charge also forms a slower slug, but...

 

 

 

I am also interested in what the blast patterns/effects in front of the cone are, for example what would happen if the ballistic windshield in front of the cone was made of either a pre stressed for fragmentation metal or of a polymer with embedded tungsten fragments?

[jwduquette1]

Scanned from some work by Manfred Held.

 

Apparently my dogs have been using my scanner again. Black fur everywhere.

Edited November 23, 2007 by jwduquette1