What happened to the projectile in Hypervelocity Impact tests?

Question

I recently saw a tweet about Hypervelocity Impact Sample and someone ask how is it possible to shoot a projectile at that speed and what happened to the used projectile when hitting the shield.

I found that it was probably shooted by a Two Stage Light Gas Guns but I didn't found anything about the projectile.

I only found this:

They got their name because hypervelocity impact produces local pressures in the target and projectile that greatly exceed the material strength of these materials, the material behaves as if it has no strength, i.e., like a fluid, or hydrodynamic behavior

Handbook for Designing MMOD Protection

What happened to the projectile ?

Does the projectile melt with the shield ? At this speed, does the projectile melt before hiting the shield ?

EDIT: deletion of the last question, test done in vacuum.

Answer 1

When the collision velocity of a projectile is fast and the target hard and unyielding the impact produces forces that are greater than the compressive yield strength of the projectile and target.

So the projectile will collapse onto itself in plastic deformation while penetrating into a deepening crater in the target while converting its huge kinetic energy into heat.

This heat will liquify the projectile and crater into molten metal which can produce a cone of ejected red hot metal reflecting back and leaving traces of burn lines radiating out.

The impact force,F , must be such that:

$$ \frac{F}{A_{projectile}} = m\frac{\delta v}{\delta t}/A= m\frac{v_{projectile}}{ \text{very small t}}/A> F_{\text{projectile yield strength}} $$

This is the first rough explanation. Weird things happen in a fast collision. Extensive tests have been done by artillery and shell manufacturers and designers of armory shields. Albeit the data is proprietary trade secret.

Answer 2

In some tests, the Livermore crew fired their projectiles into piles of sandbags, as documented here: https://crgis.ndc.nasa.gov/crgis/images/8/85/TRP00308.pdf

I seem to recall reading that in later tests, they were firing into a bore shaft in a hill downrange, and that the bore was filled with carpet scrap (that variously compressed, shredded and/or melted), but I can't find any photos of that.

Answer 3

The projectile typically melts or vaporizes during hyper velocity impact due to the energy of impact being dissipated as heat during plastic deformation. The physics is quite involved.