EXPLOSIVELY FORMED PENETRATOR SIMULATION | EFP Shaped Charge Armour Piercing Simulation

An Explosively Formed Penetrator (EFP) is a type of shaped charge where the liner is formed into a high velocity slug, rather than a hyper velocity jet (which most shaped charges are). EFPs are infamous for their effectiveness as IEDs, which were used with great effect in the Iraq War.

The simulation presents a large, simple EFP, against 75mm of Rolled Homogenous Armour (RHA) at 800mm (4 Charge Diameters) of standoff. The EFP modelled is 200mm wide, 200mm deep, with a 8mm thick copper liner, and TNT explosive filler. The detonation point is at the back centre of the charge. In the simulation, the slug reaches a velocity of ~1500m/s. The formation and velocity of the EFP is in decent agreement with experimental data of similar EFP designs.

There are a variety of ways to simulate EFPs, with most modelling the liner as a Eulerian body, due to the large amounts of deformation. However, as the EFP slug takes a large distance to form and is relatively thin, the Eulerian domain would need to be very long and with a fine mesh, resulting in an exceptionally large amount of cells and a slow simulation.

Due to this, I chose to test if a Lagrangian liner would be suitable, with the results being surprisingly promising. The copper liner is made of 3D elements with a strain failure limit (this strain limit should be higher, however these excessively strained elements reduce the time increment and slow down the simulation so a compromise was made -this is why some of the material in the tail 'breaks' and converts to particles). A sheet body could be used for the liner as well, but this wouldn't be as visually impressive, especially in a crossection view.

[SYsimulations]

This was a test simulation I did before going on holiday but am keen to do another, higher fidelity EFP simulation against a more specific target. Does anyone have any target suggestions?

[chemistryofquestionablequa]

You can electroform copper onto the bottom of a monster can or spray paint can for a pretty effective small EFP that can penetrate light armor.

[huntsmanable]

This was the main type of IED my unit faced in Iraq 2007-2008. They were terrifying. We had one go off on a RG33L Mrap that we were told was 18" in diameter and it went straight through the engine block of the vehicle and through an over pass support column and kept going. thankfully it was aimed wrong so no one was badly hurt. We had another one go off but missed the vehicle add hit a house on the far side. I'm not kidding when i say you could kneel down and look through the hole it made in the house add see into 4 more houses because the projectile went through them like a cannonball

[resurgam_b]

That's neat! I didn't know there was differentiation between varieties of shaped charge penetrators, I figured they were all similar enough to be called EFPs.

[GeneralCalculus]

I was going to say that strongest form of EFP is hypothetical Casaba Howitzer, which uses hydrogen bomb to propel liner made of tungsten, but then I wasn't sure if it actually counts as "projectile" if tungsten turns into stream of plasma.

[SV]

In anti-ship missiles the shaped charge is this (efp) not heat. This is one of the main resons why battleships went out of use and not aircraft carriers as many think. The soviets had no carriers in the 50s and 60s, but built several missile types with efp warheads (500-1000kg). These would go through thickest battleship armour and would still cause massive destruction inside... unlike heat.

[andrewmalcolm]

I have a request that I thought of a while ago that I think would be interesting. What about a big 1800s cannon vs a modern tank? Obviously the cannon will have no chance but it'd be interesting to see what it'd actually do. I don't know enough to say what type, but those really big ones you often see on display in parks or on the coast. You could just about fit your leg down the barrel. A good example is in centennial park in Sydney, Australia.

[aaronclair]

This is very cool.

I've recently been wondering about EFP vs perforated spaced armor. It might be interesting to see this test repeated, with 10mm of RHA, an air gap, and then 65mm of RHA.

[AnthraciteGari]

it'd be interesting to see if a wave shaper could improve the performance of one of these, i see a lot of material getting blown away from the main projectils

[timtarbet]

Really like the addition of the explanation and the voice over. Very nice.

[nikitatarsov]

For the distance it fuses and minimise its shape & vulnerability (and creating lots of forces that can blind sensors) many modern active protection systems can be bypassed by range fused EFP's, granting them a niche even in the most modern battlefields.

Tbh i support that conflict got so complex and more and more the smarter competitor has an edge (if tools for benefitting are availabel).

[Nighthawke]

I recall a project that involved a 24" or 32" EFP assembly mounted on a quadrunner, complete with targeting and fire control. The project was called FIRE ANT. And it stung like one too.

[gdebouillon]

Who else is here after the last H4mas video?

[TheAllKnowNoble]

I’ve never heard of these. Great video, very informative

[RTankist]

I'd like to see a comparison between the M829A3 and a 3BM59 against the 800mm RHA

[ozzymarley]

I came here from a video about a man who lost his arms and legs to a EFP but the hot copper burned him in such a way he did not bleed and he survived... now he has 2 transplant arms! crazy world.

[Hookens]

Oh, so that's how TOW-2B works. Cool!

[prjndigo]

There's an effect upon the jet stacking up on the surface that Thunderf00t actually goes over in his video about water intrusion into the mini-sub being limited to about mach1 in spite of the immense pressure. So the jets aren't actually jets they're a plasmiated form of oobleck that then turns solid at the surface of contact resulting in a non-elastic application of a large proportion of the energy. The thing with these explosive charges is they're also velocity dependent for efficacy.

Take for example the 25mm high explosive shells fired by the M242 Bushmaster, they have a different cone angle from the 30mm shells fired by the chain gun used by the Apache helicopter because the M242 fires them at near-on 1150m/s whereas the ASP is designed for 825m/s and it does make a difference to have the correct cone angle.

Furthermore the animation you had in this video doesn't take into account the relatively rapid circulation out from the tip of the jet which works like a plasma lance.

[Tom_Quixote]

Would be interesting to see the exact same setup but different standoff ranges.

[PlutoTheSynth]

I love the voice over!! Great job!! :DD