penetration through plate

[LBTaurus]

K guys here's the deal

I have a high pressure testing system. We water test up to 5000 psi. We're designing a containment system for the tester (a steel box), so that if something goes wrong (an air bubble builds up pressure and destroys a tested item which then becomes a fairly dangerous projectile) we will have something that will prevent injury.

Assuming i know what the dimensions and material properties of my projectile are, and the maximum velocity with which it is moving.

How thick do my steel plates have to be in order to properly protect( ensure no penetration through them)

I understand that steel isn't the best way to design a containment system, unfortunately, this is the way it has to be done.

ANy help at all would be greatly appreciated

 

[TheTick]

I assume you know dimensions and material properties of projectile. This is correct. You assume we know dimensions and material properties of projectile. This is not correct.

 

[KENAT]

Could you treat it like you would armor penetration?

http://www.navweaps.com/index_tech/tech-033.htm

http://www.combinedfleet.com/formula.htm

http://www.eugeneleeslover.com/ARMOR-CHAPTER-XII-B.html

You can do google searches to get more hits, just beware that half the results are to do with 'world of warcraft' or similar computer/role playing games.


KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at

http://eng-tips.com/market.cfm?

 

[LBTaurus]

thanks Kenat, and Thetick

The projectile in question would be steel, and would most likely be a small quick connect hose fitting.

I am assuming that the smallest object will penetrate the most easily, and the hose fitting seems like it is also the mot likely thing in the system to fail.

However, since we've never actually had a failure, i really dont know what the worst case scenario is.

thanks for the help guys

 

[KENAT]

It's not just the size of the item, mass & shape I believe play a part.

You could have some fun experiments on this, firing pressure fittings at sheet steel!

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at

http://eng-tips.com/market.cfm?

 

[handleman]

I was gonna say, sounds like an ideal (fun) time for some edisonian methodology (hands-on trial and error)!

-handleman, CSWP (The new, easy test)

 

[LBTaurus]

well unfortunately i dont get to have that much fun...

experimentally it'll work, but when OSHA comes around and asks if my system is safe i cant really show a youtube video of me firing a modified potato cannon at a bunch of plates.

However, i do have access to cosmosworks, although a drop test on that only shows how my projectile deforms, not the plate.

ANsys was suggested to me by someone else, but I dont have those kinds of resources.

I agree that mass and shape play a part, as well as the angle. Im sure itll go through faster if an edge hits vs flat on. wouldnt it suffice to get a small cylindrical object's COM etc. ( similar to a quick connect, assume its indeformable and use it to get a worst case scenario?

Also.. since i do have cosmos, is there any way to get the max velocity and kinetic energy equations and turn the max impact load into a static load?
if i have a static load, the analysis is fairly easy

Keep em coming guys... appreciate the feedback

 

[handleman]

How big of an area do you need to protect around/guard? If:

1. You don't need a huge enclosure
2. You don't need to really move it much
3. You don't have to make more than one enclosure

it sounds like an ideal time to just throw steel at it and be done. 2" oughtta do it. If your place is anything like ours, your time costs more than the extra material beyond the "minimum".

-handleman, CSWP (The new, easy test)

 

[LBTaurus]

well, that's the tricky part. The max length of the testable mater is over 30 ft long. Our current tester is 36 ft long, so for the enclosure surrounding it, the difference between quarter inch and half inch thick steel is gonna be way more substantial than what I make here in a week.

The enclosures gonna be a box with a LONG phallic looking tube coming out of it. The box itself has to have rouchly 10X6X2 ft dimensions, and the tube, which has to be about a 5" ID, needs to be the appropriate thickness.

I need to find what is just enough

 

[KENAT]

OK, you may be able to find information on penetration of ammunition.

If you can find a type of bullet that has similar characteristics to the part you think is going to go flying you may be able to do a read across.

To do this you’d need to estimate the velocity of your fitting.

You could then do a sanity check using the equations I sent you, making very conservative assumptions.

I’m also not sure why OSHA wouldn’t accept something verified by testing. You’d have to have good experimental protocol etc., take safety into account and all that jazz but, I’d have thought something proven by appropriate testing is even better than just theory. That’s what we’d often do in Aerospace.


KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at

http://eng-tips.com/market.cfm?

 

[IRstuff]

There are mil specs for this (actually, there are mil specs for EVERYTHING).

See:
MIL-A-12560H(3)
MIL-A-46099C
MIL-A-46100D(I2)


Hopefully these are the right ones. Don't have time to open each one and check. Go to:

http://assist.daps.dla.mil/quicksearch/

and type armor for the search term in the title.

TTFN

FAQ731-376

 

[GregLocock]

Armour piercing capabilities of small arms shot are well known - your muzzle velocity will be subsonic so you would be well inside the performance of a typical gun, by a factor of three or more.

Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[KENAT]

I still think that if you can calculate your maximum impact velocity you may be able to find roughly what you need correlating to ammunition. Some hand guns or I think even some .22 rifles are subsonic. Most air guns certainly are.

If you can find a bullet with similar characteristics you may have a good starting point.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at

http://eng-tips.com/market.cfm?

 

[Pud]

Here's a list of muzzle energy for different calibres, grouped into energy bands. Page 2 onwards:

https://www.basc.org.uk/media/basc_-_energy_comparisons.pdf

If it's any use.

Harry

 

[eromlignod]

I think the only safe way to do this is by experimentation. Ten pages of calculations are going to be of little consolation to the family of the guy who took a shot to the skull. There are too many variables in such a setup to trust theory alone.

I have a feeling you're going to find that a surprisingly-thin steel plate is going to do the trick.

Don
Kansas City

 

[KENAT]

eromlignod, that's my feeling too.

You want to rig the experiment so the 'sharp edge' of the fitting if there is one is what impacts the plate if at all possible.

Use the calculations or comparison to ammunition to give you a starting point for thickness of sheet to test and go from there.

I will say this, pellets from airguns can be deflected/defeated by drinks cans and the likes. Now of course there may be an angular/deflection aspect but it still gives you some idea.

Depending on the size of the fitting you may find you don't even need solid steel, some kind of pierced panelling or 'grid' may be adequate.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at

http://eng-tips.com/market.cfm?

 

[griffengm]

LBT,
Seems to me that it might be cheaper and easier to set the subject in a huge open space and build protection around the observer like a bunker on a test range. How close does the operator/observer need to be and does he need to see directly or can observation be done by electronics?
Space may be cheaper than materials.

Griffy

 

[IRstuff]

MIL-A-12560H has a nice clean table for 0.30 cal AP down to about 1500 ft/s velocity, but you should be able to easily extrapolate the curve down to a few hundred ft/s.

TTFN

FAQ731-376

 

[rb1957]

the test machine is large (some 30'), but are the possible projectiles grouped together, maybe in a couple of places ?

what about using some kevlar jackets ? maybe making a flexible containment "tent", so that lots of the energy is absorbed by the tent.

 

[LBTaurus]

THanks for everything guys.

I'm detoured off this project for right now.. Now its VBA time..but im gonna be back in in full force soon...

All the input was great