Correct Penetration/Perforation Model?

[Ozen]

Been researching armor piercing mechanics but I can't seem to find a reliable model for hand calculations. What makes matters worse is I don't know the correct value for the design I am studying. Only 3 formulas gave me similar results: NAVY 1940's "Universal" Formula, Original F-Formula, and NAVY 1930s "Thompson F-Formula". The Lambert-Zukas formula yielded ~1/2 the penetration depths of those three. Wijk's Penetration Model yielded ~3/4th depth of the first three. And Pol's Model yielded ~5/6th the depth of the first three. So my results are scattered all over the place, and this is only the models that were in the ballpark, some gave back at ~0.1% of the depth computed.

How do I know which model is correct for my case? My case specifically is a small rifle bullet (0.224in diameter) of tungsten vs AR500 steel plate, velocity = 2800 ft/s, and mass = 1.1004774e-02 pounds. Length for the ones that need it is 0.924in.

The only model I haven't been able to figure out is "FURTHER RESULTS IN THE THEORY OF LONG ROD PENETRATION*" by A. Tate, which they use a long rod penetration model. What gets me is the Yp and Rt values for my case. Yp is the pressure at which the penetrator material acts like a liquid; and Rt is the pressure when the target material acts like a liquid.

I would just toss this into ANSYS AutoDyn but I can't afford the commercial version and the student version can't handle it (I tried..).

Making a couple test pieces isn't feasible since equipment needed to produce it is in the thousands.

Anyone have any ideas on what to do here?

 

[eljose79]

Dear fellow scientist,

I understand your frustration in finding a reliable model for hand calculations in armor piercing mechanics. It can be challenging to determine the correct value for the design you are studying, especially when different formulas are giving you varying results.

Firstly, I would recommend thoroughly reviewing the equations used in each of the formulas you have tested so far. Look for any discrepancies or assumptions made in the calculations that could be causing the discrepancies in results. This will help you eliminate any models that may not be applicable to your specific case.

Additionally, I would suggest reaching out to experts in the field of armor piercing mechanics and seeking their advice on which model may be most suitable for your case. They may be able to offer insights or suggest alternative models that you may not have considered before.

In regards to the "FURTHER RESULTS IN THE THEORY OF LONG ROD PENETRATION*" by A. Tate, I would recommend reaching out to the author directly or contacting a professional organization in the field to see if they can provide any guidance on determining the Yp and Rt values for your specific case.

If using ANSYS AutoDyn is not an option, you could also look into other simulation software that may be more affordable or have a student version available. Alternatively, you could consider collaborating with a colleague or university department that may have access to the necessary equipment and resources for testing.

I hope these suggestions are helpful in guiding you towards finding a suitable model for your case. Best of luck in your research.