Ballistic Impact Analysis
Ballistic Impact Analysis
(OP)
I have a problem where I need to predict if a chunk of steel travelling relatively fast will fracture a steel plate. The specifics are a chunk of steel munitions casing impacting an A36 plate as a result of the munition exploding. I can estimate the particle size and initial velocity fairly well. A literature review shows that the modern method of doing this is with FEA.
Is there a free program that I can use to to analyze this? Would the Impact program on sourceforge work?
Is there a method of computing this by hand? References?
Thanks.
Is there a free program that I can use to to analyze this? Would the Impact program on sourceforge work?
Is there a method of computing this by hand? References?
Thanks.





RE: Ballistic Impact Analysis
Hope this helps.
GBor
RE: Ballistic Impact Analysis
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Ballistic Impact Analysis
I think we might outsource this problem. It's getting a little (or a lot) beyond my experience level.
I used ANSYS alot in grad school for static analysis, never dynamic, and my company now only has ANSYS CFX, I would think I'd need ANSYS LS-Dyna for this.
Any references for hand analysis of dynamic impact fracture?
RE: Ballistic Impact Analysis
TOP
CSWP, BSSE
www.engtran.com www.niswug.org
"Node news is good news."
RE: Ballistic Impact Analysis
I thought Calculix had some level of contact, but perhaps I am wrong. Another reason to look at AMPS with their "contact: all" capability...very impressive.
RE: Ballistic Impact Analysis
a) bending
b) gross shear
c) membrane action
d) local compression
The lowest value of all of the 4 above would be the governing mode of failure. All of the above can be done by hand, although probably with less accuracy than FEA methods.
RE: Ballistic Impact Analysis
So if your fragment size is significant then there is a lot you can do using battleship technology and hand analysis.
If nothing else a google on NATHAN OKUN will give you some good background reading.
Cheers
Greg Locock
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RE: Ballistic Impact Analysis
TOP
CSWP, BSSE
www.engtran.com www.niswug.org
"Node news is good news."
RE: Ballistic Impact Analysis
It looks like Nathan Okun has too much time on his hands. What a great resource. I haven't even come close to reading all of his pages, but it appears that most of his information deals with penetration of the armor plate. I don't think I actually have a penetration, more of a fracture due to impact. The Army has some good data on projectile penetration also. The one with the coolest name is the "Thor" equation.
We've ended up hiring a company that's going to do a parametric study with LS-Dyna. We'll see what we come up with. Thanks for the input.
RE: Ballistic Impact Analysis
I'm trying to define a failure criteria for my fracture. It's pretty difficult because of the strain rate and other effects. Our consultant said he's going to use a piecewise elasto plastic model. Ever used one of those? Any references for me to brush up on it?
I've looked into the Johnson-Cook model, but my consultant said that's outdated. The Johnson-Cook model takes into account hydrostatic stress, strain rate, and temperature. My consultant says that temperature doesn't matter too much. I have pretty low temperatures, maybe 250F. Does anyone think that would make much difference?
Basically I need something that takes into account super high strain rates, and maybe temperature. Any suggestions? Any references?
Thanks
RE: Ballistic Impact Analysis
He would approach your problem needing the size of the chunk, the angle it approaches the plate and the thickness of the plate.
TOP
CSWP, BSSE
www.engtran.com www.niswug.org
"Node news is good news."
RE: Ballistic Impact Analysis