Book recommendation (Structures under impact) 2

[vtmike]

Hi,

Can anyone suggest some books for structures under shock and impact? (for example designing a steel plate impacted by a bullet.....which text should i use to learn about designing such structures?)

Thanks,
Mike

 

[ShaggyPE]

IMO, that is the question of the ages. I too am curious about such things. I have done a brief amount of searching and have found very little regarding impact, specifically stresses caused by impact. I believe this is because it is an extremely complex phenomena that is dependent on the specific design situation. I also believe it is necessary, cheaper, easier... to do testing with representative models and prototypes and full up designs... think automotive crash tests.

About the only direction I can give you is the textbook Fundamentals of Machine Component Design by Juvinall and Marshek. It has a 25 page chapter on impact. There are also a couple of papers referenced by this chapter:
Rinehart, John S., and John Pearson, Behavior of Metals under Impulsive Loads, The American Society for Metals, Cleveland, 1954.
-and-
Vigness, Irwin, and W.P. Welch,Shock and Impact Considerations in Design, in ASME Handbook: Metals Engineering--Design, 2nd ed., Oscar J. Horger (ed.), McGraw-Hill, New York, 1965

Let me know if any of these sources help you. I have never needed to design for impact, but am interested in the topic.
Good Luck.

-Dustin
Professional Engineer
Certified SolidWorks Professional

 

[ShaggyPE]

Also,
Here are some good links:

http://www.jw-stumpel.nl/bounce.html

http://www.brushwellman.com/alloy/tech_lit/julycom7_99.pdf

-Dustin
Professional Engineer
Certified SolidWorks Professional

 

[vtmike]

Thanks for the references. Will try to dig them out and let you know if they were useful....i have done some work on crashworthy seats but this problem is different....the bullet hitting a metal plate must be very hard to design analytically..i guess one solution would be an FEA analysis and validate the results with tests. Even a FEA simulation would be very challenging atleast for me.

Regards,
Mike

 

[hendersdc]

I have done some modeling and testing of a domed plastic lens under impact and have found this formula to be close, but conservative.

d(impact)/d(static) = sigma(impact)/sigma(static) = SQRT((v^2)/(g*d(static)))

Where:
d(impact) = deformation under impact load
d(static) = deformation under static load
sigma(impact) = stress under impact load
sigma(static) = stress under static load
v = velocity of impact
g = gravity

This equation applies to a horizontal impact as in your bullet/ plate case. d(static) and sigma(static) are the deformation and stress the weight of the moving body would produce if applied as a static load in the direction of the velocity of impact.

This equation assumes no kinetic energy is disipated by the impact which is untrue and adds to the conservative nature of the equation.

This can be found in Roark's Formulas for Stress and Strain.

 

[hendersdc]

The formula above only applies to elastic deformation. There should be quite a bit of plastic deformation in your bullet/plate scenario.

 

[GBor]

You may want to check with these guys:

http://www.materials-sciences.com/dyna-factsheet.pdf

They have written a subroutine for composite materials for LS-DYNA, and undoubtedly have the analytical basis for their impact solution. LS-DYNA publications probably explain a lot as well.

 

[GregLocock]

Check out the battleships people, Nathan Okun in particular. There is a wealth of information on the penetration (or lack thereof) of steel plates by various projectiles. Nathan has written some programs (Facehard etc) that seem quite reliable when dealing with oblique as well as normal penetration.

http://www.navweaps.com/index_nathan/index_nathan.htm

Cheers

Greg Locock

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

 

[GBor]

Greg,

I worked in the military marine industry for several years. I didn't do much in the way of armor piercing calculations, but I also never saw this website...good one!

 

[vtmike]

thnks for all the help!

 

[IRstuff]

Greg,

Lots of good stuff! Do you know if there's been any correlation of the programs against current RHA steel or titanium armors?

TTFN

FAQ731-376

 

[GregLocock]

I suggest you contact Nathan directly, he's a very knowledgeable guy. To be honest once you get much past WW1 I lose interest, so I don't even try and follow the modern stuff.

It wouldn't surprise me if

http://www.tank-net.org/

had some good resources on more modern armor.




Cheers

Greg Locock

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