Dynamic impact analysis on FEA

[jetskiPE]

I have the mass of a polar bear 599kg and its speed in the water = 3.13 m/sec. The bear impacts a vertical FE model (panel). Is there an equivalent force method to input into RISA? Thanks for any help!

 

[IRstuff]

Unless the polar bear is hitting the wall with his jetski, it will be a flesh on solid impact, so the impact time will be longer than with a solid on solid impact, which is known to be on the order of 0.1s.

I would think that one would start with that value, and then make some assumptions about what part of the polar bear actually impacts with the wall; can't imagine a polar bear that dumb, but...

So, now you have an area, a mass, and a deceleration.

TTFN

FAQ731-376

 

[SteveGregory]

You might want to send in the video of the polar bear on a jet ski testing one of your wall panels to America's Funniest Videos.

 

[ThomasH]

If you know the "deformation" of the bear it's just Newtons laws.

Basically, deceleration length = deformation and than you have deceleration / acceleration required to stop the bear. Than you know that acceleration * mass = Force.

And than its a static analysis. If you use the bears mass and multiply by 2 you get a conservative estimate for impact. You can probably find that in any decent dynamics book.

But I would like to see the polar bear on a jet ski.

Regards

Thomas

 

[rob768]

Thank god the bear is only 599 kg, and not 600. Can you imagine the impact of that..

 

[IRstuff]

This article discusses parameters of ballistic gels, which might be usable for calculations involving sody body tissues.

http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA481959

TTFN

FAQ731-376