Subject:
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Re: Physics/Materials geek question
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Newsgroups:
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lugnet.off-topic.geek
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Date:
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Sat, 5 Jan 2002 16:14:25 GMT
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Viewed:
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108 times
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In lugnet.off-topic.geek, Erik Olson writes:
> I know there is a difference between the yield strength of a material under
> load, and its strength under projectile impact.
>
> What I'm wondering -- and this is a little like our "going to Mars"
> questions -- is to estimate how much abuse will some typical tent fabrics
> take from small projectiles? For example, at what speed does a small rock
> kicked up by a truck puncture a canvas tent?
>
>
>
> If you need numbers, assume the rock is a 1 cubic cm pebble of 100 grams.
> Ignore the sharp corners, or make up "geometry constants" for different
> impact presentations. The truck fires rocks perpendicular to the tent
> surface (broadside) at speeds of 10-90mph. The tent costs no more than $300.
Did you want full FEA on that or will rough back of the hand range do?
Oh and more to the point What are those rocks made of to get that mass?
Lead works out as less than 20/cm3...
Actually the distance between tie points and overall stress that the
tent wall is at will make the most difference. Take for example a
worst case of honeycomb of 2cm cells allowing no slacking to take up
the force(MOI) and light-Tin plate would be minimum. Or we could
have more slack and distance to absorb impact say 4mm rubbercloth
at 1m (hexes again if you like or sq cells) and make sure you avoid
the 10cm nearest the wall.<grin>
But just a early morning had'only'single'cup'o'joe'so'far answer.
Best
DaveG
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Message has 1 Reply:
 | | Re: Physics/Materials geek question
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| In lugnet.off-topic.geek, David Goeb writes: OK, thanks, I will think about keeping slack in the tent when I start throwing rocks, that is easier to put in than tin plate. I'm sorry, I put a rubber eraser "rock" on a postal scale, rounded up the (...) (23 years ago, 5-Jan-02, to lugnet.off-topic.geek)
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Message is in Reply To:
| | Physics/Materials geek question
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| I know there is a difference between the yield strength of a material under load, and its strength under projectile impact. What I'm wondering -- and this is a little like our "going to Mars" questions -- is to estimate how much abuse will some (...) (23 years ago, 5-Jan-02, to lugnet.off-topic.geek)
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