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Unread 18-03-2010, 01:05
Ian Curtis Ian Curtis is offline
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Re: pic: 2791's Brand New Arm

Quote:
Originally Posted by Andrew Schreiber View Post
Just a personal off topic request, could someone who CAN explain this well (or at least point me in the direction of the relevant equations) elaborate on this. I am an ignorant CS major but I am REALLY curious.

Sorry for threadjacking Chris.
Wikipedia does a good job with the math under this heading: "Second moment of area for various cross sections"

I tried writing more in depth descriptions, but I can't get something down that uses the math.

In physical terms, think of it like holding 2791's arm with one end in a vice. If you were to press down on in, it would take a lot of effort to bend it. However, to bend it away/towards you would take significantly less, right? It seems from Chris's post that it was in this away/towards bend that the air failed. It turns out that adding just a little material in the plane that bending is occurring gives you much more strength.

TL;DR 2791 built an arm well prepared for tension/compression, but not strong enough for bending.

P.S. This all assumes I read Chris's original post correctly. By bowing, you meant that head on the arm used to look like || and now looks like ()... right?
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