Quote:
Originally Posted by Chris is me
How much is "much"?
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The moment of intertia of the cross section is directly related to it's stiffness.
If you google, you'll see for a rectangle, the moment of inertia is 1/12bh^3 (base and height). Base being the side parallel to the axis the beam is being bent around.
So, a 5" tall .050" thick plate has an I = 1/12(5in)(.050in)^3 ~ 5x10^-5.
The same beam with two 1" flanges is that I plus the I of the two flanges. I = 1/12(.050)(1)^3= .004
So the beam with the two flanges has a total I of .004+.004+5x10^-5 ~.084.
.084 / (5x10^-5) ~150:1.
Even if I made a mistake in the math somewhere, this demonstrates the difference flanges make in design. I could go on for pages elaborating this, but it'd better to google and look yourself (key terms being beam, cross section, moment of inertia, etc...). You'll also then understand why I-beams are shaped the way they are.
To ANY Robowrangler students reading this thread:
If any of you ask me about the game hint, at any time, you will be assigned 4 hours of shop cleaning duty during week 1. No exceptions. - JVN [more] 
22-06-2010, 01:06
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