Hi

Don't know of a free program to do the torsion analysis of tubes.  Enercalc (www.enercalc.com) will do torsion of wide flanges, but not tubes for some reason, and they have a free demo.

AISC has a design guide and software package for sale on torsion design.  The guide is very good, don't know anything about the software.

Here are the links to both:

http://www.aisc.org/template.cfm/template.cfm?template=/Ecommerce/ProductDisplay.cfm&ProductID=125

http://www.aisc.org/Template.cfm?Section=HOME&template=/Ecommerce/ProductDisplay.cfm&ProductID=201


Also, I am sure Roark's Formulas or any good Mechanics of Solids text would have the equations for what you are looking for.  Without knowing more about your problem, I can't give you the exact equation.

Perhaps, if you tell us what you want specifically (twist angle, stress, etc), the end conditions of the tube (free to twist or restrained), and the load configuration (single point twist at middle, uniform twist along length, etc), then I could give you the coorect equation.

Hope this helps you out some.

I would suggest trying it on your own instead of using a free program.

Try the tables at the back of Blodgett - Design of Welded Structures

tg

shear stress=T/(2tA)
T=torque
A=area enclosed by the walls of midsurfaces
A=5.75x5.75=33.0625   in^2
t=0.25"
fsi

Yes there is a freeware/shareware program called Engineering Power Tools go to www.pwr-tools.com    ;
E-MAIL : support@pwr-tools.com
There you can find a number of tools but there is a very good progam that lets you calculate the second moment of area and then the torsion of a 'shaft', providing you know the second moment you can of course calculate any shape in torsion.
Br
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