Determine Cross Sectional Area of a truss

[ktaliaf1]

I am recently new to Ansys. I have a problem where i have to determine the minimum cross section area of the circular element to prevent buckling for the truss with the minimum weight. There is an allowable stress of 20 ksi and a Young s Modulus of 200 GPa. If anyone could help me with the problem i would greatly appreciate it. I attached a photo of the truss. Thank you

 

[GeorgeEllwood]

Hi ktaliaf1,
You might find this tutorial helpful to begin with:

http://www.mece.ualberta.ca/tutorials/ansys/BT/Truss/Truss.html

It shows you how to build simple truss models in ANSYS and you should be able to use it as a guide to help create your own geometry.
In order to follow the tutorial one difference you might have is the element type LINK1 used in the example is no longer supported depending on which version of ANSYS you're using, I think it's been replaced by LINK180 in later versions.
When creating your own model you'll need to include some information about the cross section of the beam. In order to do this I think you'll need to use a beam188 element or similar and then give it the cross section by using SECTYPE, 1, BEAM, CSOLID command. It's best to look these up in the help to get an understanding of how they work and what information you need to provide.
Once you've got your model behaving as you expect you should be able to perform a sensitivity study changing the cross sectional area until you get to the allowable stress.
There are lots of useful well explained tutorials here:

http://www.mece.ualberta.ca/tutorials/ansys/index.html

Cheers
George