Tube/Bar Rigidity: Which Offers Most?

[SGT Steel]

Hey guys,

Long time lurker, first time poster! Here is my query...

I need to send a load weighing 10-12kg down two horizontal, parallel, cantilevered, grade 316 stainless steel tubes -- or bars -- each between 3-4 feet in length, 3/4" in diameter, and spaced 85mm apart. What I'd like to know is; in this specific application, would tubes, or bars, offer the most rigidity? If tubes, would a thicker or thinner wall thickness offer the most rigidity?

 

[PhanthomJay]

A tube with a thicker wall is more rigid than a tube of the same outside diameter and material but with a thinner wall, but the solid rod of the same outside diameter and material is more rigid than the thick walled tube. However, I don't consider a 4 foot long 3/4 inch diameter cantilevered rod as being very rigid. Might want to consider a larger diameter depending on your
application.

 

[tygerdawg]

How much deflection is allowable?
There are many beam analysis calculators on the web or in CAD modellers, or you can do the math yourself for the specific element's cross sectional profile. If you did this, perhaps you would find better solutions than tubular or solid circular cross sections that would solve your deflection issue. But would perhaps be more expensive or require more effort to mount.

It's all a series of trade offs.