Strength/Flexibility Relative to Structural Shape

[randy64]

First of all, not an engineer. I'm a designer.

I have a rectangular steel bar, .75" x 3" with a length of 24". The engineer tells me when in use (as a type of strap clamp) there is bending.

Question: If that rectangular bar is replaced with a similar sized bar, but with a perpendicular member included (making it a T, C or L-shaped bar) would that help prevent the bending?

Thanks!

 

[phamENG]

I think you may be conflating bending and deflection.

Bending happens to all beams - it's just the development of flexural stresses. Not a bad thing, as long as those stresses don't exceed the allowable limits for whatever you're designing.

Deflection is the amount of movement (and what most non-engineers think of when they here 'bending'). Deflection can take different forms depending on the type of material. For steel, you have a large range of elastic deformation - it will deflect, but return to its original shape when the load is removed, and plastic deformation - the material has permanently deformed and will not return to its original shape without applying an opposite force to bend it back (which then gets you into strain hardening, cold working, and a range of other material issues.)

Increasing the depth by using a deeper section (as you described) will, all else being equal, reduce the bending stress and reduce the deflection. Be careful, though: unstiffened elements in compression can be prone to local instability failures that will render them ineffective.

 

[desertfox]

Hi randy64
Take an ordinary 12” rule hold in both hands one at each end and bend the rule with both hands about the thin section of the rule and see how easy it bends, now turn the rule in your hands so that the scales can be read and try and bend it about that axis and see how stiff it is against bending. So if you have a rectangular section and place a section on top of it like making it a tee section then it should be stiffer.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[SWComposites]

randy - I agree with the posts above. Also, you should get with "the engineer" and together determine the appropriate shape for the part that meets all of the requirements.