# Need answers on tubular structures

1. Sep 21, 2009

### buf006

Ok so I have been looking over the internet on reading material on structures of tube. From experience I know this happens with items like straws (see illustration below). Is there an actual name of the phenomenon that happens (maybe a few formulas)

If you don't understand the picture from just the drawings feel free to ask and i will try to clarify as much as I can.

2. Sep 21, 2009

### buf006

thanks for the move. i really didn't know where to ask this question.

3. Sep 21, 2009

### ank_gl

Buckling

4. Sep 22, 2009

### buf006

before the buckle. i want to know what it is called when it starts to bend and before it buckles.

5. Sep 22, 2009

### nvn

I agree that ank_gl has given the correct answer to post 1. Regarding your question in post 4,
when the tube starts to bend but before it buckles, this is called bending deflection.

6. Sep 22, 2009

### buf006

O ya. i know its buckling when the tubes buckles (haha). With bending deflection isn't that only when a force is applied perpendicularly to the tube and not when applied against the tube?

7. Sep 22, 2009

### ank_gl

I would suggest you to read a chapter about buckling from some good book, or simply http://en.wikipedia.org/wiki/Buckling

Just for a start, compressive failure is way more complex than tensile failure.

8. Sep 22, 2009

### nvn

No, bending deflection occurs when bending moment is applied to the tube, regardless of which
force caused the bending moment.

9. Sep 23, 2009

### ank_gl

& the bending moment can occur due to load eccentricity, material inhomogeneity etc. Compressive failure study is more experimental than theoretical.

10. Sep 23, 2009

### Mech_Engineer

The phenomenon is definitely buckling (a.k.a. elastic instability). You should read about it in a strength of materials textbook. There is a pretty good summary of it here: http://en.wikipedia.org/wiki/Buckling