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# Tube Deflection

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## Tube Deflection

(OP)
I have a tube that is being forced against a fixed top face (see attached for details) and I am trying to calculate the perpendicular deflection when the force is applied.

I do not have a clue where to start, any pointers would be very helpful.

### RE: Tube Deflection

Theoretically, with no load in the direction of the deflection you are looking for, there should be no deflection.

However, in the real world, considering buckling of the column due to inherent instabilities and eccentricities in the system, the pipe column will have a P-Delta deflection due to the moment of the force P times the eccentricity of the system.

Roark might have something on this, but Timoshenko and Gere would be the better option in my opinion.

Mike McCann
MMC Engineering
http://mmcengineering.tripod.com

### RE: Tube Deflection

No telling what will happen laterally, because the pipe will crush.

One clue as to where to start...find an appropriate forum for your question. This has nothing to do with earthworks and grading.

If you are really a mechanical engineer, this should be a simple problem. Another thing...don't mix unit systems. Millimetres and tons don't belong together.

### RE: Tube Deflection

I may have jumped to an incorrect conclusion about the pipe crushing...if the P110 represent 110 ksi yield steel. That is about 750 MPa, while the 120 ton force would amount to a little over 600 MPa on the tube. A lot, and any eccentricity would bring buckling into play.

### RE: Tube Deflection

(OP)
Thanks, I had not realised I have posted this in such a foolish place, it was my first post so it appears that this didn't really go to plan! I will give it another go on another area. Thanks for your feedback anyway.

### RE: Tube Deflection

You got an inverted column, so check strength of material book for formulae on columns. One such formula is provided for a column with a fixed end and a load applied on the other end.

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