Max Von Mises Stress Calculation for Pipe Bend

[dfitz1000]

Hi, I'm trying to calculate the max (von Mises) stress in a 90^o pipe bend. Now I know (I think) how to do it for a straight pipe, but can anyone point me in the right direction as to where I can find this analysis for a pipe bend?

Thanks in advance.

 

[minger]

Given what loads?

 

[dfitz1000]

Given what loads?

The internal pressure is around 4 bar.

 

[minger]

Have you taken a look for any analytical/empirical solutions such as in the Roark handbook for stress and strain?

I doubt there is a solution for your exact pipe bend, but I know there are solutions for simple shells of revolution under internal pressure. Perhaps you can adjust the solution for the bend.

 

[dfitz1000]

That's pretty much what I'm looking for minger. Roark's handbook you say, do you know any other books with a similar analysis? Thanks for your help so far.

 

[Studiot]

Don't forget that if your pipe fitting is under pressure, presumabably there is also fluid flowing. This exerts a thrust on the pipeline, which resists in bending, unless there is a suitably placed thrust block, in which case there is a direct force on the fitting.

Look in any standard hydraulics or fluids testbook for thrust block design.

Obviously it will make a difference whether the pipe is horizontal or vertical so the question 'what loads' remains open.

 

[dfitz1000]

Well, it's just a theoretical question. I need to find the maximum theoretical stress in the 90^o pipe bend under 4 bar internal pressure. It's a static analysis I'm doing so there's no need to consider thrust or anything like that. I do appreciate your reply though.

 

[Studiot]

In my opinion, forces from the flow exerted on the pipes are too often ignored or not taught.

I have seen really serious consequences ensue as a result of inadequate thrust block provision.

I have also seen serious damage ensue from neglect of bouyancy, self weight or support forces in soft goround.

 

[dfitz1000]

In my opinion, forces from the flow exerted on the pipes are too often ignored or not taught.

I have seen really serious consequences ensue as a result of inadequate thrust block provision.

I have also seen serious damage ensue from neglect of bouyancy, self weight or support forces in soft goround.

I don't doubt what you're saying but I just need to calculate the max von Mises stress in the bend. Just assume there is no flow.