SimScale CAE Forum

Pressure Vessel Stress Analysis at Junction


#1

I wish to analyze the stresses when a cylindrical shell is welded to a hemispherical head. Cylinder is 1200 mm ID x 12 mm thk, MOC is carbon steel. Internal pressure is 29 bar g.
Hemispherical head is 6 mm thk. How can we set it up in Simscale?


#2

Hi @sfaiz!

We can do that using a pressure BC from the inside and by using the advantages of symmetry which I assume are existent in your case. We would have to see if there is a way to model your material. Please share your project with us in form of a link so that we can give you further suggestions.

Best,

Jousef


#3

Thanks for replying. Please find attached a simple 3D sketch in Onshape. If you want me to add more details, let me know.

https://cad.onshape.com/documents/562a6421ab2d30af415a4b38/w/56e225735d2a29c6391badc9/e/a2e965530a148257f39fea11


#4

Hi @sfaiz!

You can use SimScale’s integrated Onshape import tool and then share the SimScale project link with us (if it is non existent at this point) :slight_smile:

This project from our PowerUser @ggiraldo might be useful for you: Plastic Analysis of a Pressure Vessel

Cheers!

Jousef


#5

Hi @sfaiz,

And thanks @jousefm for the mention.

I took a look at your model. I suggest you to include some features in your model before yo try to simulate:

  • Model the welding bead. so you don’t have those sharp corners which will artificially concentrate stress and are not real.
  • The way the vessel is supported is important, so model the legs or at least create the faces where they would connect.
  • You can make use of symmetry simplification (as suggested by Jousef) if the only load you will analyse is internal pressure. You can for example use only one eight of the geometry (if you do this I you can skip the support modelling part).
  • For the material modelling, start with elastic material to make sure your case is well defined and mesh is fine enough, then try and include a plasticity model, you can start copying the one on my project, as linked by Jousef.

Feel free to make further questions, we are here to help.


#6

Hi @sfaiz

As you shared your project with me, I copied it and made a simple simulation, to show you how it should be setup:

https://www.simscale.com/projects/ggiraldo/discontinuity_analysis/

Here you can see a picture of the region of interest:

I have to say that this simulation is very simple and not satisfactory. I think you should focus on the discontinuity region and make an axy-symmetrical model. Also mesh should be much finer.


#7

Ok. Thanks a lot.