How to set up bolt joints properly


#1

Hello,

I am relatively new at using FEM software, and I have doubts regarding how to set the contacts between two solids that are joint by bolts. Here you can see the model (v7.1):

https://www.simscale.com/projects/jmateo/gamma_shield_support_v6/

I have done it by myself but not sure it is correct.

  • Is it valid to create one contact constraint for all individual bolts (as I did, one for bolt-cylinder and other for bolt-frame) or I need to create an individual constraint for each one

  • Also do I need to split the exterior surface of the bolt so I can select only the side which is implicated in each contact?

  • About the mesh, is it over-meshed? I wonder If a coarser mesh would be enough

  • Can you please check the whole model to find incoherences? (for example, it seems weird to me the way the supports are set up, as I need to specify the point by coordinates)

Thank you for the help
Regards,
Javier


#2

Hi @jmateo and thanks for reaching out to us!

Let me tag the FEA experts - the @PowerUsers_FEA - here. I am sure they can help you out with your issue.

All the best!

Jousef


#3

Thanks a lot!

Let see If someone has any tips here


#4

Hi @jmateo!

Let me just give you some small tips on your questions as nobody could answer so far :slight_smile:

I would recommend creating a master-slave assignment for each individual contact!

Splitting surfaces makes sense especially when you need to define a separate boundary condition.

Looks like a good mesh to me. I would start with a coarse mesh always and do a convergence study to see the effect on the results.

Looks good to me so far. You need to define the coordinates as you are using the remote displacement boundary condition. You could also work with a fixed support or a displacement boundary condition setting the lower part encastré. My colleague @rszoeke created a nice post for this issue a while ago: Remote Displacement BC.

Best,

Jousef


#5

Ok, thank you for the useful response !

I have just one more question

If you see this picture


You can see I forgot to make some surface on the CAD imported model for selecting the master entity, for making the contact with the wire

Do I need to create a surface in the CAD model always (with the elliptical shape from the cable, in this case), or it is fine If I leave it like that?


#6

Hi @jmateo!

You can leave it as it is and do not have to define a separate region with elliptical shape just to create a master surface.

Let me know how things go!

Jousef


#7

Great, thank you again !

Well, the results are negative. It seems that this joint setup is not strong enough. However, I did the bolt checking following Eurocode and results were quite safety. Just in case anyone wants to take a look :slight_smile: here it is:

https://www.simscale.com/projects/jmateo/gamma_shield_support_v6/

(se 7.1 version)