generative design solution for structural joint

[merlin.bieling]

Hi,

I would like to generate a structural joint for our design. Its an underspanned Primary beam. In the place where the pressure girders meet with the primary beam there is an I Beam attached to the primary beam. I would like to create this connection using generative design.

The joint needs to be a loop that is perforated by the primary beam, but the generative design solution only offers a joint that is "open".

What corrections can I make to create this?

Is there a different solution to this than generating a tube as preserved geometry?

Thank you for your support,

Kind regards,

 

Merlin

here the joint is perforated by the primary beam creating a closed loop

the generative design solution with my settings only allows for an "open" loop which doesnt work in this structure

 

[John_Holtz]

Hi Merlin. Welcome to the Fusion forum.

Can you provide an image that shows what part from the first image you are trying to design? I am having problems correlating what is shown in the second image (the generative design result) with what is shown in the first image.

The next thing that we need to know is what are the loads and constraints in the first image. That controls what loads and constraints need to be applied to the generative design model.

The next thing (maybe the last thing? 🙂) is what has been defined in the generative model setup for the Preserved, Obstacle, and Starting shape geometry, if any. If I understand your part, it looks like there would be 5 preserves for the connections with the other bodies and one obstacle for the wide-flange beam (with the top flange partially cut away).

John

[merlin.bieling]

Hi John,

thanks for your reply, I have attached the file to this message, also heres another screenshot of the setup Ive created, the starting geometry is also what is supposed to be develpoed by generative design. 

We want the big horizontal tube to be able to take any momentum that might occur in this structural knot, thats why it has to wrap all around the tube. This doesnt seem to be possible without creating another preserved geometry on the other side of the tube. Do you know a trick to solve this?

Thank you,

Kind regards,

Merlin

[John_Holtz]

Hi Merlin,

I suspect that your analysis is missing a load that would help to create a complete ring around the "pipe". The gravity load that is applied only works on shape created by the generative design. What is missing from the analysis is the weight of all the beams (the obstacles in the model). I suggest that you apply a force to the the generative part that represents the weight of the beams acting on the joint piece.

In real life, there must be some type of contact between the "pipe" and the  joint. Is that correct? (I do not know what I am looking at in your model and what interacts with what, but I am sure that you know. 😉) You cannot create contact in generative design, but the contact that occurs creates either a force or constraint on the inside top of the joint. That should be added to the generative design analysis.

Let us know what you find out.

John

[merlin.bieling]

Hi John,

thank you for your reply, you understood my problem correctly, and with your help, I was able to create this workaround. I simulate contact by installing another preserve geometry on the top of the pipe, with a starting body and some extra forces this setup created the desired result in generative design. With some editing, I was able to correct the connection on the top of the tube as if the extra starting geometry had never been there. However, now the design has changed slightly and it's no longer possible to create a generative design even though the setup is the same except for some changes in the geometry. Do you know whats the cause for this?

thank you and kind regards, 

Merlin