Learning Forum

[mahmoud14]

Hi everybody.
I am going to model a simply supported with torsional spring (semi rigid connection) in Workbench.
does any body have any idea on it? I want to do a per-stressed analysis on it.
Many thanks,
Mahmoud

[Ashish Khemka]

Turn on the beta feature and you will be able to see the torsional spring option.

Regards,

Ashish 

[jj77]

The only way I can think of is to model the springs at the end explicitly (just add two small line bodies at the end of the beam), restrain (extra line bodies that will be springs) them fully at their ends, apply force on the end of the beam, restrain the opposite beam end as needed, and on the same end as the force of course (not though the dof that is in the force direction of course), and that works. These two end line bodies are also converted to combin14 3D torsional spring elements. More details (including commands snippets) can be seen in the attached (beta option is easier). 

 

Normally one applies a pre load/stress, that keeps the supports where they are. In order to do that the only reasonable way is to apply a bolt preload, that works fine, and applies the pre tension say on the beam, something that should increase the freq. of say the bending modes.

 

 

 

 

 

 

 

 

 

 

 

 

[mahmoud14]

Hi Deae Jj77 Thank you so much for your reply.
I have added the springs from connection, joints,revolute.body fi ground.
Now , before any forces, by increasing the stiffness, it works well. The problem is when i have force on the top of the beam, to have a pre-stressed analysis.
My force has no effects on the results! With F=1 N and F=1000N, it gives the same frequency.
It seem it is account on the solution.

[mahmoud14]

Thank you akhemka I did it, but i used revolute from joints.
Many thanks

[jj77]

The revolute joint is blocking all dof except of the rotation (RZ), thus the applied force is cancelled out, thus not doing anything (by the dof restrains).

You could see this by plotting the displacements for the static analysis, and you will not see much going on.

 

Thus remove/delete the revolute joints completely, and replace them with two springs, top and bottom.

 

As mentioned above (use the beta option and when defining the spring to ground, there is a torsional option which I did not know) the only way I can think of is to model the springs at the end explicitly (just add two small line bodies at the end of the beam), restrain (extra line bodies that will be springs) them fully at their ends, apply force on the end of the beam, restrain the opposite beam end as needed, and on the same end as the force of course (not though the dof that is in the force direction of course), and that works. These two end line bodies are also converted to combin14 3D torsional spring elements. More details (including commands snippets) can be seen in the attached.

Normally one applies a pre load/stress, that keeps the supports where they are. In order to do that the only reasonable way is to apply a bolt preload, that works fine, and applies the pre tension say on the beam, something that should increase the freq. of say the bending modes.

[mahmoud14]

Thank you so much Many thanks. I will try this, to see my results.

[jj77]

No worries.

 

I think what you have done should/could work (revolute joint), if you apply the load as preload/tension (Loads/bolt pretension), and not by a force at the same location as the revolute joint (then it will cancel the force).

 

The proper way though is to use springs instead of joints.

[mahmoud14]

Dear JJ77,
Many thanks for your help.
It works well with that.
Many thanks again.

[jj77]

Good, but I found that they create weird BC on a pinned beam, hence why it is better to use springs (they do not influence the BC, except of RZ/torsion of course).

[mahmoud14]

Thank you.
Do you know how I can import a 2D AutoCAD  file as a section! to ANSYS workbench and assign it to a line body.
Many thanks

[jj77]

I would recommend opening up a new discussion for this.