Learning Forum

[Gasper Bizjan]

Hello everyone,

I have a static structural analysis using large deflections as in the picture below. I would like to deform the part and bond it once the two lines touch.
Finally, I want to release the forces that cause the deformation, but I would like the parts to stay glued together. How can I do that?
I tried using bonded contact but it doesn't work since there is an initial gap.

The process is showed from left to right and as you can see, the surfaces separate. 

 

Thanks for the help and regards.

[Erik Kostson]

 

 

Hi

Perhaps use 3 steps with contact step control (we need 2 contacts defined) – so first step move part until they touch (frictional contact is 'alive' bonded is 'dead' – move as needed down to cover the gap between the parts), 2nd step change the contact to bonded (from frictional say in 1st is 'dead' now and the bonded contact is 'alive' now), and 3rd remove the enforced movement from the top.

 

See about step control of contacts here:

https://www.youtube.com/watch?v=EJAFX5lMBbg

https://featips.com/2022/09/28/how-to-activate-deactivate-contacts-in-ansys-workbench/

All the best

Erik

 

 

[Gasper Bizjan]

It worked for the Static structural! I was able to activate the bonded contact. But I am now trying to run a Modal analysis and the contact keeps disappearing.

I think I selected the correct load step in the modal analysis Pre-stress settings. Any idea what might be the issue?

Thank you and regards.

 

[Erik Kostson]

See this for explanation on what you observe:

https://forum.ansys.com/forums/topic/modal-analysis-with-pre-stress/

 

[Gasper Bizjan]

This method in the video above does not work since:
1) either I can't use connections (contact step control does not work in Modal) so the two sides don't bond
2) I can use the deformed geometry with contacts, but can't use the stiffness matrix from pre-stress

 

My problem is that the deformation itself changes the part from two to one rigid body. Since the modal analysis doesn't bond them I can't get the correct mode shapes. But if I use just the deformed mesh and bond it, then I don't get the correct stiffness since there is no pre-stress. 

Any ideas on how I can approach this problem? Thank you.