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No Separation After Contact

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Posts: 21
Topic starter
(@kingoz79)
Paid Intern
Joined: 3 years ago

Hi,

Is there a way to model two parts in Ls-Prepost to remain in contact during the entire dynamic analysis? By that I mean there is no separation of the two parts after the initial contact.

Thanks

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Negative Volume
Posts: 668
Admin
(@negativevolume)
CEO
Joined: 6 years ago

Hi @kingoz79

You would need to define a tied contact between the two parts. There are a lot of different ways that you can do this so you will need to experiment a little to get something that works for you. I would suggest starting with defining a *Contact_automatic_surface_to_surface_tiebreak between the two parts that you want to "stick" and make sure that Option 1 is selected in the contact. You might need to define this with shell parts which you can do by coating 2D null shells on any 3D part.

https://www.dynasupport.com/howtos/contact/tied-tied-offset-and-tiebreak-contacts

 tied contact
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Posts: 61
(@icebreakersours)
Lab Tech
Joined: 4 years ago

If the contact isn't active initially, then you will need to prescribe Birth Time on the Tied Contact.

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Negative Volume
Admin
(@negativevolume)
Joined: 6 years ago

CEO
Posts: 668

@icebreakersours I've never tried to implement a contact where it "sticks" after impact but I believe that the way I described would be how to do it. Are you saying that you need to estimate when the contact touches to "birth" it? Seems odd. 

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(@kingoz79)
Joined: 3 years ago

Paid Intern
Posts: 21

@negativevolume I am modeling a soil-structure interaction and would prefer to avoid any non-linearity in the dynamic response (i.e. the analysis is basically elastic). I have decided to merge the contact nodes without using contact properties. Thus, the two parts are always in contact. Thanks for the help.

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Posts: 61
(@icebreakersours)
Lab Tech
Joined: 4 years ago

@negativevolume I am assuming something is happening ("..there is no separation of the two parts after the initial contact") prior to contact and as the entities come in to contact they should stick. Hopefully, I am not mistaken in my understanding of the posed question.

If the entities must be tied at t=0, then there is no need for using birth time. Otherwise, you are right in your interpretation. That is how I would go about it anyway; I haven't tested alternatives.

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