Contact Penetration
 
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Contact Penetration

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Posts: 8
Topic starter
(@viky113)
Unpaid Intern
Joined: 3 years ago

Hi 

I have a contact penetration problem while using a soft=2 contact between foam and steel. A part of the foam does not recover after compression. It does seem like there is a specific node that gets attached to the steel structure. I tried using a scale factor of 2 on the slave/master contact stiffness but it did not help. When I went higher on the scale factor, I ran into mass increase issues on the foam. Is there a way out of this? I am attaching the picture for the issue, with the indentation highlighted in blue.

 

Thanks

Vikram

 HeadRestraint Post Contact Issue
4 Replies




Posts: 36
(@geardyn-1)
Lab Tech
Joined: 4 years ago

use *CONTACT_INTERIOR

or USE Single surface contact as well

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Negative Volume
Posts: 639
Admin
(@negativevolume)
CEO
Joined: 5 years ago

@viky113 try soft=2 and depth=5 and reset your contact stiffness back to default of 1.0. You are using *Contact_automatic_surface_to_surface I assume? You can also try to change the entity type to segment sets if a region is giving you issues. And yes, include any soft parts in a *Contact_interior

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Posts: 8
Topic starter
(@viky113)
Unpaid Intern
Joined: 3 years ago

I tried a lot of different ways of going about this. I still have some penetration problem. See the attached picture. Its a cross section at which the penetration is visible. Let me quickly give summary of what we are looking at in the picture. There is a head restraint foam tied to the red plate. Boundary prescribed motion rigid has been applied to the face opposite to the face to which the foam is tied. There is a post inside the foam. As the dummy head moves rearward into the foam during the impact, there is penetration into the foam around the curved part of the post where the foam elements are highly compressed. Also, the foam elements in between the post and red plate are highly compressed, ultimately resulting in error termination from mass increase. There's a lot of things going on in there. 

For both dummy head to foam and foam to post contacts, I am using SOFT=2 and Depth=5 in automatic surface to surface contact. I used segment sets. My foam is also included in an interior contact. 

What would you recommend? I don't want to go lower on the timestep and as my rest of the simulation is optimized for it.

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Negative Volume
Admin
(@negativevolume)
Joined: 5 years ago

CEO
Posts: 639

@viky113 Is the foam nodally connected to the green curved bar? And is the bar rigid?

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