Learning Forum

[Jason Tran]

Hello,

I am trying to simulate the compression of a S shaped unit cell auxetic strcture; however, during the compression, the bodies will penetrate into each other despite contacts being present. 

Please see image below for a refernce of my solid body. I have applied a sweep mesh all around the body with automatic sizing, have added frictional contacts between penetrating surfaces, and have large deflections set to on. 

As for the boundary conditions, I have fixed the bottom face of the structure while putting a displacment of -6mm on the top face of the structure. When I run the solution, I get the results shwon in the second picture, despite putting contacts at those locations. 

Can someone please help to offer any advice as I have been stuck on this for mutiple days now.

Thank you so much for any advice in advance!

[Erik Kostson]

 

Hi

You would need to define contacts at all areas that can as you show intersect.

If you have defined contacts – post an image of all the contacts and their settings so forum members can see and provide feedback.

All the best

Erik

 

[Jason Tran]

Hi mark,

Thank you for your reply. I have added contacts at all the surfaces that show penetration. The contact surface and target can be shown in the picture below. 

The only settings I have changed in the contact region is changing the contact type to fictional with a coefficient of .2. Please see the second image for reference. 

 

[peteroznewman]

Hi Jason,

I have had good results using Explicit Dynamics to solve self contact models because that is automatically included in the model with no user input required.

You have to rethink the boundary conditions from Statics to Dynamics, but even using the displacement input you have might work when you provide a shorter end time than 1 second to reduce the compute time. Try 0.01 seconds.  This will create a constant velocity motion.

Regards,
Peter

[Jason Tran]

Hi Peter,

I have tried running it in explicit dynamics with the same boundary conditions with an end time of .005. However, I get different results than for static structural. For example, if I only apply -4mm of displacement there is no pentetration in the structure but i get different total deformation values. 

Do you have any advice for this? 

Thank you in advance sir

[peteroznewman]

Try rerunning at .05 second end time and see if the difference between that and Static Structural is smaller.