Eroding contact question

[protra...@gmail.com]

Hello,

In general, for solids to solids contact, would Eroding Single Surface Contact (Soft=2) be enough or stacking it with another Automatic Single Surface Contact is better? Does Eroding contact also automatically check for slave to master and master to slave penetration?

Best Regards,

[James Kennedy]

Dear Protra,

 

Some notes of possible interest:

 

Eroding contact types are recommended whenever solid elements involved in the contact definition are subject to erosion (element deletion) due to material failure criteria.  These eroding contacts contain logic which allow the contact surface to be updated as exterior elements are deleted.

In *CONTACT_ERODING_NODES_TO_SURFACE/*CENTS, the slave side of the contact should be defined using a node set containing all the nodes (not just nodes on the outer surface) of the slave side part(s).

Eroding contact between solid element surfaces is defined so that the contact erodes as the elements erodes (*CONTACT_ERODING_SURFACE_TO_SURFACE/*CESTS).  This allows the contact to work correctly as layers of the parts erode during penetration.

---------------------------------------------------------

 From these notes I got four options for *CONTACT_AUTOMATIC_XXXX  and *CONTACT_ERODING_XXXX :

1. *CONTACT_AUTOMATIC_XXXX (with no interior elements generated)

By default, when a solid part ID is included in a contact slave or master part set, LS-DYNA generates a segment list for only the outer skin of the solid element volume.

2,  *CONTACT_AUTOMATIC_XXXX (with interior elements generated)

Generate the list of segments for the outer skin but it also generates the segments for ALL interior elements as well using PART_IO.

3, *CONTACT_ERODING_XXXX (with no interior elements generated)

These  eroding contacts contain logic which allow the contact surface to be  updated as exterior elements are deleted. (I found no details  explaining this.)

4. *CONTACT_ERODING_XXXX (with interior elements generated)

This should generate the segments for ALL interior elements using PART_IO. How this interacts with general (default) eroding logic is not stated. I simply made some test runs and found differences which indicated that this probably should be taken into account.

 

https://www.oasys-software.com/dyna/wp-content/uploads/2020/01/Intro-to-Contacts.pdf

 

https://www.dynaexamples.com/introduction/examples-manual/contact/eroding

 

https://lsdyna.ansys.com/contact-eroding-i/

 

https://lsdyna.ansys.com/contact-eroding-ii/

 

Sincerely,

James M. Kennedy

KBS2 Inc.

July 5, 2024

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