Stiffness for interface Type 11, segment and element deletion

Altair Forum User

Hello Everyone,

 

I would like to know how the value of stiffness for interface T11 is calculated. Also, what is the aim and the difference in simulation's results between 'no node deletion' and 'when an element is deleted' ?

 

Thank you

Altair Forum User

Hi Elamiae,

Type 11 interfaces are used to simulate impact between lines for 1D mesh, or edges in shell and solid meshes.  When two surfaces contact, a stiffness is introduced to reduce the penetration's nodes of the other surface into the surface. The nature of the stiffness depends on the type of interface and the elements involved. The introduction of this stiffness may have consequences on the time step, depending on the interface type used.

Istf is the stiffness definition flag. Stiffness computed from both master segment stiffness Km and slave segment stiffness Ks is as follows:

 

Idel is the node and segment deletion flag. During contacts, when elements are deleted, using this option the segment can be removed from the interface. Using 1 option, when all the elements associated to one segment (master/slave) are deleted, the segment is deleted from interface. Where as for 2, the segment will be deleted if any one element is deleted from the corresponding segment. Default option will be no deletion of segments.

Please see the attached snapshot for a contact where Idel=2 and Idel=0 (no deletion) is used.

 

 

 

Altair Forum User

Thanks George.

I'm wondering too, how can we calculate the value of Ks and Km? I mean mathematically ? 

Altair Forum User

Hi Elamiae, 

 and .where S is the segment area; V is the volume of the solid, and B is the Bulk Modulus.

 

I recommend you to check the RADIOSS reference guide where all the parameters considered and calculations are described.