Spotflag in interface type 2

Altair Forum User

Hello everyone.

 

I would like to ask you for some information about difference between Spotflag 1 and 5 (0) in Interface type 2 (tied).

I am running explicit model of front seat with lot of seam welds areas, for crash analysis. If i use spotflag 1 (optimized for spotwelds and rivets), mass scaling raises about 5% comparing to default formulation 0 (5). As far as i know spotflag 1 is recommended for spotwelds and for BRICK elements in master surface, what is not exactly my case. My connection is shell elements (master) and spring2N (slaves).
So can you tell me, what are the differences between these spotlags, and which one should I use?
I will also appreciate some kind of mathematical / physical interpretation if it is possible.

Thank you very much in advance.

 

Daniel

Altair Forum User

Hi Daniel,

When option Spotflag =1 is used in the Interface Type 2, then there are added mass on master surface. Please check that the springs inertia  are not too large and that the slave nodes height with respect to the master segments is as small as possible. For Spotflag=5, it can lead to incompatible kinematic conditions.

 

When the flag is set to 1, the spotweld formulation is an optimized formulation:

 having no hourglass problem

 having constant connection stiffness

 recommended with under integrated shells (master)

 recommended for connecting beam, spring and shell slave nodes to brick master segments

 

Please go through the Theory Manual of RADIOSS for detailed description on tied interfaces.