Nastran SOL 101 and SOL 106 difference

[tataaero]

Hi,

I have a model that works in SOL 101.

I would like to model a small region of this model with non-linear material properties.

When i made the necessary changes, the model no longer ran. So I ran the changed model as a SOL 101 (without the NLPARM and plastic material) and it runs fine.

Before i get to the error in the SOL 106 f06 file, there is a warning about DOF having high factor diagonal ratios...this message would usually be followed by a FATAL excessive pivot ratios error in SOL 101, however in SOL 106 it keeps running (also this message doesn't appear in the SOL 101 run).

The actual FATAL message is:
*** USER WARNING MESSAGE 4675 (NMEPD)
EXCESSIVE INCREMENTAL LOAD IS APPLIED IN ELEMENT
REDUCE THE LOAD INCREMENT BY A FACTOR OF 5.010000E+02 FOR BETTER SOLUTION .
*** USER FATAL MESSAGE 4676 (NMEPD)
ERROR EXCEEDS 2.000000D+01
PERCENT OF YIELD STRESS IN ELEMENT

And this message occurs when i don't include the non-linear material. So I believe the problem is due to the warning message...but i can't seem to figure out why since the model is constrained correctly for the SOL 101 run. Are there any differences between SOL 101 and SOL 106 that would cause the high factor diagonal ratio problem? The nodes that have the high factor diagonal ratio are connected to free ends of bar elements and have applied loads.

Thanks

 

[rb1957]

if "plastic material" needs above yield, then yes SOL101 won't work ('cause it's linear elastic).

so you're using SOL106 ... NASTRAN is telling you in pretty plain speak what to do ...
"EXCESSIVE INCREMENTAL LOAD IS APPLIED IN ELEMENT
REDUCE THE LOAD INCREMENT BY A FACTOR OF 5.010000E+02"

Quando Omni Flunkus Moritati

 

[inline6]

having no idea what you are modelling, could the part be buckling?

how do you get the same message about yield stress when you have a elastic material?

in general SOL 106 is so 1990's it is not robust at all if there is "alot" of nonlinearity. look to use SOL 400 or 600 if possible