AUTOSPC=YES Vs K6ROT=1 in Nastran

[rootsandwings]

I got 0.5 Hz higher frquency when I used K6ROT=1 instead of AUTOSPC=YES while working on a structure which has a 1st frequency of about 15 Hz. The model is essentially built with CQUAD4 elements and with a few CHEXA and beam elements.
Please adivse if anyone has a specific recommendation on the choice.

 

[shlr1]

My recommendation is to use both commands (K6ROT =10.
and AUTOSPC=YES)
shlr