I have a problem with nastran sparse fbs.
I have two quite big SOL 101 Inertia Relief jobs with just few small geometric differences between them.
The calculation of the first of them takes approximately 7 hours, the second one needs however about 20 hours.
I looked into the .f04's und found out, that the fbs module is mainly responsible for this huge difference in computing time:
FBS METHOD S2 TIME ESTIMATE TO FORM UL1 - CPU= 6121, I/O= 493, TOTAL= 6614, PASSES= 110:39:22 44:02 873.1G 5.0 8414.6 0.0 FBS BEGN11:02:33 67:13 1088.3G 215.2G 12095.5 3680.9 FBS END
for the first model and:
FBS METHOD S1 TIME ESTIMATE TO FORM UL1 - CPU= 24880, I/O= 497, TOTAL= 25377, PASSES= 1
17:54:32 45:12 873.4G 5.0 8780.7 0.0 FBS BEGN7:43:37 874:17 1089.9G 216.5G 58390.8 49610.0 FBS END
for the second.
Could anyone tell me what FBS METHOD S1 and FBS METHOD S2 really are and if I can force using one them instead of letting nastran decide?
I use nastran 9.1 ILP-64 with 12 cores and following settings:
NASTRAN BUFFSIZE = 65537
NASTRAN SYSTEM(146) = 4NASTRAN SYSTEM(206) = 72