KitanaOR
Aerospace
- Mar 16, 2011
- 1
My group had been using NX NASTRAN 1.0.1 and was upgraded to 6.0. My models have temperature-dependent CTE tables (MATT9, TABLEM1) and temperatures are applied as a load onto each node.
We've learned through experiment and RTFM that our former case control is no longer valid if we want to use the CTE at the load temp, not at TEMPERATURE(INIT):
SOL 101
TEMPERATURE(INIT)=10
TEMPERATURE(LOAD)=100
TEMPD,10,50.,100,200.
Now it's TEMPERATURE(BOTH)=100 and TREF in MAT9 is 50.0.
On my simple one-element or 3X3X3 element models, I get the exact same results as I had gotten using version 1.0. BUT when I apply what I learned to my more-complicated, proprietary model, I get results that vary in % from node to node.
The bigger model uses CHEXA, CPENTA, CELAS2, and RBE2, but I have isolated a section of the mesh that just had CHEXA and got the same 6.0 results. (The mesh is separate sections that don't influence each other.) This model is also supposed to use the material orientation vectors as defined in I-DEAS, but I am having trouble verifying the coordinate system in the bulk data to the mat orientation vector in I-DEAS.
The version 6.0 user guide describes exactly which CTE it uses, different from 1.0's user guide. Are there any other changes in the solver that could help explain why I get different results?
Why is it when I make the change from TEMP(INIT) and (LOAD) to (BOTH) in NX NASTRAN 6.0, I'm not getting the exact same results that match my version 1.0 results like I did in my smaller models? Thanks in advance for the help.
We've learned through experiment and RTFM that our former case control is no longer valid if we want to use the CTE at the load temp, not at TEMPERATURE(INIT):
SOL 101
TEMPERATURE(INIT)=10
TEMPERATURE(LOAD)=100
TEMPD,10,50.,100,200.
Now it's TEMPERATURE(BOTH)=100 and TREF in MAT9 is 50.0.
On my simple one-element or 3X3X3 element models, I get the exact same results as I had gotten using version 1.0. BUT when I apply what I learned to my more-complicated, proprietary model, I get results that vary in % from node to node.
The bigger model uses CHEXA, CPENTA, CELAS2, and RBE2, but I have isolated a section of the mesh that just had CHEXA and got the same 6.0 results. (The mesh is separate sections that don't influence each other.) This model is also supposed to use the material orientation vectors as defined in I-DEAS, but I am having trouble verifying the coordinate system in the bulk data to the mat orientation vector in I-DEAS.
The version 6.0 user guide describes exactly which CTE it uses, different from 1.0's user guide. Are there any other changes in the solver that could help explain why I get different results?
Why is it when I make the change from TEMP(INIT) and (LOAD) to (BOTH) in NX NASTRAN 6.0, I'm not getting the exact same results that match my version 1.0 results like I did in my smaller models? Thanks in advance for the help.