E4 Structure
Verfasst: Fr 17. Mai 2013, 21:27
AURORA TEAM:
Note please this case. It's a structure of K=178, E=325 type 4. Material: Structural Steel. Section: Tube D=20MM, d=15MM. Constraints in all directions at each of the four footholds. Load: Z-10000N at the lower central node of the tower's roof.
Initially the tower was designed with the sides of its base aligned with the XY axes. With this geometry solvers didn't calculate. This was the final message from the Z88R.log file:
start SCAL88
### diagonal element 31 zero or negative ..stop ###
### often caused by missing or wrong constraints ###
### recover: check constraints (underdefined ?) ###
### PARDISO error 3320:
This log points constraint errors but this didn't seem to be the problem. Then the whole structure was rotated 5º at the XY plane and other 5º at the YZ plane, in order to none of its elements were aligned with the XYZ axes (see please at the lower left of the image). With this new geometry and the same BLCs, SICCG and SORCG solver worked well but just with a 1.0E-004 Residuum. Cholesky and Pardiso didn't work at all. A single rotation in the XY plane worked fine for other simpler structures but not for this tower.
I wonder then why rotations were needed to solve this case, why it was necessary to reduce the residuum, and how reliable are the obtained results. On the other hand, I wonder also if I'm making any kind of mistake.
Thank you very much in advance. Regards.
Note please this case. It's a structure of K=178, E=325 type 4. Material: Structural Steel. Section: Tube D=20MM, d=15MM. Constraints in all directions at each of the four footholds. Load: Z-10000N at the lower central node of the tower's roof.
Initially the tower was designed with the sides of its base aligned with the XY axes. With this geometry solvers didn't calculate. This was the final message from the Z88R.log file:
start SCAL88
### diagonal element 31 zero or negative ..stop ###
### often caused by missing or wrong constraints ###
### recover: check constraints (underdefined ?) ###
### PARDISO error 3320:
This log points constraint errors but this didn't seem to be the problem. Then the whole structure was rotated 5º at the XY plane and other 5º at the YZ plane, in order to none of its elements were aligned with the XYZ axes (see please at the lower left of the image). With this new geometry and the same BLCs, SICCG and SORCG solver worked well but just with a 1.0E-004 Residuum. Cholesky and Pardiso didn't work at all. A single rotation in the XY plane worked fine for other simpler structures but not for this tower.
I wonder then why rotations were needed to solve this case, why it was necessary to reduce the residuum, and how reliable are the obtained results. On the other hand, I wonder also if I'm making any kind of mistake.
Thank you very much in advance. Regards.