I am trying to simulate a model with a real geometry on NX 8.5. I have the mesh finished, using some mesh mating conditions and some face-to-face gluings. But now, I am trying to run first simulations and it does not work.
The message i get is the classic: Error opening NASTRAN F06 file.
Diag file shows nothing.
When I read the log it shows a message:
*** MEMORY REQUEST EXCEEDS LP-64 LIMIT OF 2047 MW ***
OPEN CORE Allocation Failed
Can you give me an advise what to do with it or where I can look for some more hints?
Solved! Go to Solution.
Depending the element type (and then the model size!!) used in the Fe model is possible that the default memory assigned to the NX NASTRAN solver is not enough to solve with success the FE model.
Without the model in hand, all I can tell you is the following:
The element iterative solver is supported by NX Nastran in linear static (SOL101) analyses only. You can include as well contact conditions in linear static (SOL101) analyses with the iterative solver. With the element iterative solver, the software works entirely from the element matrices. Use of the element iterative solver yields typical run time improvements of 4x to 6x compared to the global iterative solver. Additionally, the element iterative solver uses significantly less disk space. These performance gains are most noticeable with models composed of mostly solid elements.
There are several restrictions for using the element iterative solver. For example, the element iterative solver does not support superelements or inertia relief.
Please note that NX Nastran solver allocates all specified memory to the solver during a solve, which could affect other processes you want to run simultaneously.
You include the unit of measure with the value. For example, for 500 megabytes, enter 500Mb (no space between the value and the unit of measure). For 10 gigabytes, enter 10Gb. Depending the available RAM in your computer if you have more than 16 GB RAM, I suggest to start using a value of say 5GB, this is valid for most of the FE models.
Please note that the default LP-64 solver of NX NASTRAN only manage 8 GB of RAM, then if you allocate more RAM is useless. Only switch to ILP-64 solver if allocating 7.99GB of RAM is not anought, and then you get error. The LP-64 solver is faster than the ILP-64 solver..
To learn more about NX NASTRAN Hardware Requirements please take to my blog in the following address: https://iberisa.wordpress.com/2014/01/03/requisito
thanks for your insight... So it is most probably because of memory allocation for the solver.
I DO have the iterative solver checkbox checked... but I don't believe that it guarantees that the it. solver will be used. Can I check it somewhere in the log that he tried to run the it. solver?
For the memory textbox: It is only RAM? Or RAM + paging file Or RAM + Paging file + Scratch? From what you said i would expect that it is only RAM.
I found out that I had only minimal paging file allowed, so I reserved 50GB of Scratch SSD for paging. But I expect I also have to restart the PC for the system to recognize this new setting.
For description of my task: I don't need contacts, only gluings. I can also remove gluings if I would new it can help. I have 16GB Ram and free 300GB SSD for scratch. The model has cca 3M parabolic tetra elements. I am attaching the Log for more details.
In your log file I see the following:
Command Line: nx01-firstmodel-d_sim1-solution_1.dat prog=bundle old=no memory=8GB scratch=yes sdirectory=H:\Scratch sys442=1
mem=8GB is wrong, it gives error automatically, NX NASTRAN LP-64 only admit mem=7.99GB.
But please note this is a typical error form end users: to allocate a lot of RAM to the NX NASTRAN solver!!. Wrong, in most cases using simply mem=5GB is more tha sufficient, please note the OS need RAM memory to manage I/O, this is critical with NX NASTRAN, then do not waste your RAM memory allocating too much for the solver, let the OS to use it to speed I/O task, OK?.
Simply when solving any model take a look to the OS TASK MANAGER and see the ANALYSIS process, you will be surprised for the low value, this is the RAM used by the NX NASTRAN solver!!.
You say that you have an SSD disk, great!. This is critical to use the SSD disk as scratch directory for NX NASTRAN: make sure the NX NASTRAN keyboard SDIR points to that drive!!.
There are 2 versions of the 64 bit nastran solver executable:
If you need to specify mem >= 8GB, the ILP64 executable must be used. As Blas mentioned earlier, you may not necessarily need to ask for this much memory. Unfortunately, the only way to tell how much memory is actually needed is to make a run. This does not help if you only need to run a deck once, but if you make multiple runs, you can fine tune the memory requested to your particular model.
Blases answer helped me to run the model. But since we are discussing this I would like to clear up this topic.
So... Thank you, your answer uncovers the mystery a little bit more... only one question is unanswered here: Is there a way to tell NX which executable it should use? I did not found an option for this.
Regarding from where to select one solver or another, I told you before, in the second picture I posted yesterday: go to the EDIT SOLVER PARAMETERS > SOLVER EXECUTABLE and instead to use the environment variable (remember, you set this value previously using File > Utilities > Customer Defaults) simply set OFF and browse to the nastran bin directory on <NXAdvSim_Install_Dir>\NXNASTRAN\bin\nastran64L.ex
If you have only 16 GB of RAM, I strongly recommends you to continue using the standard LP-64 solver of NX NASTRAN, is faster than the ILP-64, you can try both solvers and compare execution time using a big FE model with say 3 million nodes, OK?.