Learning Forum

[mathys.le-guen]

I have a problem when solving the model in LS-DYNA. The simulation hangs on the generation of the mathematical model (at 10%) and then the calculation crashes. I've tried to solve this problem by several means, thanks to research on forums etc. : 
- mesh modification
- modification of analysis settings 
- changing geometry 
- Tools --> Solver Process Settings --> Advanced --> Uncheck the "Distribute Solution if Possible" box.

But I'm still having the same problem, and it's also persisting on a "clean program", which was working fine before. 

PS : I can't put any attachement, as well as jpg or png

[Pedram Samadian]

Hi,

Thanks for contacting us. The provided information is not enough to identify the problem. Such an occurrence typically points to issues with the solver version, model setup, memory allocation, or configuration. Would you please let me know which version of the LS-DYNA solver did you use? I recommend running the model with newer versions of LS-DYNA. It is also worth trying to run the input.k file gerenated by Mechanical using LS-RUN.

Here are some other tips to troubleshoot and possibly resolve the problem:

 Check for Errors in the Input File:

• Review the message files, the D3HSP files, and the D3KMP files, which can contain valuable information for diagnosing the issue.
• Analyze binary outputs such as the DTI2 file and any results in the D3PLOT file and BINOUT file 
• Use built-in checkers in pre-processors (e.g. the Model check option in keyword manager within the LS-PrePost software) to review your keyword file and get feedback that might indicate the cause of non-convergence or other issues leading to the crash.

Verify Memory Allocation:

• LS-DYNA may need more memory for model generation. Try increasing the allocated memory in the command line or control settings.

Review Contact Definitions:

• Improper contact definitions can cause simulation hang-ups, especially in complex models. Check your contact settings, particularly for initial penetrations or mismatched surfaces.

 Set Up Initial Debugging Output:

• Enable *DATABASE_BINARY_D3PLOT and *DATABASE_GLSTAT output at a higher frequency, so you can capture initial calculations and troubleshoot where the problem might arise.
• Look into the GLSTAT file output for any warning or error messages generated before the crash.

Use Reduced Element Count for Testing:

• Simplify the model by reducing the number of elements or constraints temporarily to isolate the issue. This can help identify whether the model complexity itself is causing memory or stability issues.

Check Boundary Conditions and Loads:

• Verify that all loads and constraints are properly applied and ensure nodes aren’t double-constrained. Incorrect or conflicting boundary conditions can cause instability during model generation.

I hope the provided guidance helps.

Thanks,

Pedram

 

 

[mathys.le-guen]

Thanks for your reply. Here's the error I get: 

*** Error 41274 (SOL+1274)
cannot allocate dynamic memory
Ran out of memory allocating 987480 words
for sbc iheads array
E r r o r t e r m i n a t i o n

[Pedram Samadian]

Hi,

Thanks for the info. The message indicates that LS-DYNA is unable to allocate enough memory for the mentioned array either due to a shortage of available memory or improper allocation settings. Please check out the following possible solutions to address this error:

1. Increase Memory Allocation:

   • Adjust the memory in the LS-DYNA input deck to ensure that sufficient memory is available for allocation. For further information, please check out the *keword section in the LS-DYNA User Manual Vol. 1 (LSDYNA Manuals).

2. Optimize Model Size and Complexity:

   • Simplify the model if possible by reducing the number of elements, contacts, or parts that may be contributing to excessive memory usage.

3. Check Available System Memory:

   • Ensure that your system has enough RAM to support the model's requirements. LS-DYNA will try to allocate memory based on the model setup, and if your system’s physical memory is limited, it could lead to this error.
   • If running on a cluster or HPC system, verify with the cluster settings or administrators that enough memory is allocated per core or job.

4. Run a Test with a Smaller Model:

   • Try running a smaller version of your model (e.g., with fewer elements or a shorter simulation time) to confirm that the memory allocation is working correctly. This can help identify if the issue is purely memory-related or possibly due to model complexity.

5. Review Version-Specific Issues:

   • Older versions of LS-DYNA may have bugs or limitations related to memory allocation. You can try using the latest version.I hope this information helps you resolve the issue.

Thanks,

Pedram