LS-DYNA runs into Segmentation Violation (SIGSEGV) error. What can I do?

Content:

1. Error message (Segmentation Violation)

2. Checknan option (Segmenation Violation)

3. Error message (MPI)

.

Error message (Segmentation Violation )

>>>>>  Process 18  <<<<<
 >>>>> Signal 11 : Segmentation Violation <<<<<

• wikipedia: http://en.wikipedia.org/wiki/Segmentation_fault

.

Possible procedure for the debugging of the LS-DYNA Error:

1. Is it possible to reproduce the LS-DYNA Error?

• Run the identical input with identical configurations
Compare the two runs: diff between both NODOUT and both GLSTAT files

• For MPP Run: extract NODOUT from the BINOUT* via l2a

--> No comparability: Hardware problem? (cpu, memory, disk, network, ...)

.

2. Identify the LS-DYNA Error

• activate checknan option (*CONTROL_SOLUTION, ISNAN=1)
• Check the energy progression (GLSTAT, MATSUM, if necessary SLEOUT)
  
  • Can irregularities be detected immediately before the termination?
  • Which structural parts are affected?

• Do elements fail immediately before the termination?
  
  • check-failed –l mes*
  • check-failed –pid –l mes* (Which PIDs are affected?)

• Which are the last messages in STDOUT / STDERR / mes00xx?
• Are there any problems with viscoplasticity (VP=1, “…did not converge”)?
  
  • check-hsp d3hsp –xcon mes*

• Have unreasonable contact settings been applied? (e.g. large penalties- or thickness scaling etc.)
  
  • check-hsp d3hsp –cfac

• Can initial penetrations be detected? How many? How large?
  
  • e.g. check-c mes* -buc –typ –typ

• Are there any problems with spot welds or tied contacts? (e.g. untied nodes = cold spot welds)
  
  • e.g. check-c mes* -select tied

• Within which phase the error occurs?

• Keyword processing, initialization, decomposition 1-3, solution

.

3. Debug-Run

• Switch-off „Plotcprs“ (velocity, stress, strain … available)
• Termination Cycle = <Error Cycle> - 1
• investigate last plot state w.r.t. max. velocities, max. plastic strains, etc..

.

.

Checknan option (Segmentation Violation)

How can I activate the checknan option?

• Command-Line:  checknan=1
• Keyword:     *CONTROL_SOLUTION, ISNAN=1

.

Which output is produced by checknan option?

• Output to screen (e.g. jobout (STDOUT)):

*** NaN detected.  Please check message file from processor for detail.
*** Error NaN detected on processor #         30  <<<

• Output to messag-files (e.g. grep ‘out-of-range‘ mes0030):

*** termination due to out-of-range forces
    number of nodes has out-of-range forces       364
    Node list:
    37502068  37502162  37502192  37502206  37502357 ....

.

Visualization of output by checknan option (nodes)?

• DYNA Tool:    check-failed  –xnan  –a4nan
• Animator:  Read in the Session-File ´fail-ide.ses´

.

What does NaN mean?

• NaN („Not a Number“): http://en.wikipedia.org/wiki/NaN

• Node forces/ -moments/ -velocities with NaN occur due to different reasons – e.g. division by zero

• http://www.dynasupport.com/howtos/general/not-a-number-nan-1

.

check-hsp, check-failed, check-c, plotcprs are DYNAmore tools (free for customers: http://www.dynamore.de/tools)

.

.

Error message (MPI)

MPI Application rank 0 exited before MPI_Finalize() with status 13
 forrtl: error (78): process killed (SIGTERM)

• „…MPI_Finalize() with status 13“ is an MPI message due to a possible LS-DYNA  Error
  
  • Is not important for debugging of the LS-DYNA error.

gp 04/14