Grid point forces from OptiStruct -> Runtime Error when Reading OP2 with more than 2 loadcases in one sim file

[qink1986]

Hello,

Similar Error(#710) occor when reading OP2 file when more than 2 loadcases in one file.

Description:
When parsing an OptiStruct-generated OP2 file when more than 2 loadcases, PyNastran crashes with a FortranMarkerError and RuntimeError during the reading of the OGPFB1 table.

Error Log:

ERROR: op2_reader.py:4897 isubtable=-8  
...  
pyNastran.op2.errors.FortranMarkerError: imarker=0; markers=[-8, 1, 0]; marker_actual=(-10, 1, 0) table_name=b'OGPFB1'  
...  
RuntimeError: marker0 < isubtable; marker0=-10 isubtable=-8

Additional Context:
No results show in GUI, when only one loadcase contained.

Attached test files show the issue occurs specifically with OptiStruct's handling of GPFORCE data.
01_bar.zip

Request:
Could you investigate the parsing logic for the OGPFB1 table in OptiStruct OP2 files? The error suggests a marker/subtable mismatch during binary read.

Thank you for your help!

[SteveDoyle2]

Yeah, GPFORCE aren't supported from Optistruct. The other model was too unwieldy to work with.

Do you have the bdf/dat/inp and F06/out file of the GPFORCE output in ascii text so I can compare? The op2 is kind of a black box, so I prefer to not guess.

[qink1986]

I'm sorry that I don't have access to abaqus, but I here is the fem file which generates the OP2 file. fem file structure similar to inp and bdf. and the inp file that transform in altair hypermesh, I not sure if it can run in abaqus, but I hope it helps.

01_bar_input.zip

[SteveDoyle2]

I'm just getting back to this.

I took a look at the files you provided and I need an example of the ASCII output file or I can't effectively parse the file. Only the input model is not enough.