Resultant Load from model.load_vectors

[Nick Katsinas]

I came across this issue which suggested that I should be able to calculate the OLOAD Resultant by summing the data in model.load_vectors. This didn't match the Femap load summation result nor the F06 OLOAD table in a SOL101 analysis with automatic inertia relief.

I modified the deck by fixing the nodes at the -Z edge and removing the INREL card to check the result in a fixed-base model without inertia relief (same loads). In that model, the translational force components do match those in the f06, but the moments are all 0.0.

Are these results expected? Is there another way to obtain the OLOAD resultant? I made a parser to extract this from the f06 in the mean time, but it would be great if I could get everything from the OP2.

Thanks in advance for your help!

Reproducing the Issue

Code

from pathlib import Path
from pyNastran.op2.op2 import read_op2

file = Path(r"D:\test_model_inrel\cylinder_pressure_inrel-0000.op2")

model = read_op2(file)
resultant_subcase_1 = model.load_vectors[1].data.sum(axis=1)
print(resultant_subcase_1)


pyNastran Output from Inrel Model
[[-5.7220459e-06 -1.9073486e-05  7.1997801e-21  0.0000000e+00  0.0000000e+00  0.0000000e+00]]

pyNastran Output from Fixed Base Model

These outputs match Fx/Fy/Fz, but the moments are all zero (not the case in f06).

[[-6.0743738e+02 1.8223104e+03 -1.6335078e-15  0.0000000e+00  0.0000000e+00  0.0000000e+00]]

Expected Result
From Femap (Tools>Check>Sum Forces):
[[-607.4372  1822.312  0.  -1822.312  -607.4372  5.77316E-14]]

From F06

[[-6.074373e+02  1.822311e+03 -1.633509e-15 -1.822311e+03 -6.074373e+02  -5.857693e-05]]     

Model
cylinder_pressure_inrel-0000.dat
Versions
pyNastran.__version__: 1.5.0+dev.a49f528ca
platform.python_version(): 3.11.3
Nastran: NX 2312.0070