Obtained field container of a elemental result is longer than list of elements in model

[vymlatilp]

Hello,

we have example of model with 8 structural elements (cube with 8 solid elements). However the stiffness matrix energy returns field container with 12 values.

Is there an explanation? Are the energies listed also for surface elements used for loading? If so, it is not consistent with the fact that DPF works only with structural elements. Is there a way how to get a full list (including elements for loading, contacts, etc.), of elements and nodes in the model?

Code:

file_path = Path(r"01_structural_static.rst")
model = dpf.Model(file_path)
result = dpf.operators.result.stiffness_matrix_energy()
elements = model.metadata.meshed_region.elements
my_data_sources = model.metadata.data_sources
result.inputs.data_sources.connect(my_data_sources)
field_container = result.outputs.fields_container()
print(field_container[0].data)
print(elements)

Print:

[7.82110092e-08 7.82110092e-08 8.44442312e-08 8.44442312e-08
 0.00000000e+00 0.00000000e+00 7.82110092e-08 7.82110092e-08
 8.44442312e-08 8.44442312e-08 0.00000000e+00 0.00000000e+00]
DPF Elements object with 8 elements

Thank you and best regards,
Petr