Statistical repeatability and calculation of“porosity volume
fraction”
The geometry for the models was created using a Python script. Python is
the underlying language for the Abaqus CAE tool (the pre-processor for
the Abaqus package), so this programme enabled much of the geometry
creation and meshing activity for the finite element models to be
undertaken automatically.
While it is reasonably possible to create large numbers of example
models, it is less reasonable to analyse each of them and present all of
those results, but it is reasonable to question the statistical
variation between results. To do this efficiently, the Python script was
modified, to remove the Abaqus specific instructions, and to carry out
some additional calculations for number of pores, total area of pores,
and the “porosity volume fraction” defined as being the total
area of the pores divided by the defined zone area.
Because the calculation for porosity volume fraction was based on the
area of the defined zone for pore centres, it is clear that this
definition is inadequate, because it fails to recognise that pores near
the edges of the zone can overlap. This problem is illustrated in Figure
4. The error is particularly significant for larger maximum pore sizes.