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Microstructure Characterization 77
Two
Contacting Areas
(a) (b)
(a) Two Contacting Particles (b)Particles are Contacting at Many Points in Two Places
FIGURE 3.13 Illustration of the complexity of contact.
The determination of the existence of a contact can be made by the distances among
the surface points of two particles. Theoretically, this distance should be zero for two
particles in contact. However, due to errors involved in digitalization, the spacing and
thickness of sections, and the image processing required to separate particle cross-sec-
tions, two particles with a certain small distance are considered contacting particles. This
small distance is called threshold distance. The threshold distance must be determined
based on an overall evaluation of the above errors and equilibrium considerations.
Figure 3.14 presents the relation between the threshold distances and the corresponding
FIGURE 3.14 Number of particles in contact versus threshold distances.
