Normalized center-to-center strain analysis of packed aggregates

The resolution of conventional techniques of center-to-center strain analysis is limited by the degree of original anticlustering of centers on the analyzed plane. However, the three-dimensional anticlustering of packed objects does not result in equivalent anticlustering on two-dimensional planes through these aggregates. Size variations due to imperfect sorting further decrease the anticlustering of natural aggregates. For the Fry all-object-object separations method, these problems are manifested in vague point-density distributions and ambiguously defined strain ellipses.Normalization of center-to-center distances allows more precise determination of small initial and tectonic anisotropies in packed aggregates. On planes through packed aggregates, object spacing is a function of object size, shape and the distance between object margins. Dividing the center-to-center distance between two objects by the sum of their average radii eliminates variations due to object size and sorting. Analyses of synthetic aggregates of packed spheres and statically recrystallized iron show that normalized Fry diagrams form better-defined vacancy fields and sharper rims of maximum point density regardless of the original sorting and anticlustering in the aggregate. Normalized strain analyses of deformed aggregates also show greatly increased resolution, with variable initial and tectonic ellipticity resulting in a wider ring of high point-density.