The data consists of measurements of 435 final cracks for the three specimens. This breaks down as 190 final cracks measured at 4 times for the 140kN data, 185 final cracks measured at 8 times for the 160kN data and 60 final cracks measured at 7 times for the 200kN data. Some final cracks that were measured consisted of a set of coalesced smaller cracks. This was observed in the 200kN data in particular, with each final crack consisting of up to 23 smaller cracks.
The data is plotted in
Figures 
, and .
These are plots of the total length of the cracks which were
present at the final observation point, versus number of cycles.
The raw data exhibits a feature known as `coalescence' which has
to be dealt with. Coalescence is the process by which two cracks,
which are spatially close, combine to form one single crack. This
phenomenon is dependent upon how many cracks are in a specimen,
and how they are spatially distributed [4],
[60]. This can be an important mechanism for crack
elongation, and is dealt with in some detail in
Chapter and Chapter .
The primary focus of the original analysis is concerned with modelling growth of single cracks throughout time. Interactions, and thus coalescence, will not be considered directly in this chapter.
