Experimental curves from samples tested in cell 1 hardly differentiate
from one to another, and significant force values are measured only after a 5-
mm displacement, upon a 10-mm initial gap between plates (Fig. 6). Sample
L reaches a higher force value (about 150 N) whereas sample J exhibits the
lowest resistance (close to 80 N), but standard deviation (SD) is important
(60 N for sample L). The induced repeatability relative error (±15%) is too large to conclude that there is a clear difference in behavior from the other
samples. Such a test should be adopted at a relevant scale, using a low amount
of samples, to measure the critical stress intensity of flakes, in analogy with
the procedure suggested by Vincent et al. (2002) and to correlate this observation
with crispness, but this is out of the scope of the present work.