In all of previous analysis, the critical length
used is the value derived under a normally implicit
assumption that the fragmentation process
has reached the saturat-ed stage. As a result,
for a given twisted structure, this critical length
will be constant, and the strength of the system
thus becomes length-independent. We have
found that in the real cases, there are many variables
which affect the fragmentation process adversely
so tht, a saturated fragmentation state
is rarely realized, hence resulting the strengthlength
dependence experimentally observed