In general, during LCF test for SSFS specimen, the strain deformation
can be achieved by the applied displacement dividing the total effective
gauge length. However, as can be seen from Fig.6b, it is very difficult
to directly calculate the strain deformation since the length between
the extensometers consisting of a parallel gauge length and transition
fillet radius, thus, a useful deformation correlation between the
parallel uniform gauge length (l0 ) and transition
lengths could not be obtained. In the previous study, the researchers in
the work57 utilized the reference stress approach to
allow conventional creep data to be obtained from impression creep test
data. Based on the same conception, the authors’ have proposed a new
reference strain approach for scaling factor identification. On the
basis of this, an empirical relationship between the parallel gauge
(l0 ) and the total effective gauge length
()
is proposed based on the proposed scaling factor, β , as shown in
Fig.6b. The total effective gauge length can be formulated, as follows: