Additionally, it is interesting that the starting points of the
creep process at each higher stress level lies on a static stress–
strain curve when using a creep program without the return.
Regarding to the Mullins effect the starting points of the creep process when using a creep program with the return should be positioned on exactly the same location as well. As is already
explained in Section 3, we ascertain that this is not the case when
cyclic loading is applied on the investigated material. This means
that some permanent softening appears during the discharging.
We observed this effect in the stress relaxation measurements as
well and present it in Fig.7.