ABSTRACT
In order to detect the Mullins re-activation on pre-stretched samples, Merckel et al. (2012) proposed to submit the pre-stretched specimen to cyclic uniaxial loadings with maximum stretching increasing slowly at each cycle. With such a cyclic loading, it was observed that the material loading responses superimpose as long as the Mullins softening does not evolve. Therefore when material loading responses between to successive cycles differ, the Mullins softening reactivates. Numerous parameters may be defined to quantify the difference between two successive responses
1 MULLINS CRITERION FOR GENERAL LOADING CONDITIONS
1.1 State of the art
In there early works on the Mullins softening, Mullins and his co-workers (Harwood et al. 1965, Harwood and Payne 1966, Mullins 1969) noticed that during cyclic tension of rubbers, materials were showing substantial softening between the first and the second extensions. The authors attributed this softening to localized non-affine deformations and they related its evolution to the applied maximum stretch (rather than maximum stress). This path has been mostly followed ever since.
