High-cycle and low-cycle fatigue interaction under 2-step strain control

Fatigue of mild steel under 2-step strain control of decreasing order with various mean strains has been studied for two different loading sequences. It was observed that cyclic softening in the second step is stabilised by the presence of the first step and either positive or negative mean stress may be induced in the second step. The average damage summations, both with and without mean strain correction, are found to be close to unity. Fatigue damage accumulation has also been analysed using Continuum Damage Mechanics modelling, which helps identify the sources of the deviation of the damage summation from unity and the non-linear accumulation of damage.