塑性ひずみ基準による鋼の疲労損傷則

抄録

A fatigue damage rule of a structural steel based on plastic strain ranging from high-cycle to low-cycle fatigue regime is proposed, especially paying attention to load sequence effect. Four types of fatigue tests including i) constant strain amplitudes, ii) mean strain amplitudes, iii) surplus and iv) reversible strains against the foregoing half cycle were conducted. The fatigue damage was evaluated at each half cycle, so that a loading sequence may be evaluated in a unique manner. The fatigue damage rule was optimized for these fatigue tests and also compared to rules by other researchers.
The load sequence effect (Hi-Lo or Lo-Hi) was found to exist but small in strain criterion compared to that in stress criterion. A step-wise strain increasing test was compared to a step-wise stress increasing test and resulted that coaxing effect was not big under strain controlled condition.