Determination of LCF Plastic and Elastic Strain Components of Steel

The behavior of steel in low-cycle fatigue (LCF) is tested experimentally, in accordance with ISO 12106:2017 (E) and/or ASTM E 606-04. For this purpose, smooth specimens which are exposed to low-cycle fatigue at several levels of regulated strains and/or loads at room, elevated or reduced temperatures are used. Stress–strain response at LCF has the shape of an ideal hysteresis loop. The strain range Δε corresponds to overall loop width, while the stress range Δσ corresponds to its overall height. The paper presents a method for determining the intersection of the idealized hysteresis loop and the positive part of the strain axis in order to determine the values of elastic, Δεe/2, and plastic, Δεp/2, components of the strain amplitude to characterize the behavior of steel under low cyclic fatigue. The values of elastic and plastic components of the strain amplitude are needed to determine the characteristic curves of low-cycle fatigue, which describe the behavior of steel under the loading of low-cycle fatigue