THEORIES OF PLASTICITY UNDER CYCLIC LOADINGS
Versions of the theories of plasticity currently used in applied engineering design - Korotkikh, Bondar and Chaboche models - are considered. The effect of various types of micro-stresses on the behavior of the hysteresis loop under uniaxial soft asymmetric cyclic loading consisting of several blocks is analyzed. It is shown that, for detailed modeling of the ratcheting of the hysteresis loop arising under such loading conditions, all three types of micro-stresses must be used. This conclusion is corroborated by the results of the experimental studies of samples made of stainless steels SS304 and 12Ch18N10T under soft loading, where both direct and reverse ratcheting was observed. It is shown that the modified Bondar model accounting for Ohno - Wang micro-stresses (the third type) is the most adequate one in describing the ratcheting processes of the elastoplastic hysteresis loop, including the reverse ones.