Effect of loading history on cyclic stress–strain response

An attempt is made to rationalize the effect of loading history on cyclic plasticity in terms of interaction between the cyclic plastic strain and the unidirectional plastic strain, which is either pre-set (pre-deformed materials) or inevitably arises during fatigue tests (cycling with nonzero mean stress, effect of start-up procedure, ramp loading). In the case of easy-cross-slip metals, the relation between the cyclic and unidirectional plastic strain components is shown to be non-monotonous. This forms a basis for the unifying discussion of the effect of pre-strain, mean stress and start-up procedure of fatigue tests on the cyclic stress–strain response.