Energy models for fatigue life estimation under uniaxial random loading. Part I: The model elaboration

The paper contains analysis of the energy models for the fatigue life assessment under uniaxial stress state. From the simulation tests it appears that taking into account the stress and strain signs during determination of the energy density allows one to distinguish the strain energy density at the tension and compression path. Under random loading with the zero expected values for Gaussion processes it leads to the centered stochastic process. A new (basic for damage cumulation) material characteristic can be easily determined by rescaling the widely used standard stress and strain characteristics of cyclic fatigue. A new model of the fatigue life determination has been proposed. This model is based on the parameter of strain energy density. If the energy parameter is greater than zero, the strain specific energy is equal to this parameter and the material is subjected to tension. If the energy parameter is less than zero, the strain specific energy is equal to the absolute value of the parameter and the material is subjected to compression.