Lifetime estimation in the low/medium-cycle regime using the Carpinteri–Spagnoli multiaxial fatigue criterion

A critical plane-based high-cycle multiaxial fatigue criterion, known as the Carpinteri–Spagnoli (C–S) criterion, is here extended to evaluate the fatigue lifetime of plain metallic components under constant amplitude loading in the low/medium-cycle regime. This extended criterion, based on strain components, resolves the strain tensor into the normal and shear components acting on the critical plane, which is determined on the basis of the principal strain courses over the loading cycle. An equivalent normal strain amplitude, computed through a quadratic combinations of strain components in the critical plane, is taken as the fatigue damage parameter. The required input parameters of the criterion are obtained from the classical Manson–Coffin–Basquin law for axial loading. A validation by experimental data pertaining the biaxial fatigue of plain steel specimens under both proportional and non-proportional loadings is performed.