Multiaxial fatigue life predictions by using modified manson-coffin curves

In the present study, a novel multiaxial strain based approach is proposed and validated using a number of data sets taken from the literature. The plane experiencing the maximum shear strain amplitude (critical plane) is assumed here to be coincident with the micro-crack initiation plane. The proposed technique requires the calculation both of the shear strain amplitude and of the maximum normal strain relative to the critical plane. Multiaxial fatigue life predictions are made by means of bi-parametric modified Manson-Coffin curves, which take into account the mean stress effect as well as the influence of non-zero out-of-phase angles.