An intrinsic dissipation model for high-cycle fatigue life prediction

This paper introduces a new intrinsic dissipation model for high-cycle fatigue life prediction of metallic materials. A general constitutive model with internal state variables, in accordance with the thermodynamic principles, is firstly formulated to describe the thermo-mechanical response of metallic materials under high-cycle fatigue loading. The model formulation considers two types of micro-mechanisms, i.e. the recoverable microstructure motion inducing anelasticity and the unrecoverable microstructure motion inducing damage. The intrinsic dissipation model is then derived taking into account two critical stress amplitudes related to the corresponding microstructure motion. Finally, a fatigue life prediction model is obtained by taking as a fatigue damage indicator, the intrinsic dissipation part induced solely by the unrecoverable microstructure motion, and as a failure criterion, the concept of energy dissipation threshold. The application is made on a FV520B stainless steel. Stepwise-amplitude and constant-amplitude experiments are used to identify the model parameters and the model prediction capabilities are verified by comparing the model-predicted S-N curve with the experimental results issued from traditional fatigue measurements. The underlying physical mechanisms are discussed by analyzing the stress amplitude and plastic pre-strain effects on the intrinsic dissipation. (C) 2018 Elsevier Ltd. All rights reserved.