The influence of stress ratio on fatigue lifetime of NiTi shape memory alloy

The influence of stress ratio on fatigue lifetime of pseudoelastic NiTi alloy are studied. The stress-, strain- and energy-based criteria were used for analysis under on low-cycle fatigue. Increasing the stress ratio from 0 to 0.5 significantly reduces the fatigue life of the NiTi alloy when used to describe the stress range, strain range and dissipation energy density and increases when using the Odqvist's parameter. A good agreement between experimental and calculated values of predicted lifetime was obtained. The low-cycle fatigue failure criterion of pseudoelastic NiTi alloy - total elastic strain energy density that takes into account the stress ratio was proposed. (C) 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the European Structural Integrity Society (ESIS) ExCo