PSI - Issue 28

Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2019) 000–000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000–000 ScienceDirect

www.elsevier.com/locate/procedia

www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 28 (2020) 1551–1558

© 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 © 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 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. © 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 1st Virtual European Conference on Fracture The influence of stress ratio on fatigue lifetime of NiTi shape memory alloy V.Iasnii*, P. Yasniy Ternopil Ivan Puluj National Technical University, Ternopil 46011, Ukraine 1st Virtual European Conference on Fracture The influence of stress ratio n f tigue lifetime of NiTi shape memory alloy V.Iasnii*, P. Yasniy Ternopil Ivan Puluj National Technical University, Ternopil 46011, Ukraine Abstract 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. 1. Introduction Shape memory alloys (SMA) are functional materials which are characterized by shape memory effect and pseudoelasticity. Due to these properties, they are widely used, particularly, in bioengineering (Morgan 2004; 1. Introduction Shape memory alloys (SMA) are functional materials which are characterized by shape memory effect and pseudoelasticity. Due to these properties, they are widely used, particularly, in bioengineering (Morgan 2004; Abstract Keywords: pseudoelastic alloy; stress ratio; energy dissipation; strain raing. Keywords: pseudoelastic alloy; stress ratio; energy dissipation; strain raing.

* Corresponding author. Tel.: +380-352-519700. E-mail address: v_iasnii@tntu.edu.ua * Corresponding author. Tel.: +380-352-519700. E-mail address: v_iasnii@tntu.edu.ua

2452-3216 © 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 2452-3216 © 2020 The Authors. Published by EL EVIER 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

2452-3216 © 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 10.1016/j.prostr.2020.10.127