PSI - Issue 68

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N. Bykiv et al. / Structural Integrity Procedia 00 (2025) 000–000

N. Bykiv et al. / Procedia Structural Integrity 68 (2025) 405–408

0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0

R(0.1); σ(500 MPa) R(0.5); σ(500 MPa)

R(0.1); σ(550 MPa) R(0.5); σ(450 MPa)

3

W dis , MJ/m

1

10

100

1000

10000

100000

N , cycle

Fig. 3. Change in the dissipated energy W dis of nitinol specimens depends on the number of cycles N of their loading with a stress ratio of 0.1 and 0.5 under different σ max

However, there is a noticeable difference in the dissipated energy for specimens with different stress ratios. For example, the difference in the dissipated energy, under the highest maximum stress of 550 MPa at the stabilisation region (100 th cycle), is 0.86 MJ/m 3 , which is 46%. Conclusions Increasing the stress ratio from 0.1 to 0.5 worsens the functional properties of the pseudoelastic SMA and mainly reduces the dissipated energy. At the 1000 th cycle under the maximum stress of 450 MPa, the dissipated energy is 3 times higher for R σ = 0.1 than for R σ = 0.5. At the higher maximum stress of 550 MPa, the difference in the dissipated energy increases to 4.2 times. References Bykiv, N., Iasnii, V., Yasniy, P., & Junga, R. (2021). Thermomechanical analysis of nitinol memory alloy behavior. Scientific journal of the Ternopil National Technical University , 102 (2), 161–167. https://doi.org/10.33108/visnyk_tntu2021.02.161 Chernenko, V. A., L’Vov, V. A., Cesari, E., Kosogor, A., & Barandiaran, J. M. (2013). Transformation Volume Effects on Shape Memory Alloys. Metals 2013, Vol. 3, Pages 237-282 , 3 (3), 237–282. https://doi.org/10.3390/MET3030237 López, G. A. (2021). Shape Memory Alloys 2020. Metals 2021, Vol. 11, Page 1618 , 11 (10), 1618. https://doi.org/10.3390/MET11101618 Pyndus, Y., Yasniy, O., Fostyk, V., & Maruschak, P. (2018). Assessment of Minimal Fatigue Crack Growth Rate After a Single Overload in D16chT Alloy. Iranian Journal of Science and Technology - Transactions of Mechanical Engineering , 42 (4), 341–346. https://doi.org/10.1007/s40997-017-0101-5 Stachiv, I., Alarcon, E., & Lamac, M. (2021). Shape Memory Alloys and Polymers for MEMS/NEMS Applications: Review on Recent Findings and Challenges in Design, Preparation, and Characterization. Metals 2021, Vol. 11, Page 415 , 11 (3), 415. https://doi.org/10.3390/MET11030415 Wang, Z., Luo, J., Kuang, W., Jin, M., Liu, G., Jin, X., & Shen, Y. (2022). Strain Rate Effect on the Thermomechanical Behavior of NiTi Shape Memory Alloys: A Literature Review. Metals 2023, Vol. 13, Page 58 , 13 (1), 58. https://doi.org/10.3390/MET13010058 Yasnii, V. P., Student, O. Z., Yasnii, P. V., & Nykyforchyn, H. (2021). Micromechanism of Propagation of Fatigue Cracks in Pseudoelastic NiTi Shape-Memory Alloy. Materials Science , 56 (4), 461–465. https://doi.org/10.1007/S11003-021-00451-3/FIGURES/3 Zhang, Y., You, Y., Moumni, Z., Anlas, G., Zhu, J., & Zhang, W. (2017). Experimental and theoretical investigation of the frequency effect on low cycle fatigue of shape memory alloys. International Journal of Plasticity , 90 , 1–30. https://doi.org/10.1016/J.IJPLAS.2016.11.012 Bykiv, N. Z., & Iasnii, V. P. (2022). Zastosuvannia splaviv iz pamiattiu formy u budivelnykh konstruktsiiakh. Suchasni tekhnolohii ta metody rozrakhunkiv u budivnytstvi , 17 , 3–14. https://doi.org/10.36910/6775-2410-6208-2022-7(17)-01 [In Ukraine]