Chepil O. Methodology of local energy approach for durability prediction of structural elements of power equipment under their creep and hydrogenation

Українська версія

Thesis for the degree of Doctor of Science (DSc)

State registration number

0524U000309

Applicant for

Specialization

  • 01.02.04 - Механіка деформівного твердого тіла

25-09-2024

Specialized Academic Board

Д 35.226.02

Physico-Mechanical Institute named after GV Karpenko of the National Academy of Sciences of Ukraine

Essay

The dissertation presents a methodology for assessing the impact of a hydrogen-containing environment on the long-term strength of structural elements of thermal power equipment under creep conditions. The methodology combines a computational technique for determining deformation energy and damage accumulation kinetics, considering material hydrogenation under high-temperature creep, a local energy fracture criterion, and an experimental method for determining fracture energy. To ensure high reliability in constructing damage accumulation curves in the material, a phenomenological generalized model was developed for the first time, accounting for the impact of hydrogenation on microdefect accumulation during high-temperature elastic-plastic deformation. For the first time, the deformation energy of an entire structural element under operating conditions and complex geometry, as well as local stress concentration volumes, was determined and assessed using the proposed methodology. Algorithms and programs for calculating the stress-strain state and hydrogen concentrations using the finite element method were developed and subsequently used to determine deformation energy. Copyright certificates were obtained for the developed programs. The proposed methodologies were tested and demonstrated satisfactory agreement with experimental and calculated literature data. Using the presented methodology for predicting the durability of structural elements of power equipment under creep and hydrogenation conditions, the residual life of thermal power equipment elements was determined under operating conditions, considering an aggressive environment, complex geometry, and prior material deformation.

Research papers

1. Hembara О.V., Chepil O.Y., Hembara N.Т. Influence of the Parameters of Discretization on the Accuracy of Numerical Solution of the Three-Dimensional Problem of Hydrogen Diffusion // Materials Science. – 2016.–52(2). P. 280–286

2. Hembara О.V., Chepil O.Y., Hembara Т.V. Application of the Energy Approach to the Evaluation of the Serviceability of the Drum of a Steam Boiler Subjected to Thermal Cycling and Hydrogenation

3. Fabing Qin, Hembara О.V., Chepil O.Y. Modeling of the influence of hydrogen on the bearing ability of elements of the power-generating equipment under the conditions of temperature creep // Materials Science. ‒ 2018. ‒ 53, № 4. ‒ P. 532–540

4. Chang Shu, Hembara О.V., Chepil O.Y. Calculation of the Lifetime of Heat and Power Equipment Under Long-Term Static Loading, High Temperature, and the Action of Hydrogen// Materials Science. ‒ 2018. ‒ T. 54, № 1. ‒ P. 107–114.

5. Jiang Qiongqin, Hembara О.V., Chepil O.Y. Modeling of the influence of hydrogen on the accumulation of defects in steels under high-temperature creep // Materials science. – 2019.–55, №2. –P.251–259

6. Chepil O.Y., Shtoiko I. P. Distribution of hydrogen concentration in a compact specimen under the conditions of electrolytic hydrogenation // Materials science. – 2019.–55, №3. –P.392–396

7. The energy approach to the evaluation of hydrogen effect on the damage accumulation/ Ya. Ivanytskyi, Ye. Kharchenko, O. Hembara, O. Chepil, Ya. Sapuzhak, N. Hembara // Procedia Structural Integrity. – 2019. – 16. – С. 126–133. DOI: 10.1016/j.prostr.2019.07.031

8. Influence of temperature and hydrogen on fatigue fracture of 10kh15n27t3v2mr steel/ O. Hembara, O. Chepil, T. Hembara, V. Mochulskyi, Ya. Sapuzhak// Journal of Theoretical and Applied Mechanics. –2020. – 58, 1. – Р. 3–15. DOI: 10.15632/jtam-pl/115214

9. Zhigang Liu, Chepil O.Y., Sapuzhak Ya. І. Mathematical Modeling of Damage Accumulation under the Conditions of Creep and Corrosion Cracking of Structural Materials // Materials Science. – 2021.–56, №6. –P.764–770

10. Ming W., Hembara O.V., Chepil O.Y. Computer Modeling of the Influence of Hydrogenation on the Durability of Pipe Elements // Materials Science. – 2021.–57, №1. – P.128–134

11. Hembara O.V., Chepil O.Y. Modeling of the Deformation of Structural Elements Under the Conditions of Creep, Corrosion Cracking, and Hydrogenation // Materials Science. – 2022. – 57, №4. – P.557–561

12. Influence of Hydrogen on the Fracture Resistance of Pre-Strained Steam Generator Steel 22K/ Maciej Dutkiewicz, Oksana Hembara, Yaroslav Ivanytskyi, Mykola Hvozdiuk, Olha Chepil, Mykhailo Hrynenko, Nazar Hembara.// Materials. – 2022. – 15 (19). – 6596

13. Evaluation of the Influence of the Hydrogenation of Metal on the Durability of Heat-Exchanger Tubes of Steam Generators/ O.V. Hembara, О.Y. Chepil, N.Т. Hembara, А.М. Syrotyuk // Materials Science. – 2022. – 58, №3. –P.325–330

14. A New Energy Approach to Predicting Fracture Resistance in Metals/ M. Dutkiewicz, O. Hembara, O. Chepil, M. Hrynenko, T. Hembara // Materials. – 2023. – 16 (4). – P. 1566

15. Assessing of the Life Time of a Shaft with a Crack in Hydrogen/ O.V. Hembara, O.M. Holian, O.Y. Chepil, V.M. Paliukh, Y.I. Sapuzhak, I.M. Soviak // Materials Science. – 2023. – 59, №2. – P.191–197

16. Hembara O., Syrotyuk A., Chepil O., Sapuzhak Y., Hembara N. Evaluation of Increased Local Hydrogen Concentration in the Vicinity of Various Types of Defects in Low-Alloyed// Steels. Procedia Structural Integrity. – 2024.– 59, –P.190-197.

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