PSI - Issue 68

ScienceDirect Structural Integrity Procedia 00 (2025) 000–000 Structural Integrity Procedia 00 (2025) 000–000 Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Available online at www.sciencedirect.com ScienceDirect

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

Procedia Structural Integrity 68 (2025) 559–565

European Conference on Fracture 2024 Role of high-frequency loads in hydraulic unit destruction Evgeniia Georgievskaia a, * a «Center of design and technological innovation» LLC, Nab. reki Karpovki, d. 5, str. YA, Saint-Petersburg, 197376, Russia Abstract High-frequency (HF) hydraulic loads go along with hydraulic unit’s (HU) operation throughout the operating range and cause stress pulsations in its components. The amplitudes of these pulsations are significantly lower than the amplitudes caused by low frequency (LF) loads. Therefore, the lifetime estimation of hydropower units often ignores HF loads. This leads to overestimated lifetime expectations and to hydraulic unit components’ failures long before the predicted occurrence of hazardous cracks. Hydraulic unit lifetime estimation approach presented below relies upon fracture mechanics methods applied to lifetime determining unit components and takes into account the combined effect of LF and HF loads. At first the lifetime estimation takes place in terms of crack length. Then the residual lifetime determined is the amount of operating hours left (taking into account the particular unit’s application). After a long period of operation, HF loads manifest themselves when the material damage reaches a certain critical level as well as the threshold for stress intensity factor (SIF) decreases. The proposed approach can be utilized as a convenient and effective tool to determine time for necessary repairs or replacement of worn components. © 2025 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) European Conference on Fracture 2024 Role of high-frequency loads in hydraulic unit destruction Evgeniia Georgievskaia a, * a «Center of design and technological innovation» LLC, Nab. reki Karpovki, d. 5, str. YA, Saint-Petersburg, 197376, Russia Abstract High-frequency (HF) hydraulic loads go along with hydraulic unit’s (HU) operation throughout the operating range and cause stress pulsations in its components. The amplitudes of these pulsations are significantly lower than the amplitudes caused by low frequency (LF) loads. Therefore, the lifetime estimation of hydropower units often ignores HF loads. This leads to overestimated lifetime expectations and to hydraulic unit components’ failures long before the predicted occurrence of hazardous cracks. Hydraulic unit lifetime estimation approach presented below relies upon fracture mechanics methods applied to lifetime determining unit components and takes into account the combined effect of LF and HF loads. At first the lifetime estimation takes place in terms of crack length. Then the residual lifetime determined is the amount of operating hours left (taking into account the particular unit’s application). After a long period of operation, HF loads manifest themselves when the material damage reaches a certain critical level as well as the threshold for stress intensity factor (SIF) decreases. The proposed approach can be utilized as a convenient and effective tool to determine time for necessary repairs or replacement of worn components. © 2025 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 ECF24 organizers Keywords: high-frequency loads; hydraulic unit; failure; crack; 1. Introduction Hydropower is one of the most environmentally friendly ways to obtain energy. Hydropower plays an important role in electricity production worldwide, as noted by IHA (2023), Vagnoni et al. (2023), Jamali et al. (2022): • HPPs produce approximately 17% of total global electricity consumption; © 2025 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 ECF24 organizers Peer-review under responsibility of ECF24 organizers Keywords: high-frequency loads; hydraulic unit; failure; crack; 1. Introduction Hydropower is one of the most environmentally friendly ways to obtain energy. Hydropower plays an important role in electricity production worldwide, as noted by IHA (2023), Vagnoni et al. (2023), Jamali et al. (2022): • HPPs produce approximately 17% of total global electricity consumption;

* Corresponding author. Tel.: +7-921-971-64-43. E-mail address: sciencedir@cdti.ru * Corresponding author. Tel.: +7-921-971-64-43. E-mail address: sciencedir@cdti.ru

2452-3216 © 2025 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 ECF24 organizers 2452-3216 © 2025 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 ECF24 organizers

2452-3216 © 2025 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 ECF24 organizers 10.1016/j.prostr.2025.06.097