PSI - Issue 68

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Procedia Structural Integrity 68 (2025) 1203–1207 Structural Integrity Procedia 00 (2024) 000–000 Structural Integrity Procedia 00 (2024) 000–000

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European Conference on Fracture 2024 Fatigue life assessment of ship propulsion shafting due to torsional and bending vibration Alen Marijancˇevic´ a , Sanjin Braut a, ∗ , Roberto Zˇ igulic´ a , Ante Skoblar a a University of Rijeka, Vukovarska 58, Rijeka 51000, Croatia Abstract In accordance with the Paris Agreement, the International Maritime Organization (IMO) mandates that carbon dioxide emissions be decreased from 2008 levels by at least 40% by 2030 and 70% by 2050. To meet these requirements, there are a number of measures, the most common of which are slow steaming and engine de-rating. As an example of a slow steaming measure, a low speed two-stroke engine with a direct-coupled, fixed-pitch propeller arrangement is considered. Although it is common to study torsional vibrations as the cause of fatigue, bending vibrations due to sail-ing in rough seas were also considered in this analysis. The ship propulsion shaft is modeled with 3D beam FE elements, including torsion and bending. The torsional exci-tation of the engine during normal firing is defined by tangential pressure harmonics. The first two harmonics of the exciting lateral forces and moments, as well as the tor-sional moment, were taken from the propeller. Fig. 1 shows the FEM model of the pro-pulsion shaft and the engine torsional excitation torques. The barred speed range for this propulsion system is between 40 and 51 rpm. After cal-culating vibration torques and lateral forces, a detailed 3D FEM simulation of the inter-mediate shaft is carried out. Low cycle fatigue life is assessed due to torsional vibra-tions, and high cycle fatigue life due to coupled torsional-lateral vibrations. The fatigue life was compared for the conditions MCR, 80% MCR, and the slow steaming condition of 70% MCR. The calculated vibrational stresses were additionally checked according to the guidelines of the International Classification Society (IACS). © 2025 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review under responsibility of ECF24 organizers. Keywords: Fatigue Life; Ship Propulsion Shafting; Torsional Vibration; Bending Vibration European Conference on Fracture 2024 Fatigue life assessment of ship propulsion shafting due to torsional and bending vibration Alen Marijancˇevic´ a , Sanjin Braut a, ∗ , Roberto Zˇ igulic´ a , Ante Skoblar a a University of Rijeka, Vukovarska 58, Rijeka 51000, Croatia Abstract In accordance with the Paris Agreement, the International Maritime Organization (IMO) mandates that carbon dioxide emissions be decreased from 2008 levels by at least 40% by 2030 and 70% by 2050. To meet these requirements, there are a number of measures, the most common of which are slow steaming and engine de-rating. As an example of a slow steaming measure, a low speed two-stroke engine with a direct-coupled, fixed-pitch propeller arrangement is considered. Although it is common to study torsional vibrations as the cause of fatigue, bending vibrations due to sail-ing in rough seas were also considered in this analysis. The ship propulsion shaft is modeled with 3D beam FE elements, including torsion and bending. The torsional exci-tation of the engine during normal firing is defined by tangential pressure harmonics. The first two harmonics of the exciting lateral forces and moments, as well as the tor-sional moment, were taken from the propeller. Fig. 1 shows the FEM model of the pro-pulsion shaft and the engine torsional excitation torques. The barred speed range for this propulsion system is between 40 and 51 rpm. After cal-culating vibration torques and lateral forces, a detailed 3D FEM simulation of the inter-mediate shaft is carried out. Low cycle fatigue life is assessed due to torsional vibra-tions, and high cycle fatigue life due to coupled torsional-lateral vibrations. The fatigue life was compared for the conditions MCR, 80% MCR, and the slow steaming condition of 70% MCR. The calculated vibrational stresses were additionally checked according to the guidelines of the International Classification Society (IACS). © 2025 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review under responsibility of ECF24 organizers. Keywords: Fatigue Life; Ship Propulsion Shafting; Torsional Vibration; Bending Vibration © 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

1. Introduction 1. Introduction

The International Maritime Organization (IMO) has mandated that carbon dioxide emissions be reduced from 2008 levels by at least 40% by 2030 in compliance with the Paris Agreement. There are several ways to achieve these requirements, the most popular being engine de-rating and slow steaming Kim et al. (2017). Older ships are equipped with stronger engines and according to the requirements of the IMO organization, ships must sail at a reduced speed close to the barred speed range (BSR). Newer ships are equipped with reduced power engines that take longer to The International Maritime Organization (IMO) has mandated that carbon dioxide emissions be reduced from 2008 levels by at least 40% by 2030 in compliance with the Paris Agreement. There are several ways to achieve these requirements, the most popular being engine de-rating and slow steaming Kim et al. (2017). Older ships are equipped with stronger engines and according to the requirements of the IMO organization, ships must sail at a reduced speed close to the barred speed range (BSR). Newer ships are equipped with reduced power engines that take longer to

∗ Corresponding author. Tel.: + 385-51-651-502 ; fax: + 385-51-651-416. E-mail address: sanjin.braut@riteh.uniri.hr ∗ Corresponding author. Tel.: + 385-51-651-502 ; fax: + 385-51-651-416. E-mail address: sanjin.braut@riteh.uniri.hr

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.2025.06.188 2210-7843 © 2025 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review under responsibility of ECF24 organizers. 2210-7843 © 2025 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review under responsibility of ECF24 organizers.