Citation: Lee, D.-Y.; Jo, J.-S.; Nyongesa, A.J.; Lee, W.-J. Fatigue Analysis of a 40 ft LNG ISO Tank Container. Materials 2023, 16, 428. https://doi.org/10.3390/ma 16010428 Academic Editor: Alexey Borovkov Received: 9 November 2022 Revised: 21 December 2022 Accepted: 25 December 2022 Published: 2 January 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). materials Article Fatigue Analysis of a 40 ft LNG ISO Tank Container Du-Yong Lee 1,2 , Jae-Sang Jo 1,3 , Antony John Nyongesa 2,4 and Won-Ju Lee 4,5, * 1 Korea Marine Equipment Research Institute, Busan 46754, Republic of Korea 2 Division of Marine Engineering, Korea Maritime and Ocean University, Busan 49112, Republic of Korea 3 Department of Mechanical IT Convergence Engineering, Korea Maritime and Ocean University, Busan 49112, Republic of Korea 4 Interdisciplinary Major of Maritime AI Convergence, Korea Maritime and Ocean University, Busan 49112, Republic of Korea 5 Division of Marine System Engineering, Korea Maritime and Ocean University, Busan 49112, Republic of Korea * Correspondence: skywonju@kmou.ac.kr; Tel.: +82-51-410-4262 Abstract: The demand for Liquefied natural gas (LNG) has rapidly increased over the past few years. This is because of increasingly stringent environmental regulations to curb harmful emissions from fossil fuels. LNG is one of the clean energy sources that has attracted a great deal of research. In the Republic of Korea, the use of LNG has been implemented in various sectors, including public transport buses, domestic applications, power generation, and in huge marine engines. Therefore, a proper, flexible, and safe transport system should be put in place to meet the high demand. In this work, finite element analysis (FEA) was performed on a domestically developed 40 ft ISO LNG tank using Ansys Mechanical software under low- and high-cycle conditions. The results showed that the fatigue damage factor for all the test cases was much lower than 1. The maximum principal stress generated in the 40 ft LNG ISO tank container did not exceed the yield strength of the calculated material (carbon steel). Maximum principal stress of 123.2 MPa and 107.61 MPa was obtained with low-cycle and high-cycle analysis, respectively, which is 50.28% less than the yield strength of carbon steel. The total number of cycles was greater than the total number of design cycles, and the 40 ft LNG ISO tank container was satisfied with a fatigue life of 20 years. Keywords: LNG; finite element analysis (FEA); ISO tank; Ansys Mechanical 1. Introduction LNG fuel has attracted a great deal of research attention as a potential source of clean energy. Natural gas, which is obtained from the boiling of vapor of LNG, is mainly made up of methane (CH4) which is the simplest hydrocarbon compound [1]. It has only one carbon atom in its chemical structure. Research on LNG usage has revealed a significant reduction in carbon-based exhaust gas emissions, especially in internal (IC) combustion engines [2–5]. With increasingly tight environmental regulations, LNG fuel is a potential clean fossil fuel. In the Republic of Korea, LNG usage has been implemented in various sectors, including city gas pipelines supplied to each household and public transport buses. Gradually, LNG is being used in various industries such as power generation and shipbuilding. In recent news, the Republic of Korea also plans to replace the existing ships with LNG-fueled ships [6]. Therefore, SK Gas, which is the largest gas producer in the country, has invested heavily in the expansion of LNG infrastructure. Compared with diesel or heavy fuel oil, LNG has a higher lower calorific value, and therefore an IC engine operating at the same power output will require a smaller amount of LNG fuel [1]. As the demand for LNG increases, research and development for a method of supplying LNG is also being actively carried out [7–13]. The method of supplying NG (natural gas) to consumers can be generally divided into ‘NG supply through the piping network’, ‘LNG supply through tank lorry’, and ‘LNG supply through tank container’. Materials 2023, 16, 428. https://doi.org/10.3390/ma16010428 https://www.mdpi.com/journal/materials