A novel method for determining the neutral axis position of the asymmetric cross section and its application in the simplified progressive collapse method for damaged ships

• Published in: Ocean engineering Vol. 301; p. 117390
• Main Authors: Zhu, Zhiyao, Ren, Huilong, Incecik, Atilla, Lin, Tong, Li, Chenfeng, Zhou, Xueqian
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.06.2024
• Subjects: Force equilibrium criterion; Force vector equilibrium criterion; Linear equation; Neutral axis; Ultimate strength; Ultimate strength; Linear equation; Force vector equilibrium criterion; Neutral axis; Force equilibrium criterion
• ISSN: 0029-8018; 1873-5258
• DOI: 10.1016/j.oceaneng.2024.117390

Ultimate strength is an important design consideration for the safety of intact or damaged ship structures. The simplified progressive collapse method is a commonly used iterative method to obtain the accurate ultimate strength of ships. Since the accuracy of the neutral axis position directly affects the accuracy of the ultimate strength, the force equilibrium criterion and the force vector equilibrium criterion are adopted to search for the height and angle of the neutral axis, especially for damaged ships. However, the search for the neutral axis position based on the two criteria requires iterative computation which decreases the calculation efficiency. In this paper, the relationship between the results of the iterative process and the neutral axis position is studied, and it is found that the relationship is approximately linear. Then a new iterative method based on the linear equation is proposed to obtain the neutral axis position and is adopted to improve the simplified progressive collapse method. Finally, the new method is used to calculate the neutral axis position of a damaged VLCC. The comparison of the ultimate strength results shows that the improved simplified progressive collapse method based on the linear equation has improved efficiency and good accuracy. •It is found that the results of the equilibrium criterion vary approximately linearly for small movements of neutral axis.•An improved method based on the derived linear equation is proposed for the search of the location of neutral axis.•Comparison of the proposed method with existing methods shows that it is accurate and more computationally efficient.