Hinge joint damage identification method of soft yoke mooring system based on multibody dynamic modeling and structural monitoring data

• Published in: Marine structures 2020-11, Vol.74 (C), p.102808, Article 102808
• Main Authors: Lyu, Baicheng, Guo, Chongchong, Wu, Wenhua, Feng, Jiaguo, Yao, Weian, Yue, Qianjin
• Format: Article
• Language: English
• Subjects: Coefficient of friction; Damage detection; Damage identification; Dynamic models; Friction; Genetic algorithm; Genetic algorithms; Identification; Identification methods; Joints (timber); Model testing; Monitoring; Mooring; Mooring systems; Multibody dynamic modeling; Multibody systems; Prototypes; Scale models; Shallow water; Soft yoke mooring system (SYMs); Thrust bearings; Universal joints; Warning systems
• ISSN: 0951-8339; 1873-4170
• DOI: 10.1016/j.marstruc.2020.102808

Soft yoke mooring system (SYMs) is a single-point mooring system used in shallow water oil and gas development. In general, SYMs consists of mooring framework support, mooring legs, yoke, and single-point turret and it forms a multibody dynamic system with 13 hinge joint structures such as universal joints and thrust bearings. The hinge joint is one of the key components of SYMs; therefore, it is necessary to accurately evaluate the operating behavior of the hinge joints. In this study, real-time damage identification is conducted based on the multibody dynamic features of the SYMs. First, a long-term monitoring strategy for the prototype application is developed based on the multibody governing equations of the SYMs. The motion behaviors and stress state of the hinge joints and bodies are calculated using prototype monitoring data. A hinge joint damage identification based on the virtual moment is proposed by considering the changes in the friction coefficient in the damage state. The virtual moment method is used to transform the damage identification problem of the SYMs into a problem of seeking the optimal solution to the dynamics identification function. Genetic algorithm (GA) is implemented to seek the optimal solution of the friction coefficient of each hinge joint. A large-scale model testing system of the SYMs is established to perform the damage identification of the bottom hinge joints of the SYMs. The results show that the proposed method can effectively identify the damage degree and position of the hinge joints of the SYMs and provide a real-time warning system for the in-service operation of the SYMs. •A novel damage identification method for in-service soft yoke mooring system has been proposed.•Damage identification problem is transformed into a optimization problem of multibody dynamics equations.•Numerical modeling and a large-scale model test are conducted to assess the feasibility of the damage identification method.