Damage Monitoring Method for Deep-Sea Net Cage Rope Structure Based on Tension Signal

The net system is an important component of the deep-sea net cages. As the bone structure of the net system, the rope structure bears the main hydrodynamic load of the net system, making the monitoring its health status essential. Aiming at the online damage monitoring of the rope structure, a finite element numerical model of the rope structure is developed, and the mechanical properties of the rope structure under intact and damaged conditions are compared and analyzed. The results show that when the rope is damaged, the end tension load of the damaged rope decreases sharply, while the end tension load of the adjacent rope increases. Based on the characteristics of these sudden tension changes and the influence of the damaged rope on the load of undamaged rope, three damage identification parameters are defined as the tension correlation coefficient, the total influence value, and the tension variation coefficient of the rope structure. Additionly, an online damage monitoring method based on rope tension signal is proposed. This method identifies the damaged rope by detecting an extremum step in the tension variation coefficient, and determines the specific damaged position by analyzing the proportion relationship between the tension change coefficient and the distance from the end to the damaged position. The research provides a reliable method for online monitoring of rope structure damage for the healthy operation and maintenance of deep-sea net cages.