Structural mechanical properties of circular fish cages determined by finite element analysis and material test

To evaluate the failure risk of the fish cage working at sea, this study analysed the yield and fatigue phenomena of cage floating structure under excessive and long-term wave loads. According to the mechanical tests, the mooring forces of C80 float in normal and extreme sea conditions were 27.41 kN and 86.13 kN, respectively. The S-N curve of HDPE floating material was described by S = -11.93 ln(N) + 29.076. Based on finite element analysis, the C80 failed when the overall horizontal load was 3000 kN or wave height was 23.4 m. The main floating structure showed sheared failure when twisted 5 m for the four-point displacement-load. The failed and fatigued areas were mainly in the mooring points, and the stress concentration mainly occurred at the cracked parts. The C384 cage construction and site test were conducted in the East China Sea. The specifications of the floating structure were enhanced, and the circular curvature and assembling clearances increased. This study could provide guidelines on the structural design and optimisation of the HDPE super large fish cage.

Automated summary

This study evaluates the failure risk of the fish cage by analyzing the yield and fatigue phenomena of the floating structure under wave loads. The results show that the C80 fails when the overall horizontal load reaches 3000 kN or the wave height is 23.4 m. The main failure areas are the mooring points, with stress concentration occurring at the cracked parts. Enhancing the specifications and increasing the circular curvature and assembling clearances can provide guidelines for the structural design and optimization of the HDPE super large fish cage.