Material mechanics properties and critical analyses of fish farm netting and trusses

Abstract

Fish farms face the risk of aquaculture failure due to prolonged operation and the excessive loads caused by typhoons. Aging tests conducted for this study using salt spray, humid heat, and xenon lamps confirm that netting performance significantly declines compared to that of unused nets. The seawater-exposed portion of the netting in the dry–wet separation area is especially susceptible to damage. After three years of natural aging, the netting retains 48% of its original strength, and its elongation at break decreases from 90% to 32%. Under a standard load of 20 N, the equivalent wire model's maximum wear length is 205 m. The fishing net is prone to wear because of sliding friction with the truss. The net opening may fracture when loaded with 1000 N, with a maximum stress of 36.40 MPa at the corners. The netting's fatigue life decreases sharply when the vibration force exceeds 60% of its maximum strength. Moreover, risk analysis shows that fish farms with single-point mooring can successfully withstand a tension of 1256.72 kN during super-typhoons. In redesigned models, buoyancy tanks decrease current resistance, and trapezoidal fishing nets with an increasing slope along the truss column effectively reduce wear.