Nonlinear hydroelastic analysis of an aquaculture fish cage in irregular waves

•Nonlinear hydroelastic responses of fish cages in irregular waves are studied.•Modal superposition method was used to analyze the numerical results.•Instantaneous buoyancy forces on floating collar were considered.•The volume deduction, mooring line forces were investigated.

In this paper, an investigation of the nonlinear hydroelastic response of a deep-water gravity aquaculture fish cage in irregular waves is described. Beam elements, truss elements, and nonlinear springs were used to simulate the motion and deformation of the floating collar, the net, and the mooring lines, respectively, in a finite element model, where large-deformation geometric nonlinearities were also taken into account. Irregular waves were simulated by choosing a suitable wave spectrum, and the nonlinearities of the wave loads were also considered. The instantaneous buoyancy forces on the floating collar were considered by use of the “distributed beam method.” The dynamic displacement response of the collar in irregular waves, the modal contribution from each mode shape, the reduction of the fish cage volume, and the mooring-line forces were studied.