A finite element modeling technique for an aquaculture net with laboratory measurement comparisons

The escape of fish from an aquaculture facility can be considered a threat to wild populations. Openings in the containment net can occur from stresses induced by inadequate attachments, abrasion or fish bite. The objective of this work involves the development of a net finite element model (FEM) with focus on a representation of the Raschel net structure. An approach is taken with a combination of FEM simulations and laboratory tests. Material and geometric properties of a net were obtained from peer-reviewed literature, standards and complemented with tensile testing. FEM simulations of a net pen system were performed under operational conditions to approximate tensions within the net. The distribution of tension in the net panel was considered a two-dimensional problem dependent on mesh construction. Elongation experiments were conducted with orthogonal loading to measure planar deflections. A FEM of the net panel was then built with a focus on the net structure, loaded and results compared with laboratory data. The results showed that the construction details influence loaded deflections. Next, holes were made in the model by removing trusses representing twine sections, loaded and strain values compared with measurements obtained from laboratory tests with the same holes in the net panel.