Sustainable Marine Structures

The proposed bio-inspired meta-composite lattice platform (BMCLP) comprises topology-optimized octet-truss lattices with bio-epoxy composite skins reinforced with flax fibre, geometrically based on skeletal architectures of Hexactinellida sponges. A coupled multi-physics framework was developed for a 15 MW floating wind turbine system, integrating finite-element structural analysis, potential-flow hydrodynamics with equivalent Morison calibration for porous lattice members, spectral fatigue assessment with conservative S-N knock-downs for natural fibre composites, Fickian seawater degradation modelling, and a streamlined life cycle assessment (LCA). The BMCLP reduced structural mass by 68.5% while preserving a comparable global stiffness to the steel OC4-DeepCwind benchmark. Hydrodynamic validation against published semi-submersible response amplitude operator (RAO) data showed an 18% reduction in pitch response amplitude under extreme sea state conditions due to wave energy dissipation through the porous lattice; this advantage decreased to 10% under 50 mm marine fouling and 5% under 100 mm heavy fouling. Spectral fatigue analysis using a Joint North Sea Wave Project (JONSWAP) spectrum indicated that the pontoon-to-column joint governed fatigue life, with a 25-year damage index well below unity. Fickian diffusion modelling predicted 78.8% residual compressive strength at 25 years. The LCA demonstrated a 77.6% reduction in global warming potential (GWP) over a 25-year service life, mainly due to bio-based material substitution, avoided steel production, and reduced additive-manufacturing waste. The research links biomimetic structural design, validated multi-physics performance, and circular economy principles, providing a reproducible methodology for low-carbon floating offshore infrastructure.