RMIT develops buoyant PBF-LB titanium lattice for marine applications
Researchers at RMIT University, in Melbourne, Australia, have developed a buoyant titanium structure produced using laser beam Powder Bed Fusion (PBF-LB) that is intended to retain buoyancy even when damaged.
The structure combines additively manufactured Ti-6Al-4V hollow-strut lattices with polyurethane foam filling the internal channels. The approach is intended to combine the strength and corrosion resistance of titanium with a lightweight architecture capable of maintaining buoyancy following localised structural damage.
The researchers designed the lattice with hollow struts rather than relying on sealed external cavities for buoyancy. Polyurethane foam is introduced inside the interconnected hollow channels, providing distributed buoyancy throughout the structure. According to the researchers, this means cracking or damage to one area does not necessarily allow water ingress to compromise the complete structure.
Mechanical testing showed that the architecture could remain buoyant following significant damage, including the failure of an entire lattice layer. At an equivalent overall density, the titanium-polyurethane lattice was reported to be around 70% stronger than stainless steel or high-density polyethylene (HDPE).
The researchers also investigated its performance in a marine environment. Following two weeks of exposure to natural seawater, the material reportedly showed approximately 0.15% mass loss and less than a 1% reduction in strength.
As part of the study, the team produced a prototype buoy incorporating the PBF-LB titanium structure and demonstrated it in turbulent seawater. The researchers see potential applications for the technology in marine structures and offshore infrastructure, particularly where conventional buoyant materials may be vulnerable to damage or degradation.
The combination of PBF-LB and lattice design also allows the geometry, wall thickness and distribution of material to be tailored to different structural requirements. The researchers state that the approach could therefore be adapted for applications ranging from floating platforms and offshore energy infrastructure to deep-sea equipment.
Further work is planned to manufacture larger demonstration components and assess the structures under longer-term, realistic marine and deep-sea conditions. The team is also seeking industry partners to support scale-up and application development.
The study ‘Breaking the surface: buoyant metal–polymer open–cell hybrid lattice metamaterials’ was published in Advanced Materials.
