Foam-filled titanium lattice remains buoyant after structural damage

RMIT University researchers created a 3D-printed titanium lattice that floated in fresh water and seawater despite cracks, fractured connections and the loss of an entire lattice layer. The design uses hollow Ti-6Al-4V beams filled with closed-cell polyurethane foam, which blocks water from spreading through damaged internal channels while the metal carries structural loads. Samples remained submerged in fresh water for more than two months, and a prototype buoy floated in turbulent natural seawater. The material lost 0.15% of its mass and less than 1% of its strength during a two-week seawater test. Larger-scale construction and long-term marine durability remain unproven.