Level 1 — Absolute Beginner
Engineers are people who build and design things. Engineers at RMIT University in Melbourne, Australia worked with engineers in France. They made a new metal material. It can float on water.
The material is called titanium. Titanium is a strong, light metal. The engineers made small tubes of titanium and connected them together. This is called a lattice. A lattice looks like a strong net or mesh.
Most light metal like this sinks in water. Water gets inside the small holes and pulls it down. The engineers put foam inside the tiny tubes. Now the material can float, even when it is cracked or broken.
The engineers tested the material in water for more than two months. It kept floating. This new material could be used for floating docks and ocean sensors in the future.
- engineer
- A person who designs and builds things, like machines or materials.
- float
- To stay on top of water instead of sinking.
- material
- A substance used to make something, like metal, wood, or plastic.
- titanium
- A strong, light silver colored metal.
- lattice
- A frame made of connected pieces, like a strong net or mesh.
- metal
- A hard, shiny material like iron, steel, or titanium.
- crack
- A break or line of damage in something.
- foam
- A soft, light material full of tiny air pockets.
Level 2 — Elementary
Engineers at RMIT University in Melbourne, Australia, worked together with engineers at the Conservatoire National des Arts et Metiers in France. Together, they built a new kind of material: a titanium structure that keeps floating even after it is badly damaged.
The material is a lattice, a lightweight framework made from a 3D printed pattern of hollow, connected titanium struts. Normally, a metal lattice this light would sink once water gets into its open spaces, because it is less than one tenth as dense as water.
To solve this problem, the engineers filled only the hollow struts, not the whole lattice, with polyurethane foam. Water can still flow freely through the outer open spaces of the lattice, but the structure itself stays buoyant, meaning it keeps floating, even after cracking.
In tests, pieces of the material floated in freshwater for more than two months and also survived exposure to seawater. It performed better than the stainless steel and high density plastic that are normally used in things like jetties, buoys, and floating sensors.
- lattice
- A lightweight framework built from a repeated pattern of connected pieces.
- struts
- The hollow, connected pieces that make up the lattice.
- buoyant
- Able to float instead of sinking.
- polyurethane foam
- A light, spongy material used to fill the struts.
- density
- How heavy something is compared to its size.
- seawater
- Salty water from the ocean.
- jetty
- A structure, like a dock, that reaches out into water.
- sensor
- A device that detects and measures things, like temperature or motion.
Level 3 — Intermediate
Researchers at RMIT University in Melbourne, Australia, collaborating with the Conservatoire National des Arts et Metiers in France, have developed what they describe as the world's first floating metal hybrid lattice metamaterial, a titanium structure engineered to remain buoyant even after sustaining significant damage.
The material consists of a 3D printed lattice built from hollow, interconnected titanium struts, forming a lightweight open framework with a density less than one tenth that of water. Conventionally, metal lattices this light lose their buoyancy quickly, since water seeps into the open, interconnected internal spaces and drags the structure down.
The team's key innovation was selective infill: rather than sealing the entire lattice, they filled only the hollow struts themselves with polyurethane foam. This allows water to move freely through the lattice's outer open architecture while the internal foam keeps the structure buoyant, a property that persists even after cracking or other structural damage.
In testing led by RMIT's Centre for Additive Manufacturing, sample sections floated in freshwater for more than two months and also withstood exposure to seawater, outperforming the stainless steel and high density plastic conventionally used in marine infrastructure such as jetties, buoys, and floating sensors. Metal is typically stronger and more durable than these plastics, but has historically been too heavy or too prone to sinking once punctured to serve in such applications.
- metamaterial
- An engineered material with properties that come from its structure, not just what it is made of.
- buoyancy
- The ability of an object to float in a liquid.
- infill
- Material used to fill an empty space or cavity within a structure.
- interconnected
- Linked or joined together throughout a structure.
- durable
- Able to withstand wear and damage over a long time.
- marine infrastructure
- Built structures used in or near the ocean, such as docks and buoys.
- conventional
- Traditional or commonly used, in the usual way.
- structural damage
- Harm to the physical framework of an object, such as cracks or breaks.
Level 4 — Advanced
Engineers at RMIT University in Melbourne, Australia, working in collaboration with France's Conservatoire National des Arts et Metiers, have reported what they characterize as the first floating metal hybrid lattice metamaterial, a titanium architecture engineered to retain buoyancy even after incurring substantial structural damage.
The structure is a 3D printed lattice of hollow, interconnected titanium struts, an open framework whose density falls below one tenth that of water. Such lattices have conventionally been unable to sustain long term buoyancy, since their open, interconnected internal geometry allows water to infiltrate freely, eventually overwhelming any initial flotation.
The researchers' resolution to this trade off was architectural rather than material: rather than sealing the lattice's exterior, or increasing wall thickness at the expense of weight, they confined a polyurethane foam infill to the interior of the struts themselves. This preserves the lattice's permeable outer geometry, allowing water to pass through freely, while the enclosed foam sustains buoyancy independent of surface cracking or other localized damage.
Testing overseen by RMIT's Centre for Additive Manufacturing found that sample sections floated in freshwater for more than two months and withstood seawater exposure as well, exceeding the performance of the stainless steel and high density plastics that presently dominate marine infrastructure such as jetties, buoys, and floating sensors. The implication is notable: metal has long offered superior strength and longevity over these plastics, yet its practical use in floating marine hardware has been constrained by weight and by a tendency to sink once punctured, a limitation this hybrid architecture appears designed specifically to address.
- architecture
- The overall structural design of a system or object.
- trade off
- A balance between two desirable but competing outcomes.
- permeable
- Allowing liquids or gases to pass through.
- infiltrate
- To pass into or through something gradually.
- localized
- Confined to a particular, limited area rather than spread throughout.
- dominate
- To be the most common or influential thing in a category.
- hybrid
- Made by combining two different elements or approaches.
- longevity
- The length of time something lasts or remains in use.
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