Imperial College London

New approach could improve design and damage control of high strength materials

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Results from a recent study in Nature Communications could impact the design and fabrication of high-strength materials.

High strength but lightweight materials are highly sought after for load-bearing applications in the modern world. These applications include automobiles, aerospace, personal protection and civil engineering structures.

Researchers have investigated a new approach to programme the mechanical strength, control damage and increase the performance of lightweight and high-strength materials.

Controlling the strength and damage of high-strength materials 

In 2019, researchers in the Department of Materials chose a unique approach for developing high-strength materials with carefully architected internal structures. The internal structures were constructed in such a way to mimic the microstructure found in crystals to create artificial crystals (coined meta-crystals). The researchers carried out fundamental studies to reveal the origin of the strengthening recently reported for meta-crystals, providing new insights into designing lightweight materials with high strength and controllable damage.

To further their approach, they have now used advanced computer-aided design and simulation to realise the mimicry and analyse the stress responses. 3D printing was also used to fabricate the designed materials.

The mechanical properties of the meta-crystals were examined through mechanical tests and digital image correlation analyses for tracking the localised deformation behaviour during mechanical loading.

A unique insight into meta-crystals

It was found that imitating the polycrystals was highly successful in translating the polygrain boundary hardening found in metallurgy to significantly strengthen architected materials and, increase the isotropy of materials, providing effective ways to design damage-tolerant architected materials with defined local responses. 

"Our obtained insights offer a solid foundation to design new lightweight materials with high strength and spatially controllable properties with high confidence" Mr Chen Liu

This could influence how lightweight materials are designed in the future, with the ability to increase strength, isotropy, and damage-control to specific locations in lightweight materials for loading-bearing and safety-critical applications. 

Mr Chen Liu, Research Assistant in the Department of Materials and lead author said:

"We are pleased to see the inspiration from crystalline materials can be used to engineer the properties of architected materials. This study provides underpinning science to explain the strengthening in polycrystal-like architected materials.

Our obtained insights offer a solid foundation to design new lightweight materials with high strength and spatially controllable properties with high confidence."

Future testing for changing environments 

The researchers will now explore all key strengthening mechanisms found in metallurgy, including multi-phase engineering and precipitation hardening. 

The aim is to test the key performance of meta crystals under different loading conditions, such as multiaxial, tension or cyclic loading, to improve the design of materials for load-bearing and safety-critical conditions.

From this testing phase, researchers aim to create lightweight, high-strength materials that are more responsive to changing environments using meta-crystals.

The full paper is now available to read in Nature Communications.

Reporters

Chen Liu

Chen Liu
Department of Materials

Kayleigh Brewer

Kayleigh Brewer
Department of Materials

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