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

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 automobiles, aerospace, personal protection and civil engineering structures. 

3D printing is a common method for manufacturing engineering components in these industries. These printed components feature lattice structures—arrangements of material resembling a grid characterised by repeating nodes and connecting struts, contributing to their lightweight nature. However, the drawback of traditional lattice structures is their tendency to undergo catastrophic failure and cracking, imposing limitations on their utilization.

In 2019, experts in the Department of Materials investigated a unique approach for developing high-strength materials with carefully architected 3D printed internal structures. Scientists found that, when loaded with weight, the new material — which they dub a ‘meta-crystal’ — is far stronger and more damage-tolerant than conventional lattice structures. Researchers also discovered the strength of meta-crystals increased when the size of each latticen within the structure is reduced.

Building upon this research, researchers have now further developed lightweight and high-strength materials that can be programmed for mechanical strength, control damage, and increase performance.

Controlling the strength and damage of high-strength materials 

In a new paper published in Nature Communications, scientists have now used advanced computer-aided design and simulation techniques to apply mimicry and analyze stress responses to the material. 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.

Researchers found that imitating the polycrystals was highly successful in translating the polygrain boundary hardening found in metallurgy to strengthen architected materials and increase the isotropy of materials.

"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

These findings shape the future design of lightweight materials, with the ability to increase strength, isotropy, and damage control to specific locations in lightweight materials. This could have applications involving load-bearing and safety-critical scenarios - leading to the development of more resilient and reliable structures in automobiles, aerospace, personal protection and civil engineering structures. 

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 

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.