Researchers at RMIT University have developed a new material inspired by the deep-sea sponge Venus’ flower basket, demonstrating compressive strength and stiffness that could advance architectural and product design.
The breakthrough comes from a double lattice design mimicking the intricate skeleton of the Pacific Ocean-dwelling sponge, the university said in a news release.
According to lead author Dr Jiaming Ma, extensive testing and optimisation have shown the structure’s unique combination of strength, stiffness, and auxetic behaviour—the ability to contract when compressed.
“While most materials get thinner when stretched or fatter when squashed, like rubber, auxetics do the opposite,” Ma explained. “Auxetics can absorb and distribute impact energy effectively, making them extremely useful.”
Natural auxetic materials include tendons and cat skin, while synthetic versions are already used in medical applications such as heart and vascular stents.
However, conventional auxetic materials tend to have low stiffness and limited energy absorption, restricting their practical use. The RMIT team’s nature-inspired double lattice design addresses these limitations.
“Each lattice on its own has traditional deformation behaviour, but if you combine them as nature does in the deep-sea sponge, then it regulates itself, holds its form, and outperforms similar materials by quite a significant margin,” Ma said.
Published in Composite Structures, the study found that, with the same material usage, the new lattice design is 13 times stiffer than existing auxetic materials based on re-entrant honeycomb structures.
Additionally, it can absorb 10 per cent more energy while maintaining its auxetic properties over a 60% greater strain range compared to current designs.
Dr Ngoc San Ha said these properties open new possibilities for application across multiple industries.
“This bioinspired auxetic lattice provides the most solid foundation yet for us to develop next-generation sustainable building materials,” Ha said.
“Our auxetic metamaterial with high stiffness and energy absorption could offer significant benefits across sectors, from construction materials to protective equipment, sports gear, and medical applications.”
Potential applications include using the structure as a steel building frame, reducing the amount of steel and concrete required while maintaining structural integrity.
The material could also be adapted for lightweight sports protective gear, bulletproof vests, and medical implants.
Honorary Professor Mike Xie emphasised the broader implications of biomimicry in engineering.
“Not only does biomimicry create beautiful and elegant designs like this one, but it also creates smart designs that have been optimised through millions of years of evolution that we can learn from,” Xie said.
The researchers at RMIT’s Centre for Innovative Structures and Materials have tested the design through computer simulations and lab experiments on a 3D-printed thermoplastic polyurethane sample.
Next, they plan to produce steel versions and integrate them with concrete and rammed earth construction techniques.
“While this design could have promising applications in sports equipment, PPE, and medical applications, our main focus is on the building and construction aspect,” Ma said.
“We’re developing a more sustainable building material by using our design’s unique combination of outstanding auxeticity, stiffness, and energy absorption to reduce steel and cement usage in construction.”
Ma also highlighted the design’s potential in earthquake-resistant structures, where its auxetic and energy-absorbing properties could help dampen vibrations.
The team is further exploring how machine learning algorithms could optimise the design, potentially leading to the creation of programmable materials.
The study, Auxetic behavior and energy absorption characteristics of a lattice structure inspired by deep-sea sponge, is published in Composite Structures (DOI: 10.1016/j.compstruct.2024.118835).
