A team of engineers from RMIT’s Centre for Innovative Structures and Materials utilized biomimicry to develop a super-strong lattice structure that provides enhanced performance compared to traditional honeycomb-based options.
Inspired by the deep-sea sponge, Venus’ flower basket, the design leverages millions of years of evolution to optimize auxeticity, stiffness, and energy absorption. Here’s how this ultra-strong lattice structure could be the key to unlocking next-generation buildings, medical procedures, and much more.
Understanding Auxetic Materials
To grasp the importance of this development, it’s vital to understand the crucial role auxetic materials play in both natural and manmade applications. These materials differ from your traditional items that get squashed when compressed or elongated when stretched.
Instead, auxetic materials exhibit lateral contraction under compression. This characteristic makes them ideal for use in applications where there’s a need to absorb and distribute impact energy effectively. Notably, there are natural versions of auxetic materials like your muscle tendons, and man-made examples, like heart stents that must adjust to vascular pressure demands.
The Evolution of Auxetic Designs
Over the years, there has been a lot of R&D put towards developing the most effective auxetic materials. Some current designs include chiral structures, star-shaped honeycombs, rotating rigid body structures, multi-material auxetics, and re-entrant honeycombs. Of these options, re-entrant hexagonal honeycombs are the most prominent.
The Re-Entrant Hexagonal Honeycomb: A Traditional Approach
The re-entrant hexagonal honeycomb design was bioinspired from the honeycombs found in beehives. It was developed in 1982 and features diagonal ribs that shift inwards under compression, stiffening the design.
Since then, the design has been enhanced with additional struts added to improve performance. However, there are still many drawbacks to the honeycomb layout in terms of flexibility, production costs, and overall performance.
Advancing Lattice Structures: The BLS Study
Recognizing the limitations in this emerging field, a team of Researchers at RMIT University developed a proprietary auxetic design that can outperform its predecessors across the board. The report “Auxetic behavior and energy absorption characteristics of a lattice structure inspired by deep-sea sponge“1 published in Composite Structures highlights how the new design was inspired by the skeletal structure of a deep sponge and is capable of outperforming re-entrant hexagonal honeycombs by 13x.
The Venus’ Flower Basket: Nature’s Blueprint
The deep-sea sponge Euplectella Aspergillum, collectively called Venus’s flower basket, has one of the most durable and unique skeletal structures in all of nature. The sponge features a gridlike skeletal structure composed of glassy elements called spicules that create a square grid.
Source – RMIT Centre for Innovative Structures and Materials
The grid is reinforced by double-lattice struts that give the structure a chessboard look with alternating squares filled in. These open and closed cells provide the animal with unique mechanical properties including unmatched stiffness and high-performance energy absorption.
Constructing a 3D Model of the Bio-Inspired Lattice Structure
The engineers constructed a 3D model to demonstrate their discoveries and test their theories. Their 3D body-centered cubic lattice structure was printed from thermoplastic polyurethane. It included nine square cells arranged in a 3 × 3 grid. Keenly, the team noted that alone, each lattice demonstrated deformation behavior. However, when combined, the material exhibited auxetic actions.
Computational Simulations: Refining the BLS Design
The next step was to utilize data from the testing to create computer simulations. This maneuver allows engineers to improve their testing rate and try more exotic shapes and designs across more tests. They utilized simulations to evaluate the influence of geometric variations.
The data of each material including its auxetic behavior, stiffness, and energy absorption capabilities were documented. Additionally, the team reviewed the impact of structural parameters like the arrangement and thickness of the non-diagonal and double-diagonal bars. The team then fine-tuned the spacing between the double diagonal bars and spacing to achieve optimal performance.
Testing the BLS: Experimental Verification
The researchers tested their new lattice design in various ways. Specifically, a Shimadzu AGS-50kNXD universal tester was utilized to conduct Quasi-static uniaxial compression tests on the 33D-printed BLS-0 and CAS units. The engineers systematically documented all core aspects of the material including auxetic behavior, stiffness, and energy absorption properties.
Impressive Test Results
The tests produced some impressive results. According to the engineers, the BLS outperformed re-entrant hexagonal options across the board. In terms of compression, it beat the original design by 13%. Additionally, it absorbed 10% more energy across a 60% greater strain range.
The BLS showed nearly double the stiffness of traditional tube designs. Also, tt was 3x stronger and showed 4x more ruggedness when compared to its re-entrant honeycomb predecessors. This enhanced mechanical performance comes from a lighter design that utilizes far less material than alternatives.
Key Benefits of the Bio-Inspired Lattice Structure
There are many benefits that make the BLS discovery worthy of note. For one, it provides engineers with a new level of compressive strength and stiffness that enables the creation of more durable items. From homes to cars, this lighter design could enhance the ruggedness of many common items you use daily, a s well as, some of the most highly engineered projects today.
The Role of 3D Printing in BLS Manufacturing
Another major benefit of this design is that it can be 3D printed. This approach allows engineers to customize the layout to meet nearly any application requirements. Also, it provides an opportunity to experiment with other materials in a controlled and easy-to-integrate manner, driving more innovation.
Potential Real-World Applications of BLS
This bio-inspired material could lead to the development of stronger, more resilient structures in industries such as aerospace, automotive, and civil engineering. All of these sectors are in a constant search for materials that are lighter, easier to work with, and exhibit more strength and stiffness.
Now, this team of innovative researchers seeks to inspire a new class of auxetic materials, offering superior mechanical properties such as enhanced energy absorption and structural stiffness.
Engineering Applications: What Comes Next?
Many analysts predict applications could emerge within the next 5 to 10 years, pending further research and development. Here are just some of the potential applications of this technology.
Construction
According to engineers, the building sector will be their main focus. Building and construction materials are expensive with prices increasing sharply over the last few years. This development could revolutionize this sector in a variety of ways.
For one, it would allow builders to create stronger structures that utilize less material. Think of this lattice replacing the steel framing on your house or the beams in a building. The open and closed checkerboard layout and material offer auxetic behavior under compression from a lightweight structure.
Additionally, architects and engineers could create buildings that could be more resilient. Imagine a skyscraper that was designed to reduce vibrations during an earthquake or stiffen up in a particular manner when the wind pushes on it. In this way, BLS could enhance structural engineering capabilities across the market.
Protective Equipment
Another area of interest for BLS is in the protective gear industry. This material will make self-worn protective gear lighter and more resilient. The lattice design will ensure that the lightweight gear can hold up under the harshest conditions and impacts, opening the door for a new level of safety in many of today’s most dangerous sports.
Military
There are several military applications for this material. Imagine next-generation lightweight and super thin bulletproof vests. Engineers could create items like temporary bridges easier, improving both their assembly and transportation. Additionally, it could play a role in creating next-generation vehicles and other equipment that require upgraded stiffness but must meet tight weight constraints.
Think of drones that can fly farther and take more damage, or helmets that can withstand direct hits from high calibers without shattering. All of this and more is possible by utilizing BLS tech.
Medical Applications
The medical field could use this technology to improve several different procedures. For example, implants designed to keep arteries open have to be able to adjust under extreme pressure and last without degrading for years. The new lattice design provides more durability and stiffness when needed, preventing the arteries from closing up and saving lives.
Automotive
There are a lot of different ways that this technology could make your next vehicle safer and more efficient. For one, the updated tube design could replace the steel frame currently in use by many manufacturers. This new design would reduce manufacturing costs and improve strength and durability.
Additionally, this technology could be used to make your ride much smoother. Visualize shocks and other vibration-dampening structures created with these materials. These designs could provide more comfort while not adding to the overall weight of your next EV.
Bio-inspired Lattice Structure (BLS) Researchers
RMIT’s Centre for Innovative Structures and Materials led the study which included Jiaming Ma, Hongru Zhang, Ting-Uei Lee, Hongjia Lu, Yi Min Xie, and Ngoc San Ha as researchers. Now, this team plans to delve into the use of other materials such as steel to test their creation.
The team has also expressed interest in utilizing a combination of materials based on their unique properties to attempt to improve performance further. These experiments will include making the beams and squares out of varying materials that can interact.
Investing in the Material Science Sector
The material science sector has several leading manufacturers that continue to push the tech to new heights. This latest development demonstrates the pace at which innovation in the market occurs. Here is one innovative company that is well-positioned to integrate any breakthroughs in material science to enhance its ROIs and product line.
Hexcel Corporation (HXL -1.18%) entered service in 1948 and is based out of Connecticut. This US-based manufacturer specializes in honeycomb-designed materials. Since its inception, Hexcel has seen great success.
Interestingly, one of the company’s first major government contracts was to develop new-age honeycomb materials for use in radar domes on military aircraft for WWII. Following the end of the war, the company acquired California Reinforced Plastics and Ciba Composites.
In 1995, it acquired the Hercules Composites Products Division. Today, it is recognized as a leading innovator in the field of advanced composite materials for aerospace and industrial applications. The company famously helped design and manufacture the Apollo 11 reentry craft in 1968.
Hexcel Corporation (HXL -1.18%)
Hexcel holds several patents on its research and continues to pour funding into developing next-generation materials that enhance structural integrity, reduce weight, and offer easier manufacturing options.
Currently, Hexcel has 5894 employees and listed $1.90B in revenue in 2024. Its stock is considered a strong “Buy” by most analysts as the firm continues to secure government contracts and support for next-generation technologies. These factors, coupled with the company’s history and positioning make HXL a smart addition to any portfolio.
Latest on Hexcel Corp.
The Future of Bio-Inspired Lattice Structures
When you examine the benefit that bio-inspired lattice structures bring to the market., it’s easy to see that they will one day play a vital role in making electronics lighter, protective gear safer, and your future vehicle more rugged.
Additionally, advancements in 3D printing will make it even easier for engineers to model and create ultra-performance auxetic structures and materials. For now, this team deserves credit for shedding light on how auxetic materials work and how evolution has helped improve their design.
Learn about Other Material Science Breakthroughs Now.
Studies Referenced:
1. Zhu, Y., & Zhang, X. (2024). Auxetic behavior and energy absorption characteristics of a lattice structure. Composite Structures, 300, 116-123. https://doi.org/10.1016/j.compstruct.2024.118835