Biomimicry & lightweight design:
a winning bet
The challenge is almost universal. It concerns all industries: to produce better, to rationalise the use of materials and to reduce the environmental impact of a product or component, we must be able to think of intelligent structures, best combining the weight/resistence ratio.
This challenge is particularly exacerbated in aeronautics and automotive industries, that are in the spotlight and have to reduce the consumption of their products as well as their CO2 emissions. An objective which sometimes seems contradictory in relation to market trends, in particular because of the complexity of the systems: in Europe, the weight of vehicles has increased by 60% since 1960.
How can we design structures, or shape and use materials that are lighter and just as robust? Biomimicry is an ideal response as it is the champion of lightweight design and one that has already proven itself in this area!
©Airbus | P.Masclet / master films
A specialist in the field, Bioxegy explains why and how biomimicry is an essential design tool in terms of lightweight design and provides you with a selection of particularly evocative examples.
Nature, champion of lightness and minimal effort
To hunt, feed or defend themselves, to cope with environmental hazards, living species must balance mobility, robustness, lightness and flexibility as best they can.
Evolution has also equipped them with the best anatomical principles to rationalise energy and material consumption.
Their organisation is therefore based on a design which must guarantee the best structural properties while ensuring material sobriety.
Nothing is left to chance. Nature has developped particularly intelligent stratagems or materials and unlimited know-how to optimise the relationship between mass and robustness.
The architectures are carefully crafted at every scale, from millimeters to nanometers.
Adaptive, these composite materials and living structures often fulfill several functions at the same time: lightness, thermal or acoustic resistance, elasticity, waterproofing or even thermo-regulation. In certain species, we even observe remarkable faculties of resilience and self-repair.
Plant fiber:
between flexibility, rigidity and lightness
Remember the famous fable “The Oak and the Reed” by La Fontaine. The plant fiber of plants, a true composite formed of rigid crystalline zones and soft amorphous zones, is a naturally light and incredibly flexible structure. It absorbs shocks without breaking.
In the design of a vehicle or an airplane, for example, engineers have for years favored steel or aluminum. Biomimicry could make it possible to explore effective alternatives.
In Slovakia, an inventor has created a composite bicycle frame formed from a bidirectional fabric of bamboo fibers.
In addition to being light, flexible and resistant, bamboo grows quickly and stores carbon, which makes it a renewable material of quality. After numerous tests, the verdict is clear: the bamboo frame absorbs shocks better than a classic steel frame and does so without breaking.
The bamboo structure could very well revolutionise the structures of many components in different industries, starting with those of mobility.
Bird anatomy:
the necessary search for lightness
One of the greatest prowess imagined by nature, the one that has fiilled entire generations of inventor's dreams, is the flight of birds.
To be able to fly, sometimes over long distances, birds must have particularly light anatomies to minimise effort and energy expenditure. Their bone structure is therefore of obvious interest to analyse.
Let's travel to the Amazon rainforest: the toucan is a remarkable and colourful bird. Its beak is especially impressesive compared to its size. It measures almost a third of the animal.
Despite this imposing volume, it only represents one twentieth of the total mass of the toucan: practical for flying. It must, at the same time, be resistant to allow the bird to defend itself and hunt.
The compromise between lightness and strength is achieved thanks to a sandwich structure. The internal structure is spongy, light and composed of closed cell foam. It helps cushion and dissipate shocks.
This internal part is surrounded by strong and dense external membranes, made up of hexagonal plates of keratin, overlapping and glued together by organic glue. Enough to improve the robustness of the entire beak.
Even more surprising, this beak also fulfills a central functionality for the toucan's body: it allows it to regulate its body temperature above 16°C through a particularly effective heat dissipation mechanism.
Particularly optimised to absorb high energy shocks, this bio-composite nozzle can therefore inspire new mechanical structures to improve numerous products or components, from vehicles to airplanes, including sporting goods, and construction elements in construction, for example.
Note that birds are not the only ones with an anatomy designed to optimise the weight/resistance ratio. This is also the case for many land and sea animals, such as the cuttlefish!
Natural materials:
teachings of insects
and shellfish
On a finer scale, natural materials, such as those of insects, crustaceans and shellfish, have already enabled researchers to create new materials that are both light and resistant. Here are some particularly surprising examples.
Arthropods form a group of animals characterised by their segmented bodies. They include insects and crustaceans with a shell, an exoskeleton, called a cuticle.
It is very resistant and represents a line of defense for the animal. It absorbs shocks that may occur to protect the internal body.
It owes its robustness to an alternation of flexible and rigid layers. A team from the Wyss Institute at Harvard University in the United States has succeeded in reproducing these micro-structural and multi-layer properties to develop a material as hard and tenacious as aluminum, but twice as light.
This bio-plastic was named “Shrilk”. Composed of chitin, a flexible and resistant natural material, and fibroin silk proteins created by many insects, Shrilk is a natural, biocompatible and biodegradable compound.
Crédits images : ©Wyss Institute at Harvard University
In the automobile industry, for example, aluminum is gradually replacing steel because it is lighter. In more than fifty years, its quantity has increased from 38kg to more than 180kg on average per car. A trend which will continue in future to reach 250kg by 2028.
Thanks to its mechanical properties comparable to those of aluminum, its superior lightness and its recyclability, Shrilk is agreat alternative which could, in the long term, replace it! It could be used on a large scale in many industries. Renewable and mass-producible, it is perfectly compatible with additive manufacturing.
Mother-of-pearl:
toughness and thermal resistance
In many industries, components are subjected to high temperatures. A significant technical challenge.
Because at high temperatures, the mechanical properties of metals deteriorate, making them unusable.
The materials most used today to overcome this problem are ceramics, known for their strong resistance to hightemperatures. They are unfortunately very fragile, particularly in the face of the propagation of cracks.
The world of biomimicry has in-depth knowledge: it is a problem often encountered in living things which offers us a powerful source of inspiration.
Abalones are marine molluscs with shells. Its natural mother-of-pearl has a truly outstanding multi-layer microstructure.
Several French laboratories came together to study it. Thanks to this biological model, they managed to create a real artificial mother-of-pearl ten times more tenacious than conventional ceramics. This new ceramic can make it possible to reduce the size and therefore the mass of different ceramic parts.
Crédits images : ©Sylvain Deville, Florian Bouville, LSFC
Algorithms inspired by bone growth: optimise the design
structures
Biomimicry can go even further. Because in addition to being useful as a model for the creation of new materials, nature can inspire design algorithms.
Researchers and engineers sought to create new, more resistant, resource-efficient and lightweight structures, as well as innovative design methods inspired by life. Here is a relevant example.
A new 3D design algorithm was created by the companies Autodesk and APWorks to design internal partitions for the Airbus A320. These partitions, which separate the different parts of the cabin and support the crew members' seats, are 65% lighter than existing structures.
This software borrows from the principles of bone growth in which the regions most subject to mechanical stress are the most full and dense. The design algorithm tests a multitude of distinct structural configurations to select the least resource-intensive, while still meeting established constraints. The structure is thus optimised on the macro scale and on the micro scale.
Such an algorithm makes it possible to minimise the mass and materials of a structure while maintaining strength and robustness. Applied to structural design, its potential is immense, in various industries.
Crédits images : ©The Living
Other promising prospects for biomimicry in industrial sectors
