High-Performance Biocomposites Inspired by Trees

Innovation: Industry

Strong by Form

Modify Size/Shape/Mass/Volume

Many living systems alter their physical properties, such as size, shape, mass, or volume. These modifications occur in response to the living system’s needs and/or changing environmental conditions. For example, they may do this to move more efficiently, escape predators, recover from damage, or for many other reasons. These modifications require appropriate response rates and levels. Modifying any of these properties requires materials to enable such changes, cues to make the changes, and mechanisms to control them. An example is the porcupine fish, which protects itself from predators by taking sips of water or air to inflate its body and to erect spines embedded in its skin.

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Modify Material Characteristics

The materials found in living systems are variable, yet often made from the same basic building blocks. For example, all insect exoskeletons consist of a material called chitin. Because material resources are limited, each material within or used by a given living system must frequently serve multiple purposes. Therefore, living systems have strategies to modify materials’ softness, flexibility, and other characteristics. To ensure survival, the benefits of these modifications must outweigh the living system’s energy and material expenditure to generate them. For example, spiders store the liquid components of spider silk in a gland, converting them into silk thread when needed. Some threads have different characteristics, such as elasticity and UV reflectance, than others.

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Physically Assemble Structure

Living systems use physical materials to create structures to serve as protection, insulation, and other purposes. These structures can be internal (within or attached to the system itself), such as cell membranes, shells, and fur. They can also be external (detached), such as nests, burrows, cocoons, or webs. Because physical materials are limited and the energy required to gather and create new structures is costly, living systems must use both conservatively. Therefore, they optimize the structures’ size, weight, and density. For example, weaver birds use two types of vegetation to create their nests: strong, a few stiff fibers and numerous thin fibers. Combined, they make a strong, yet flexible, nest. An example of an internal structure is a bird’s bone. The bone is comprised of a mineral matrix assembled to create strong cross-supports and a tubular outer surface filled with air to minimize weight.

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Prevent Fatigue

When materials that comprise living systems are subjected to repeated loads, they can weaken over time. This is called fatigue and it can lead to cracks and eventually failure. However, fatigue doesn’t occur just anywhere on a material; the cracks usually start in areas subjected to elevated local stresses. Therefore, living systems often employ shapes, materials, and/or smooth transitions to decrease the potential for fatigue. An example of using shape is found in brown algae, an intertidal seaweed. Rather than being bent by the constant flow forces of waves and currents, its shape causes it to be pulled. This reduces stress by roughly 800 times compared to another species that bends with the flow, ultimately reducing structural fatigue.

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Prevent Deformation

When a living system undergoes compression, tension, shear, bending, or twisting, its internal inter-molecular forces can often resist these forces and even change shape temporarily, returning to the original shape when the forces stop. However, if the force is too strong or lasts too long, permanent deformation or structural failure can occur, resulting in death. Therefore, living systems have strategies to resist deformation or help ensure limited deformation. For example, bones have thin crystals and proteinaceous fibers that provide strength and flexibility, protecting them from forces that would otherwise cause deformation on a daily basis.

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Strong by Form mimics the growth patterns of trees to fuse the sustainability of wood with the performance of advanced composites.

Benefits

High-performance structures
Near-zero waste
Use of carbon-sequestering material
Fully automated from design to manufacturing

Applications

Architecture
Automotive
Infrastructure
Maritime vehicles
Furniture

UN Sustainable Development Goals Addressed

Goal 9: Industry Innovation & Infrastructure
Goal 11: Sustainable Cities & Communities
Goal 12: Responsible Production & Consumption

The Challenge

Recognizing the strength and flexibility of wood, humans––like birds and beavers before us––have long used it for construction.

But when using wood, we have tended to focus on supporting our structures at the macro scale, using large, straight beams and planks that concentrate intense pressure at specific points and follow relatively limited design options. To use more fluid shapes and designs, and to avoid weak joints, we’ve developed energy-and-resource-intensive materials like reinforced concrete, fiberglass, and plastics.

There hasn’t been a good way to get the sustainability of wood and the functionality of composite materials at the same time.

Innovation Details

Architects and inventors at Strong by Form have devised a manufacturing process that mimics the way trees themselves shape their materials for structural performance, opening up revolutionary possibilities for the forms wood construction can take.

It starts by cutting wood into small flakes. Then, design software arranges the direction and distribution of flakes to bear the loads that the material needs to support. Advanced robotics then lay down the flakes with a bit of binding resin, matching the prescribed three-dimensional pattern, using minimal material to get optimal performance.

Since Strong by Form’s manufacturing process uses wood flakes, not sawn timber, it can make use of a wide diversity of tree species, and a greater proportion of each tree, including smaller branches and parts with irregular forms.

Strong by Form’s engineered lightweight wood product reduces the amount of material needed to build structures and the costs to transport them, yet the material is strong enough to become an alternative to highly polluting materials such as steel, aluminum, concrete, or fiber-reinforced plastics, in buildings, vehicles, and furniture.

Biological Model

To withstand forces that would break them, trees have evolved a strategic way of growing: they form their wood to compensate for those forces. As a trunk or branch grows, it will adjust the size and number of different kinds of cells, the thickness of cell walls, and the compounds within them.

In hardwood trees, that results in rings being thicker on the top side of branches, stuffed with lots of stretchy fibers to accommodate the downward pull of tension. Softwood trees build up the lower side of branches with rigid lignin to resist the crushing stress of compression. In all trees, structural support is highly adaptable, working at odd angles and curves, and built right into the material used for construction, at the micro scale.

See Related Strategy

Biological Strategy

Structure Distributes Stress

Scots pine

Trunks and branches of trees withstand external stresses through load-adaptive growth.

Ray of Hope Prize®

The Ray of Hope Prize celebrates nature-inspired solutions addressing the world’s biggest environmental and sustainability challenges. Created in honor of Ray C. Anderson, founder of Interface, Inc. and a business and sustainability leader, the $100,000 Ray of Hope Prize helps startups cross a critical threshold in becoming viable businesses by amplifying their stories and providing them with equity-free funding. The prize shines a light on the innovative, nature-inspired solutions that we need to build a sustainable and resilient world. Strong by Form was selected as a finalist for the 2022 Ray of Hope Prize.

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Sun rays filter through the forest canopy and shine upon a rocky creek

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