Durable Foam Structure Inspired by Pomelos

Innovation: Academia

Texas A&M University

2018

Image: Fahd Khan / Unsplash / CC BY SA - Creative Commons Attribution + ShareAlike

Manage Impact

An impact is a high force or mechanical shock that happens over a short period of time, such as a hammer hitting a nail rather than a hand pushing slowly against a wall. Because of their speed and force, impacts don’t allow materials to slowly adjust to the force, which can lead to cracks, ruptures, and complete breakage. Therefore, living systems have strategies that can absorb, dissipate, or otherwise survive that force without the need to add large amounts of material. For example, the Toco toucan’s large beak is very lightweight, yet can withstand impacts because it’s made of a composite material with rigid foam inside and layers of a hard, fibrous material outside.

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Manage Compression

When a living system is under compression, there is a force pushing on it, like a chair with a person sitting on it. When evenly applied to all sides of a living system, compression results in decreased volume. When applied on two sides, it results in deformation, such as when pushing on two sides of a balloon. This deformation can be temporary or permanent. Because living systems must retain their most efficient form, they must ensure that any deformation is temporary. Managing compression also provides an opportunity to lessen the effects of other forces. Living systems have strategies to help prevent compression or recover from it, while maintaining function. For example, African elephant adults weigh from 4,700 to 6,048 kilograms. Because they must hold all of that weight on their four feet, the tissues of their feet have features that enable compression to absorb and distribute forces.

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Foam structure from Texas A&M University has a non-uniform porosity that improves its impact resistance.

Benefits

Reduced costs
Lightweight

Applications

Armor and protection
Packaging

UN Sustainable Development Goals Addressed

Goal 12: Responsible Production & Consumption

The Challenge

Foam is often used in helmets and other protective equipment to absorb impact, shock, and vibration. However, after an incident of impact, most helmets must be replaced, as the foam material is damaged. If foam equipment was more durable, products would be able to withstand impact without replacement, decreasing foam waste.

Innovation Details

The durable foam structure has a nonuniform pore distribution with an open-cell skeleton, which is generated through the Voronoi tessellation (a proximity diagram that divides a plane into regions). Essentially, the foam contains pores of varying sizes, giving it superior energy dissipation properties. When impacted, these pores collapse, absorbing shock and protecting the material from extensive damage.

Biomimicry Story

Fruits like grapefruit and pomelo have excellent damping properties due to the hierarchical organization of their peels. When pomelo fruits fall from the ground, air pockets within the peel collapse like a cushion, absorbing the energy of impact and protecting the peel from damage.

See Related Content

close up photo of seven pomelo citrus fruits, one with exposed orange flesh

Biological Strategy

Hierarchical Organization of Peel Confers Impact Resistance

Pomelo

The pomelo fruit has excellent damping properties due to the hierarchical organization of its composite peel

yellow fruit hanging from tree with green leaves

Biological Strategy

Pressurized Struts Dissipate Impact

Pomelo

Skin of pomelos absorb impact by rupturing fluid-filled struts

References

Journal article

A Model for the Design of a Pomelo Peel Bioinspired Foam

ASME: Journal of Mechanical Design

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