Applying Bio-Inspired hierarchical design to jamming technology: Improving density-efficient mechanical properties and opening application spaces

In the soft-robotics field, bio-inspiration is often cited, pointing to the animal-like forms created—however, the concept of hierarchical architecture common to biological materials has yet to be applied effectively. Here, it is shown how that by considering the hierarchical structure of the medium (primary level), the organization of jamming media (secondary level), and the organization of jammers (tertiary level) new functionalities not possible with conventional jamming technology can be obtained. This is accomplished at the three layers enumerated above. At the primary level, optimal compositions of fibrous flakes and grains are identified to improve stiffness and strength per unit weight; fish-inspired ganoid scales are used to create flexible armors. At the secondary level, layers and grains are combined in the tensile and compressive faces of beams to maximize mechanical properties, while ganoid scales of different compositions are layered to create mechanical gradients, among other combinations of jamming media. Finally, at the tertiary level, the isotropy of triadically woven jammers is demonstrated relative to traditional biaxial jammers; a cylindrical “finger-trap” weave with adjustable radius is shown. The improved mechanical weight-efficiency, anisotropy control, mechanical property gradients, and other features enabled by considering hierarchical design in jamming promise new application spaces for an established field.