Materials capable of dramatically changing their stiffness along specific directions in response to an external stimulus can enable the design of novel robots that can quickly switch between soft/highly–deformable and rigid/load–bearing states. While the jamming transition in discrete media has recently been demonstrated to be a powerful mechanism to achieve such variable stiffness, the lack of numerical tools capable of predicting the mechanical response of jammed media subjected to arbitrary loading conditions has limited the advancement of jamming-based robots. To overcome this limitation, we introduce a 3D finite–element-based numerical tool that predicts the mechanical response of pressurized, infinitely–extending discrete media subjected to arbitrary loading conditions. We demonstrate the capabilities of our numerical tool by investigating the response of periodic laminar and fibrous media subjected to various types of loadings. We expect this work to foster further numerical studies on jamming–based soft robots and structures by facilitating their design, as well as providing a foundation for combining various types of jamming media to create a new generation of tunable composites.
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A Modeling Framework for Jamming Structures
Jamming is a structural phenomenon that provides tunable mechanical behavior. A jamming structure typically consists of a collection of elements with low effective stiffness and damping. When a pressure gradient, such as vacuum, is applied, kinematic and frictional coupling increase, resulting in dramatically altered mechanical properties. Engineers have used jamming to build devices from tunable‐stiffness grippers to tunable‐damping landing gear. This study presents a rigorous framework that systematically guides the design of jamming structures for target applications. The force‐deflection behavior of major types of jamming structures (i.e., grain, fiber, and layer) in fundamental loading conditions (e.g., tension, shear, and bending) is compared. High‐performing pairs (e.g., grains in compression, layers in shear, and bending) are identified. Parameters that go into designing, fabricating, and actuating a jamming structure (e.g., scale, material, geometry, and actuator) are described, along with their effects on functional metrics. Two key methods to expand on the design space of jamming structures are introduced: using structural design to achieve effective tunable‐impedance behavior in specific loading directions, and creating hybrid jamming structures to utilize the advantages of different types of jamming. Collectively, this study elaborates and extends the jamming design space, providing a conceptual modeling framework for jamming‐based structures.
more » « less- NSF-PAR ID:
- 10451991
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Functional Materials
- Volume:
- 31
- Issue:
- 16
- ISSN:
- 1616-301X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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