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Abstract Multi-welled energy landscapes arising in shells with nonzero Gaussian curvature typically fade away as their thickness becomes larger because of the increased bending energy required for inversion. Motivated by this limitation, we propose a strategy to realize doubly curved shells that are bistable for any thickness. We then study the nonlinear dynamic response of one-dimensional (1D) arrays of our universally bistable shells when coupled by compressible fluid cavities. We find that the system supports the propagation of bidirectional transition waves whose characteristics can be tuned by varying both geometric parameters as well as the amount of energy supplied to initiate the waves. However, since our bistable shells have equal energy minima, the distance traveled by such waves is limited by dissipation. To overcome this limitation, we identify a strategy to realize thick bistable shells with tunable energy landscape and show that their strategic placement within the 1D array can extend the propagation distance of the supported bidirectional transition waves. 

Fluidic soft actuators are enlarging the robotics toolbox by providing flexible elements that can display highly complex deformations. Although these actuators are adaptable and inherently safe, their actuation speed is typically slow because the influx of fluid is limited by viscous forces. To overcome this limitation and realize soft actuators capable of rapid movements, we focused on spherical caps that exhibit isochoric snapping when pressurized under volume-controlled conditions. First, we noted that this snap-through instability leads to both a sudden release of energy and a fast cap displacement. Inspired by these findings, we investigated the response of actuators that comprise such spherical caps as building blocks and observed the same isochoric snapping mechanism upon inflation. Last, we demonstrated that this instability can be exploited to make these actuators jump even when inflated at a slow rate. Our study provides the foundation for the design of an emerging class of fluidic soft devices that can convert a slow input signal into a fast output deformation. 

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.