Effect of discreteness on domain wall stability in a plate coupled to a foundation of bistable elements

Journal of the Mechanics and Physics of Solids · 2026-04-17

Airfoil Decambering for Gust Load Alleviation Using a Bi-stable Hinge

2026-01-08

Wing sections with bistable hinges outfitted on trailing edge flaps provide a promising means for passively rejecting gust loads on an aircraft. This study found that there exists a two-way coupling between the aerodynamic loads experienced by the airfoil and the deflection of the bistable hinge and corresponding flap. The current work demonstrates how the energy wells of a bistable hinge system can be configured to introduce decambering of the airfoil when stall limits are approached. By expressing the interdependent coupling between the global flow state and the hinge material properties, a bistable hinge can be designed to produce snap-through transitions when prescribed aerodynamic states are reached. The efficacy of this bistable hinge integration strategy is shown in an experimental campaign, where passive alleviation of aerodynamic loads are produced in the vicinity of airfoil stall limits.

Phonon controlled mechanical memory via pinning and depinning of transition waves

arXiv (Cornell University) · 2026-03-02

Multistable mechanical metamaterials enable programmable transitions between discrete stable states through propagating kink transition waves (TWs). Yet controlling these kinks typically requires local actuation or high-energy deformation, limiting scalability. Here we demonstrate a universal strategy for pinning and depinning TWs using local defects and boundary phonon excitations. Inspired by phonon-dislocation interactions in crystalline solids, we use pairs of phonons that form a beating envelope resonant with the pinned kink's translational mode, which lies within a phononic band gap. This resonant coupling efficiently transfers energy to the kink, allowing it to overcome defect barriers and propagate across impurities. The proposed mechanism enables application of these systems as information processing units in mechanical computing, namely as scalable and more robust mechanical memory.

An integrated modular platform of pneumatic actuators for adaptive and reusable soft robots

Journal of Intelligent Material Systems and Structures · 2026-05-22

This study presents a modular pneumatic actuator system for soft robotics, designed to improve reconfigurability, adaptability, and deployment efficiency. The system consists of a standardized and extensible set of functional modules, including elongation, bending, twisting, and stimuli-responsive modules, each systematically characterized by its pressure–deformation behavior. These modules can be (re)assembled according to task-specific requirements, enabling the rapid construction of soft robotic platforms with customized actuation strategies. We demonstrate the versatility of this approach through three representative systems: a bioinspired trunk-like robot, a soft crawling robot, and a reconfigurable three-fingered gripper. Each example highlights key advantages of modularity, such as structural adaptability, environmental responsiveness, and object-specific grasping. The results show that this strategy supports scalable, low-cost, and reusable actuator designs.

Phonon controlled mechanical memory via pinning and depinning of transition waves

ArXiv.org · 2026-03-02

Multistable mechanical metamaterials enable programmable transitions between discrete stable states through propagating kink transition waves (TWs). Yet controlling these kinks typically requires local actuation or high-energy deformation, limiting scalability. Here we demonstrate a universal strategy for pinning and depinning TWs using local defects and boundary phonon excitations. Inspired by phonon-dislocation interactions in crystalline solids, we use pairs of phonons that form a beating envelope resonant with the pinned kink's translational mode, which lies within a phononic band gap. This resonant coupling efficiently transfers energy to the kink, allowing it to overcome defect barriers and propagate across impurities. The proposed mechanism enables application of these systems as information processing units in mechanical computing, namely as scalable and more robust mechanical memory.

Transition waves in a beam coupled to a bistable foundation with a symmetric energy landscape

The Journal of the Acoustical Society of America · 2025-04-01

Multistable metamaterials, capable of adopting multiple stable configurations, offer versatile control over the shape and mechanical properties of systems. Transition waves (TWs), which propagate spatially through state transitions, provide a promising mechanism for reconfiguring such materials. While TWs in systems with asymmetric energy landscapes propagate stably by transitioning from higher to lower energy states, they require additional energy input to reset the structure. This work explores a multistable system with a reconfigurable surface shape, comprising an elastic slender beam coupled to a foundation of bistable elements, each with a symmetric energy landscape. The symmetric landscape enables TWs with tunable speeds, energy, and propagation distances, which can be controlled by boundary impact speed. The stop position of the TW forms a stable domain wall, separating regions of the beam in distinct stable states. Leveraging the relationship between impact speed and propagation distance, we propose a dynamic strategy for reversible surface shape reconfiguration using sequential impulses to generate targeted configurations. The feasibility of this strategy for shape control of multistable systems has been confirmed experimentally, using buckled double-beams as bistable elements.

Dynamics and design of passive tails for enhanced stability of motion

Bioinspiration & Biomimetics · 2025-05-22

In this work, we study the nonlinear dynamics of tail motion using numerical simulations and experiments. Our simulations are based on a discrete model comprising rigid cylinders (representing vertebrae) coupled by longitudinal, shear, and bending springs (representing tissues). We consider how various parameter combinations, such as geometric and stiffness gradients in the tail, affect the dynamic response of tails subjected to impulse loading. Using numerical and experimental approaches, we quantify pulse propagation in tails, demonstrating that flexible tails can support a stable wavefront. By incorporating a gradient that gradually decreases the length of each vertebra (geometric gradient) and the stiffness of its connecting tissues (stiffness gradient), we significantly enhance the lateral displacement and velocity of the propagating pulse towards the tip. We show that this effect can be used to improve stability of robotic vehicles subjected to impulses.

Computation of Material Property Fields in Heterogeneous and Multi-Material Systems Using Inverse Gauss-Seidel Method

SSRN Electronic Journal · 2025-01-01

Pneumatically controlled lattices with tunable mechanical behavior

Communications Engineering · 2025-12-13

Buckling is a common failure mode in lattice structures, limiting their use in some applications. The tendency of a strut to buckle is related to the local nodal connectivity. In this work, we introduce a pneumatic actuation strategy to actively tune the mechanical behavior of lattice structures by locally reconfiguring their effective nodal connectivity. By selectively inflating pneumatic actuators embedded in the lattice into spatial patterns with varying levels of connectivity, we demonstrate a method to modulate mechanical properties, including stiffness and buckling response. The most reinforced pattern can lead to 121.6% improvement in buckling strength relative to the regular lattice itself. Additionally, the post-buckling behavior of pneumatically controlled lattices can be programmably tuned by varying the input air pressure signals. The pneumatically controlled lattices reduced the peak acceleration by 50.9%, demonstrating enhanced impact mitigation capability. These results show that pneumatic actuation provides a versatile approach to enhancing structural performance under both static and dynamic loading. Since this strategy does not rely on multi-material interfaces or specific cell topologies, it can be broadly applied to optimize a wide range of lattice architectures. Lattice structures enable programmable mechanics but often require complex manufacturing or electronic systems. Xiaoheng Zhu, Yucong Hua and colleagues present a pneumatic control method that is easily reconfigurable and suitable for diverse structural applications

Design of nondeterministic architected structures via bioinspired distributed agents

Science Advances · 2025-05-14 · 1 citations

Nature manufactures structures via decentralized processes involving groups of agents. This is fundamentally different from traditional manufacturing, where objects are produced via sequences of predefined steps. In this work, we explore the idea of using simulated "swarms" of simple agents to generate new designs for architected materials in a decentralized, bioinspired manner. Individual agents choose their own actions based solely on information in their immediate environment, with no centralized control. The structures that these processes produce are the result of the collective action of the individual agents, rather than a predetermined design. We build an integrated platform for determining "rule-structure-property" relationships, analogous to process-structure-property relationships in materials science. The platform simulates agent behaviors to show how different rules and different environments result in different structures. We then three-dimensional print these and perform finite element analysis to experimentally and numerically characterize mechanical properties, including tensile strength and energy dissipation.