Spiky-joint: a bioinspired solution to combine mobility and support

Khaheshi, Ali; Gorb, Stanislav N.; Rajabi, Hamed

doi:10.1007/s00339-021-04310-5

Cited by 6 publications

(7 citation statements)

References 30 publications

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“…This reversible nonlinear behaviour of the double-spiral comes from its geometry and can be tuned by changing its design variables. The variable stiffness structures, such as our double-spiral, are of particular interest in shape morphing applications, where low stiffness is necessary during shape change and high stiffness is needed for load bearing purposes when the shape change is completed [35][36][37][38].…”

Section: Discussionmentioning

confidence: 99%

Double-spiral: a bioinspired pre-programmable compliant joint with multiple degrees of freedom

Jafarpour

Gorb

Rajabi

2023

J. R. Soc. Interface.

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Geometry and material are two key factors that determine the functionality of mechanical elements under a specific boundary condition. Optimum combinations of these factors fulfil desired mechanical behaviour. By exploring biological systems, we find widespread spiral-shaped mechanical elements with various combinations of geometries and material properties functioning under different boundary conditions and load cases. Although these spirals work towards a wide range of goals, some of them are used as nature's solution to compactify highly extensible prolonged structures. Characterizing the principles underlying the functionality of these structures, here we profited from the coiling–uncoiling behaviour and easy adjustability of logarithmic spirals to design a pre-programmable compliant joint. Using the finite-element method, we developed a simple model of the joint and investigated the influence of design variables on its geometry and mechanical behaviour. Our results show that the design variables give us a great possibility to tune the response of the joint and reach a high level of passive control on its behaviour. Using 3D printing and mechanical testing, we replicated the numerical simulations and illustrated the application of the joint in practice. The simplicity, pre-programmability and predictable response of our double-spiral design suggest that it provides an efficient solution for a wide range of engineering applications, such as articulated robotic systems and modular metamaterials.

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Section: Discussionmentioning

confidence: 99%

Double-spiral: a bioinspired pre-programmable compliant joint with multiple degrees of freedom

Jafarpour

Gorb

Rajabi

2023

J. R. Soc. Interface.

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“…We could tune all these features by changing the design variables of the double-spirals and controlling the structural stiffness in each direction. These characteristics can be a great advantage to many engineering structures, such as mechanical hinges [46,47] biomedical implants, [19] asymmetric casts and splints, [48] flexible body armors, [49] and loadbearing yet collision-resistant kites. [50] Programmed shape change in response to mechanical loads is another interesting property of the metastructures.…”

Section: Discussionmentioning

confidence: 99%

Double‐Spirals Offer the Development of Preprogrammable Modular Metastructures

2023

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Metamaterials with adjustable, sometimes unusual properties offer advantages over conventional materials with predefined mechanical properties in many technological applications. A group of metamaterials, called modular metamaterials or metastructures, are developed through the arrangement of multiple, mostly similar building blocks. These modular structures can be assembled using prefabricated modules and reconfigured to promote efficiency and functionality. Herein, a novel modular metastructure is developed by taking advantage of the high compliance of preprogrammable double‐spirals. First, the mechanical behavior of a four‐module metastructure under tension, compression, rotation, and sliding is simulated using the finite‐element method. Then, 3D printing and mechanical testing are used to illustrate the tunable anisotropic and asymmetric behavior of the spiral‐based metastructures in practice. The results show the simple reconfiguration of the presented metastructure toward the desired functions. The mechanical behavior of single double‐spirals and the characteristics that can be achieved through their combinations make our modular metastructure suitable for various applications in robotics, aerospace, and medical engineering.

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“…Recent studies have tested and verified the scalability of some of the wing-derived strategies. A few examples include the development of durable kites, stiffness-varying splints, insect-inspired wings for medium-sized flapping-wing drones, airplane wing models and origami arms that resist collisions by undergoing reversible buckling, extensible robotic arms, confined-space crawling robots, and unlockable revolute joints ( 27 , 39 – 46 ). Based on our results, the double-layer membrane can work at different scales, but its effectiveness will clearly depend on overall size, relative wall thickness and section shape, and the properties of the material.…”

Section: Discussionmentioning

confidence: 99%

An insect-inspired asymmetric hinge in a double-layer membrane

Rajabi

Eraghi

Khaheshi

et al. 2022

Proc. Natl. Acad. Sci. U.S.A.

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Insect wings are deformable airfoils, in which deformations are mostly achieved by complicated interactions between their structural components. Due to the complexity of the wing design and technical challenges associated with testing the delicate wings, we know little about the properties of their components and how they determine wing response to flight forces. Here, we report an unusual structure from the hind-wing membrane of the beetle Pachnoda marginata . The structure, a transverse section of the claval flexion line, consists of two distinguishable layers: a bell-shaped upper layer and a straight lower layer. Our computational simulations showed that this is an effective one-way hinge, which is stiff in tension and upward bending but flexible in compression and downward bending. By systematically varying its design parameters in a computational model, we showed that the properties of the double-layer membrane hinge can be tuned over a wide range. This enabled us to develop a broad design space, which we later used for model selection. We used selected models in three distinct applications, which proved that the double-layer hinge represents a simple yet effective design strategy for controlling the mechanical response of structures using a single material and with no extra mass. The insect-inspired, one-way hinge is particularly useful for developing structures with asymmetric behavior, exhibiting different responses to the same load in two opposite directions. This multidisciplinary study not only advances our understanding of the biomechanics of complicated insect wings but also informs the design of easily tunable engineering hinges.

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Spiky-joint: a bioinspired solution to combine mobility and support

Cited by 6 publications

References 30 publications

Double-spiral: a bioinspired pre-programmable compliant joint with multiple degrees of freedom

Double-spiral: a bioinspired pre-programmable compliant joint with multiple degrees of freedom

Double‐Spirals Offer the Development of Preprogrammable Modular Metastructures

An insect-inspired asymmetric hinge in a double-layer membrane

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