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The term ‘flexural tensegrity’ applies to beam-like structures composed of segments in unilateral contact, whose integrity under flexion is provided by tendons (cables), tensioned and later anchored at the end segments. In addition to the cable tension, the constitutive response depends upon the shape of the contact surfaces between consecutive segments, identified by the corresponding pitch lines and constructed with a double couple of conjugate profiles, in order to achieve an internal constraint equivalent to a spring hinge. The response is non-local in type, because the cable elongation, and consequently the stiffness of the spring hinges, depends upon the rotations of all the segments, but this effect becomes negligible under moderate deflections. In this case, the structure can be approximated with an elastica in the continuum limit. Testing of prototypes, manufactured with a 3D printer, shows a very good agreement with the theoretical predictions for different designs of the spring hinges. The system, whose stiffness can be functionally graded and actively controlled, can be packaged when the cable is slack and deployed by pulling the cable at one extremity. It appears particularly suitable to build soft arms for robotics or deployable compliant booms for aerospace applications.

An optimal design approach is developed for a self-driven, self-locking tape-spring under a pure bending load in deployable space structures. A novel hinge with three tape springs is investigated and designed via an optimization process. Firstly, we investigate the steady-state moment and maximum stress of the hinge during deploying and folding processes using physics-based simulations. Experimental analyses are then conducted to verify the physics-based simulation results. Secondly, a parametric analysis is carried out to prove that both the tape spring thickness and subtended angle have significant effect on steady-state moment. A Response Surface Methodology (RSM) is employed to define an optimal surrogate model aimed at maximizing the steady-state moment, subjected to allowable stress. Finally, the Large Scale Generalized Reduced Gradient (LSGRG) optimization algorithm is used to solve the optimal design problem. Optimization results show that steady-state moment is increased by 19.5% while satisfying a maximum stress constraint. The proposed method is promising for designing novel deployable structures with high stability and reliability.

Triangulated cylindrical origami (TCO) has multiple parameters that can control and predict the transformation process. In the present study, the Kresling pattern was constructed by congruent triangles in helical formation. It is shown that triangle angles have a huge impact on load-bearing ability. Experimental tests and mathematical calculation of Kresling-patterned triangulated cylinder in different α angles with one constant angle for all specimens were developed. This study aims to understand the relevancy and distinction of experimental and mathematical approaches with axial load in the process of creating single unit Kresling pattern origami. The specimens were tested with the axial test without applying twist movement on it. The structures could hold up to 176 N for the most significant angle observed. The reversible deformation of TCO from deployed to folded state with axial load was performable with α angle below 50° with 136 N of load. Based on the experiment, the larger the α angle, the more dependent on the twist. The axial load test without twist movement shows similar energy distribution during deformation process. Further observations related to overall strength of TCO due to difference in the value of mathematical and experimental results are required. The present research could give a contribution related to the design method for the fabrication of Kresling pattern origami.

Deployable kinematic structures can transform themselves from a small closed configuration to a large deployed one. These structures are widely used in many engineering fields including aerospace, architecture, robotics and to some extent within HCI. In this paper, we investigate the use of a symmetric spherical deployable structure and its application to interface control. We present HoberUI, a bimanual symmetric tangible interface with 7 degrees of freedom and explore its use for manipulating 3D environments. We base this on the toy version of the deployable structure called the Hoberman sphere, which consists of pantographic scissor mechanisms and is capable of homogeneous shrinkage and expansion. We first explore the space for designing and implementing interactions through such kinematic structures and apply this to 3D object manipulation. We then explore HoberUI’s usability through a user evaluation that shows the intuitiveness and potential of using instrumented kinematic structures as input devices for bespoke applications.

Variable-diameter deployable carbon fiber reinforced polymer (CFRP) composites possess deformation and load-bearing functions and are composed of stiff-flexible coupled preforms and matrix. The stiff-flexible coupled preform, serving as the reinforcing structure, directly determines the deployable properties, and its forming technology is currently a research challenge. This paper designs a braiding and needle-punching (BNP) composite preform forming technology suitable for stiff-flexible coupled preforms. Before forming, the preform is partitioned into flexible and rigid zones, with braiding and needle-punching performed layer by layer in the respective zones. A retractable rotating device is developed to form the stiff-flexible coupled preform, achieving a diameter variation rate of up to 26.6% for the BNP preform. A structural parameter model is also established to describe the geometric parameter changes in the deformation and load-bearing areas of the preform during deployment as a function of the braiding angle. Based on experiments, this paper explains the performance changes of BNP composites concerning the structural parameters of the preform. Experimental analysis shows that as the braiding angle increases, the tensile performance of BNP composites significantly decreases, with the change rate of tensile strength first decreasing and then increasing. Additionally, when the braiding angle is less than 21.89°, the impact toughness of BNP composites remains within the range of 83.66 ± 2 kJ/m 2 . However, when the braiding angle exceeds 21.89°, the impact toughness of BNP composites gradually decreases with increasing braiding angle. Furthermore, a hybrid agent model based on Latin hypercube sampling and error back-propagation neural network is developed to predict the tensile and impact properties of BNP composites with different structural parameters, with maximum test relative errors of 1.89% for tensile strength and 2.37% for impact toughness.

The deployable composite cylindrical thin-walled (DCCTW) hinges have application prospects as deployable structures of satellite and solar array, but the mechanical characteristics of the DCCTW hinges have not been considered comprehensively. Taking progressive damage into consideration, the mechanical properties of DCCTW hinges have been reassessed, and a new optimal design method is presented in this paper. Firstly, a simplified model of DCCTW hinge was established. Both analytical and numerical analyses of the simplified model have been conducted. Secondly, the finite element (FE) method has been used to analyze the folding and torsional behavior of DCCTW hinge based on progressive damage theory. Thirdly, design of experiment (DOE) has been carried out using optimal Latin hypercube sampling method. The surrogate model has been established based on the DOE process and elliptical basis functions (EBF). Sensitivity analysis of mass, peak moment of folding, torsional failure angle, and peak moment of torsion have been conducted. Lastly, considering lightweight, the higher peak moment of folding and torsion, the optimization was implemented by multi-objective particle swarm optimization (MOPSO) algorithm, two different optimal designs of DCCTW hinge have been obtained at the same time. The maximum relative error between FE analysis results and optimal design results with the surrogate model is 7.46%, which also reflects the accuracy of the surrogate model. The proposed optimization method can be applied to optimize other composite flexible hinges in consideration of progressive damage.

The paper discusses seismic performance of deployable brace member as well as its application in single-story single-bay frame by using finite element method in OpenSees Navigator. Even though deployable structure has wide applications in engineering area, it is almost blank for earthquake (seismic) engineering. A finite element deployable brace model consisting two identical struts and a revolute joint is built in this paper. The model considers joint clearance and initial eccentricity to accord practical situation. Hysteresis analysis has been done on the brace model as well as its application. The results show deployable structure provides sufficient lateral stiffness and ductility. Strut eccentricity is the key factor affecting the capacity of the strut and buckling strength, while joint clearance also has influence on the strut capacity and energy dissipation.

Globally, large-scale natural disasters are occurring more frequently due to climatic and environmental changes. In addition, the disaster risk for infrastructures, mainly bridges, has become a vulnerability issue because reinforced concrete bridge structures are being directly exposed to the natural environment. Bridge structures linking cities or prefectures are destroyed in the aftermath of natural disasters and must be rebuilt. As a post-disaster measure, rapid reconstruction of damaged bridges and the reconnection of transportation systems between impacted locations and urban areas are the main problems encountered. This study aims to solve these problems through the application of a novel concept of an emergency bridge based on origami-inspired post-buckling theory, in conjunction with previous studies investigating the optimal deployable structure of scissors-type bridges. This study applied a novel design method for scissor-type bridges that use influence line diagrams and equilibrium equations. The proposed methods can determine the size of each member appropriately while providing the minimum and maximum values of the influence line border when carrying light vehicles by analyzing variations in the live load distribution on the structure. In the case of heavy vehicles passing over a bridge, the fundamental internal axial forces and bending moments were obtained, which provided design parameters for improving the load-carrying capacity of the structure. The proposed emergency bridge has a lower theoretical stress than that of a double-Warren truss.

The use of deployable structures has a wide range of applications nowadays. They can be transformed from a closed compact configuration to a predetermined expanded form, in which they are stable and can carry loads. This article describes a sort of deployable structure that has been patented by researchers of two Spanish institutions: San Pablo CEU University and Eduardo Torroja Institute. Geometric aspects are key to accomplish an efficient folding and unfolding procedure along with an optimum structural behavior when the structure is deployed. Tensioned cables are essential in these structures. The main goal is to make the cable acquire its maximum length when the structure is fully deployed. This will avoid complex operations of post-tensioning in order to make the cable perform its function.

From stadium covers to solar sails, we rely on deployability for the design of large-scale structures that can quickly compress to a fraction of their size 1 – 4 . Historically, two main strategies have been used to design deployable systems. The first and most frequently used approach involves mechanisms comprising interconnected bar elements, which can synchronously expand and retract 5 – 7 , occasionally locking in place through bistable elements 8 , 9 . The second strategy makes use of inflatable membranes that morph into target shapes by means of a single pressure input 10 – 12 . Neither strategy, however, can be readily used to provide an enclosed domain that is able to lock in place after deployment: the integration of a protective covering in linkage-based constructions is challenging and pneumatic systems require a constant applied pressure to keep their expanded shape 13 – 15 . Here we draw inspiration from origami—the Japanese art of paper folding—to design rigid-walled deployable structures that are multistable and inflatable. Guided by geometric analyses and experiments, we create a library of bistable origami shapes that can be deployed through a single fluidic pressure input. We then combine these units to build functional structures at the metre scale, such as arches and emergency shelters, providing a direct route for building large-scale inflatable systems that lock in place after deployment and offer a robust enclosure through their stiff faces. Origami-inspired multistable structures that can be inflated from flat to three dimensions have been designed; a library of foldable shapes is created and then combined to build metre-scale functional structures.