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Scissor structures, widely used in kinetic architecture, have been researched for over six decades. However, most studies focus on the deployability of the scissor structures, often disregarding the potential transformability of scissor loops that allow changing the curvature. Three scissor units, namely, translational, polar, and angulated units, do not adhere to the trajectory of an arc suitable for a transformable canopy structure. Although the deployment route of the polar version aligns with this trajectory, it is impractical for achieving transformability due to deviations. Therefore, the paper presents a novel approach to optimize generalized scissor linkages (GSLs), consisting of symmetrical and identical scissor units. Defined by three variables, GSL is introduced to address the transformability issue, and the optimization method is developed. According to this method, the selected polar scissor is modified to synthesize the GSL version. It is demonstrated that no GSL is composed of identical and symmetrical units deploying precisely along the arc trajectory. Nevertheless, the proposed optimization method enables the output GSL to converge toward the desired route. Three basic scissor unit types can be represented by a single parameterized GSL, effectively unifying different scissor linkages under a single definition. Practical Applications: Scissor linkages find extensive applications in kinetic architecture, such as domes, canopies, tents, emergency bridges, temporary shelters, and responsive facades. Existing studies on such linkages predominantly focus on deployed and contracted configurations of these mechanical structures. This study diverges by attempting to establish intermediate phases for designing such structures that can adapt to changing environmental conditions or user needs. To achieve the objective, the scissor linkage must move within a defined range, conceptualized as an arc of a circle. For instance, by tracking the movement of the sun, one can ensure a consistent positioning of shadowed areas beneath an architectural canopy. None of the existing scissor linkages composed of basic translational, polar, and angulated units in the literature moves along this trajectory precisely. Only polar linkages approximate the desired route despite their large deviations. The generalized scissor linkage (GSL) introduced in the paper with distinct parameters demonstrates fewer deviations. Hence, an attempt is made to synthesize the GSL as the optimized version of the polar linkages. The mathematical foundation of the optimization method is introduced. It is foreseen that this method holds the potential to evolve into a versatile design tool in the future. [ABSTRACT FROM AUTHOR]

Shape‐morphing structures capable of significantly altering shape and volume play a crucial role in diverse applications, ranging from soft robotics to minimally invasive surgery, deployable structures, and space exploration. This article presents an approach to achieve simple and controllable morphing onto multiple stable complex 3D surfaces—a long sought after goal in the field. The method is based on interconnected multistable straw‐like deformable tubes, constrained by rigid links that can be assembled and connected in many different ways. By leveraging the director‐field theory, the links and their assembly process are modeled and designed to reach a variety of desired final operational shapes from a single base‐structure. The use of viscous‐fluid actuation enables precise control and predictable shape‐morphing while facilitating a wide range of configurations through inflation and deflation sequences, all with a single input. [ABSTRACT FROM AUTHOR]

As the number of small satellites in low-Earth orbit increases, the goal of shortening the deorbit period after the end of operation has been set. Along with this trend, a more effective deorbit system than used to date is required. This paper proposes a deorbit component that combines a method of obtaining plasma drag by interference between on-orbit plasma and an electromagnetic field generated by an electromagnetic coil in a small satellite, and a method of obtaining air drag using deployable membranes. The proposed component uses a deployable membrane structure with electromagnetic coils, and it is possible to mount multiple components on a small satellite. It is possible to obtain greater drag using multiple components. In this paper, the plasma drag is calculated using the two-dimensional Full-Particle-In-Cell method when multiple deorbit components are mounted, and the appropriate coil arrangement is clarified. Furthermore, the deorbit duration is calculated by the total drag of the plasma drag and the air drag, and the performance of the proposed deorbit component is evaluated. [ABSTRACT FROM AUTHOR]

The emergence of mechanical metamaterials from 4D printing has paved the way for developing advanced hierarchical structures with superior multifunctionalities. In particular, 4D-printed mechanical metamaterials exhibit extraordinary mechanical performance by integrating multiphysics stimuli with advanced structures when actuated by external factors, thereby altering their shapes, properties, and functionalities. This critical review offers readers a comprehensive overview of the rapidly growing 4D printing technology for developing novel mechanical metamaterials. It provides essential information about the multifunctionalities of 4D-printed mechanical metamaterials, including energy absorption and shape-morphing behavior in response to physical, chemical, or mechanical stimuli. These capabilities are key to developing smart and intelligent structures for multifunctional applications such as biomedical, photonics, acoustics, energy storage, and thermal insulation. The primary focus of this review is to describe the structural and functional applications of mechanical metamaterials developed through 4D printing. This technology leverages the shape-shifting functions of smart materials in applications such as micro-grippers, soft robots, biomedical devices, and self-deployable structures. Additionally, the review addresses current progress and challenges in the field of 4D-printed mechanical metamaterials. In conclusion, recent developments in 4D-printed mechanical metamaterials could establish a new paradigm for applications in engineering and science.

The use of diagonalised modules is one of the techniques for converting a deployable structure into a bistable one. The layout of these modules is complicated by the fact that the geometric incompatibility must be sufficient in the service phase of the structure without structural failure during deployment. The text attempts to facilitate this harmonisation work. The folding process of both cuboid and pyramidal frustum diagonalised modules is analysed, and the different situations that occur are established. The geometric incompatibilities of the different modules proposed and of some variants and their evolution during the folding process are studied. A mechanical analysis is carried out based on dynamic calculations of the bending process of the different models studied. A set of graphs are obtained which reflect the evolution of the internal forces (axial forces and bending moments) of the different elements of the module throughout the process, as well as the elastic energy of the module, which are contrasted with those obtained geometrically and with several kinematic models carried out. The text identifies a range of recommended geometric incompatibilities and provides a control method for the design of pyramidal frustum modules. [ABSTRACT FROM AUTHOR]

Fascinating 3D shapes arise when a thin planar sheet is folded without stretching, tearing or cutting. The elegance amplifies when the fold/crease is changed from a straight line to a curve, due to the association of plastic deformation via folding and elastic deformation via bending. This results in the curved crease working as a hinge support providing deployability to the surface which is of significant interest in industrial engineering and architectural design. Consequently, finding a stable form of curved crease becomes pivotal in the development of deployable structures. This work proposes a novel way to evaluate such curves by taking inspiration from biomimicry. For this purpose, growth mechanism in plants was observed and an analogous model was developed to create a discrete curve of fold. A parametric model was developed for digital construction of the folded models. Test cases were formulated to compare the behavior of different folded models under various loading conditions. A simplified way to visualize the obtained results is proposed using visual programming tools. The models were further translated into physical prototypes with the aid of 3D printing, hybrid and cured-composite systems, where different mechanisms were adopted to achieve the folds. The prototypes were further tested under constrained boundary and compressive loading conditions, with results validating the analytical model. [ABSTRACT FROM AUTHOR]

Purpose: The most important need after natural disasters is the sheltering. However, most of the existing temporary shelters do not meet all requirements for long-term use and not provide adequate flexibility within the space. This paper aims to develop a transitional postdisaster shelter transforming from a closed shape to an expanded form in response to changing functional and spatial needs of disaster victims. The study also proposes alternative unit combinations for various functions, and settlement layouts to create a comfortable living environment for occupants. Design/methodology/approach: The research methodology is based on theoretical and design frameworks which requires inductive and deductive approaches. Forming the background of the study, the theoretical framework consists of four parts which are literature review on temporary shelters presenting state-of-the-art; determination of design guidelines and strategies based on shelter standards; identification of technical requirements; and analysis of existing temporary shelters. Having three parts, the design framework includes design of transformable transitional shelter based on three-dimensional modeling, creation of different unit combinations to be used for various purposes and development of settlement layouts as case studies. Findings: The analysis conducted in this study demonstrates that most of the existing temporary shelters have limited geometric configurations and major problems in terms of their performance, transportation and storage. On the other hand, the transformable shelter proposed by the authors can provide form and spatial flexibilities thanks to its expansion properties, occupy less space for transportation, easily be transported to any desired location in its compact state and be customized according to user needs. Several units can be combined either to serve larger families or to be used for different functions. Originality/value: This paper contributes to the literature as presenting not only a theoretical framework on temporary shelters but also a design framework on transformable shelter design for the ones who are willing to develop similar transformable shelters based on the determined guidelines, strategies and requirements. [ABSTRACT FROM AUTHOR]

Shape‐morphing structures capable of significantly altering shape and volume play a crucial role in diverse applications, ranging from soft robotics to minimally invasive surgery, deployable structures, and space exploration. This article presents an approach to achieve simple and controllable morphing onto multiple stable complex 3D surfaces—a long sought after goal in the field. The method is based on interconnected multistable straw‐like deformable tubes, constrained by rigid links that can be assembled and connected in many different ways. By leveraging the director‐field theory, the links and their assembly process are modeled and designed to reach a variety of desired final operational shapes from a single base‐structure. The use of viscous‐fluid actuation enables precise control and predictable shape‐morphing while facilitating a wide range of configurations through inflation and deflation sequences, all with a single input.

Carbon fiber reinforced polymers are widely used to manufacture aerospace deployable structures. These structures are folded in launch configuration and then deployed in space for operational activities. Since the stowage of deployable structures in folded configuration occurs for long time, the understanding of the viscoelastic properties of the material is essential to predict the structural behavior during both the deployment phase and the operational life. In this work, numerical relaxation analysis is performed on the representative volume element (RVE) of a carbon fiber reinforced polymer using a homogenization approach at the microscale. This aims to predict the effects of matrix viscoelasticity on the structural performance of a deployable structure. [ABSTRACT FROM AUTHOR]

Kinetic structures have gained popularity in architecture and structural engineering due to their ability to meet environmental factors and user needs. Among these structures, kinetic roof structures hold an important place, as they are deployable and/or transformable structures that can change their forms between two or more different geometries. Various categorizations of kinetic roofs based on their material, mechanism, and geometry have been offered in the literature. However, in most studies, they are placed under the broader category of kinetic structures. This paper critically reviews existing classifications of kinetic roofs, highlighting their advantages and limitations. Subsequently, a novel detailed classification system for kinetic roof structures is proposed. The superiority, advantages, and shortcomings of this proposed classification are presented. A more comprehensive and tailored classification system for kinetic roofs is provided by this study, contributing to the literature in this area.

Temporary houses are needed for the rehabilitation phase, which emerges a few weeks after the disaster and lasts until the finish of permanent houses. It is practically difficult to construct temporary houses in a short period. In particular, there are technical problems related to the logistics and installation speed. Therefore, the deployability feature, which can speed up the process, comes to the fore in this context. In this study, three examples with different deployment directions, which could be deployed in one, two and four directions, were examined regarding their capacity, storage and transportation, area per user and effective land utilization. Selected examples from the literature were compared according to the performances. As a result of this study, each example came to the fore in different performances. In this way, the advantages and disadvantages of each system were shown.

Baffles in optical systems on a satellite, such as imaging payloads and star trackers, involve structures with large empty volumes that take up significant payload volume. Limiting the volume of optical systems is essential, considering the demand for small satellite platforms and rideshare launch missions. A baffle structure with empty volume can be configured to stow in a packed configuration during launch and deploy to its operational configuration once the satellite is in orbit. An analytical model for deployable conical baffles is developed to trade off various design parameters. A simple and reliable deployment mechanism with large torsion springs is designed and developed for an optical baffle. A prototype baffle is developed with representative materials, and functional testing is carried out. The deployment tests were carried out to measure the shocks and deployment accuracy. The baffle in its stowed configuration performed satisfactorily and indicated no damages when subjected to vibration testing. Further, the deployment mechanism performed adequately at a low temperature of −40 °C and at 0.062 mPa during the cold functional test in a thermovac chamber. The baffle is a precursor to the flight model, which will be launched as a part of a hyperspectral imager, CyanoSat of CSIRO. [ABSTRACT FROM AUTHOR]

Ring origami has emerged as a robust strategy for designing foldable and deployable structures due to its impressive packing abilities achieved from snap-folding. In general, polygonal rings with rationally designed geometric parameters can fold into compact three-loop configurations with curved segments which result from the internal bending moment in the folded state. Inspired by the internal bending moment-induced curvature in the folded state, we explore how this curvature can be tuned by introducing initial natural curvature to the segments of the polygonal rings in their deployed stress-free state, and study how this initial curvature affects the folded configurations of the rings. Taking a clue from straight-segmented polygonal rings that fold into overlapping curved loops, we find that this behavior can be reversed by introducing curvature into the ring segments in the stress-free initial state such that the rings fold into a looped straight-line configuration with "zero" area. This strategy realizes extreme packing of the rings. In this work, by a combination of experimental observation, finite element analysis, and theoretical modeling, we systematically study the effect of segment curvature on folding behaviors, folded configurations, and packing abilities of curved ring origami with different geometries. It is anticipated that curved ring origami can open a new avenue for the design of foldable and deployable structures with simple folded configurations and high packing efficiency. [ABSTRACT FROM AUTHOR]

Reflector antennas, operating at high frequencies, require a high surface accuracy: deviations from the target geometry accuracy result in a loss of RF performance (e.g., antenna gain and efficiency). As a result, the aperture may need to be larger, or a more complex backing structure must be engineered to achieve the reflector surface accuracy to deliver the equivalent gain of an efficient solid reflector. This would typically increase the mass, the stowed volume, and the design complexity. The design of larger aperture deployable antennas (e.g., Cassegrain, Offset) for SAR (Synthetic Aperture Radar) applications can be challenging for missions where platform size and payload mass are limited. Inspired by the Origami based techniques, Oxford Space Systems (OSS) is currently developing an innovative SAR Reflectarray antenna, targeting the X-Band frequency range, with the aim of achieving a relatively large aperture from a small, stowed volume suitable for a small satellite. The Reflectarray antenna architecture has several potential advantages over other antenna designs. It is a cost-competitive technology with excellent stowage efficiency, which can be further improved with origami-based folding mechanisms/kinematics. It requires a simplified deployment mechanism and in contrast to conventional parabolic reflectors, it does not need a separate backing structure. Until now, work on space deployable Reflectarray antennas (e.g., MARCO, OMERA and ISSARA missions from NASA) have focused on multi-degree of freedom structures, i.e., independent self-actuated hinge driven architectures. This paper presents an elegant single degree of freedom, origami-inspired Reflectarray architecture that does not require actuation on all the hinges. Thanks to its Hold-Down Release Mechanism (HDRM) and spring-loaded hinges, the OSS Reflectarray antenna is self-deployable. It maintains the required flatness accuracy achieved through its novel hinge integrated latching system. The OSS Reflectarray antenna has an 8:1 footprint stowage ratio, which enables installation on small satellite platforms (between 50 kg and 100 kg). The reflectarray has been designed to work in the X-band frequency with dual linear polarization for the concept study. However, the architecture can be scaled up or down to suit other frequency bands, making the OSS Reflectarray compatible with many applications and platforms. • Rigid origami folding ensure high deployed/stowed volume ratio. • OSS Origami Reflectarray design ensure high Performances/mass ratio. • OSS Reflectarray simulations results ensure a good correlation with tests. • Target for SAR applications in the design. • Kinematics and RF tests successfully prove the design of such antenna. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

While 3D printing enables the customization and home fabrication of a wide range of shapes, fabricating freeform thin-shells remains challenging. As layers misalign with the curvature, they incur structural deficiencies, while the curved shells require large support structures, typically using more material than the part itself. We present a computational framework for optimizing the internal structure of 3D printed plates such that they morph into a desired freeform shell when heated. This exploits the shrinkage effect of thermoplastics such as PLA, which store internal stresses along the deposition directions. These stresses get released when the material is heated again above its glass transition temperature, causing an anisotropic deformation that induces curvature. Our inverse design method takes as input a freeform surface and finds an optimized set of deposition trajectories in each layer such that their anisotropic shrinkage deforms the plate into the prescribed surface geometry. We optimize for a continuous vector field that varies across the plate and within its thickness. The algorithm then extracts a set of deposition trajectories from the vector field in order to fabricate the flat plates on standard FFF printers. We validate our algorithm on freeform, doubly-curved surfaces. [ABSTRACT FROM AUTHOR]

We introduce a computational pipeline for simulating and designing C-shells, a new class of planar-to-spatial deployable linkage structures. A C-shell is composed of curved flexible beams connected at rotational joints that can be assembled in a stress-free planar configuration. When actuated, the elastic beams deform and the assembly deploys towards the target 3D shape. We propose two alternative computational design approaches for C-shells: (i) Forward exploration simulates the deployed shape from a planar beam layout provided by the user. Once a satisfactory overall shape is found, a subsequent design optimization adapts the beam geometry to reduce the elastic energy of the linkage while preserving the target shape. (ii) Inverse design is facilitated by a new geometric flattening method that takes a design surface as input and computes an initial layout of piecewise straight linkage beams. Our design optimization algorithm then calculates the smooth curved beams to best reproduce the target shape at minimal elastic energy. We find that C-shells offer a rich space for design and show several studies that highlight new shape topologies that cannot be achieved with existing deployable linkage structures. [ABSTRACT FROM AUTHOR]

Tensegrity is composed of structures that are characterized by compressive elements (bars) and tension elements (cables) that work together to transmit and/or withstand forces in an efficient and balanced manner. Their kinetic analysis, design, and control are study topics with various methods still being explored. Furthermore, research and development have been conducted in different areas such as architecture, engineering, biomechanics and robotics, exploring lightweight and resilient tensegrity structures for more flexible and adaptable movements. Tensegrity is a structure increasingly used and studied in different areas, thanks to its ability to transmit forces efficiently and its versatility in the application of designs and solutions in different areas. So, this review presents initial definitions of this area, as well as recent methods and applications that have been developed and are the focus of study for future advances. [ABSTRACT FROM AUTHOR]

Shape memory epoxy polymer reinforced by single-ply weave fabric (SMEP-W) possesses high specific stiffness, good foldability, and satisfactory shape memory capability. These advantages make them promising materials for deployable space structures and increasingly attract research interests. Understanding the influence of weave structures on static and dynamic mechanical properties is crucial to structural design and mechanical response prediction. In this paper, a recently developed SMEP-W was prepared. The static shear experiments were conducted through modified shear test fixtures, and the stress field under static shear load was simulated through a multi-scale numerical modelling method. The dynamic mechanical analysis was carried out to evaluate the shape memory capability. SMEP-W shows nonlinear mechanical behavior under in-plane shear load, especially for the one with less thread count. The increase in the number of threads enhances the constraints between warp yarns and weft yarns, leading to an increase in shear modulus and reducing the scattering of static mechanical properties. The stress distribution on the yarns has the characteristic of center symmetry. High-stress regions appear on the overlapping surface of the crossover regions. Compared with shape memory epoxy polymer (SMEP), the glass transition temperature and damping coefficient of SMEP-W are significantly reduced, and the stiffness is remarkably enhanced. The difference in thread count between warp direction and weft direction does not notably affect the glass transition temperature and tan δ, but has a remarkable influence on the storage modulus. The present work could provide basic observation for understanding the influence of thread count on the shear mechanical properties and dynamic mechanical properties of SMEP-W. [ABSTRACT FROM AUTHOR]

Fascinating 3D shapes arise when a thin planar sheet is folded without stretching, tearing or cutting. The elegance amplifies when the fold/crease is changed from a straight line to a curve, due to the association of plastic deformation via folding and elastic deformation via bending. This results in the curved crease working as a hinge support providing deployability to the surface which is of significant interest in industrial engineering and architectural design. Consequently, finding a stable form of curved crease becomes pivotal in the development of deployable structures. This work proposes a novel way to evaluate such curves by taking inspiration from biomimicry. For this purpose, growth mechanism in plants was observed and an analogous model was developed to create a discrete curve of fold. A parametric model was developed for digital construction of the folded models. Test cases were formulated to compare the behavior of different folded models under various loading conditions. A simplified way to visualize the obtained results is proposed using visual programming tools. The models were further translated into physical prototypes with the aid of 3D printing, hybrid and cured-composite systems, where different mechanisms were adopted to achieve the folds. The prototypes were further tested under constrained boundary and compressive loading conditions, with results validating the analytical model.

The structural properties of deployable components on communications satellites—specifically, booms with different cross sections—are investigated. The principles of boom folding are outlined. The deformation of the boom profile is considered. Stability loss of the structure is studied. Promising directions for future research are noted. [ABSTRACT FROM AUTHOR]

Fully soft bistable mechanisms have shown extensive applications ranging from soft robotics, wearable devices, and medical tools, to energy harvesting. However, the lack of design and fabrication methods that are easy and potentially scalable limits their further adoption into mainstream applications. Herein, a top–down planar approach is presented by introducing Kirigami‐inspired engineering combined with a pre‐stretching process. Using this method, Kirigami‐Pre‐stretched Substrate‐Kirigami trilayered precursors are created in a planar manner; upon release, the strain mismatch—due to the pre‐stretching of substrate—between layers will induce an out‐of‐plane buckling to achieve targeted 3D bistable structures. By combining experimental characterization, analytical modeling, and finite element simulation, the effect of the pattern size of Kirigami layers and pre‐stretching on the geometry and stability of resulting 3D composites is explored. In addition, methods to realize soft bistable structures with arbitrary shapes and soft composites with multistable configurations are investigated, which may encourage further applications. This method is demonstrated by using bistable soft Kirigami composites to construct two soft machines: (i) a bistable soft gripper that can gently grasp delicate objects with different shapes and sizes and (ii) a flytrap‐inspired robot that can autonomously detect and capture objects. [ABSTRACT FROM AUTHOR]

Abstract The aim of this work is to analyze the effect of different materials on the folding of ultrathin tape spring hinges. This mechanism is modeled using the Finite Element Method (FEM) combined with the Carrera Unified Formulation (CUF) for the development of refined 2D shell models. These models can deal with different materials and different theoretical approximations can be introduced in an automatic way thanks to the hierarchical capability of the CUF formalism, according to which the degree of refinement of the mathematical model is an input to the analysis. The nonlinear governing equations are developed using a Total Lagrangian formulation and solved via a Newton-Raphson linearization technique with arc-length type constraints. A validation of the proposed model is carried out by comparing the results with those available in the literature involving a cured T300-1k/913 tow and HexPly 913 resin. After a convergence analysis, the mathematical model proves to ensure a good fit. This model is used for the final analysis with different materials, i.e. isotropic metallic with hardened steel tape spring and unidirectional T300 graphite fibre/epoxy prepreg with 34% resin content by weight. The results, in the form of moment angle curves, are reported for two different values of the thickness of the structure. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Architectural Sciences & Applications (JASA) is the property of Journal of Architectural Sciences & Applications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Architectural Sciences & Applications (JASA) is the property of Journal of Architectural Sciences & Applications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A new approach to model the microbuckling of fiber-reinforced soft composites under bending is presented, which takes into account large deformations of the matrix and nonlinear kinematics. It leverages recent advances from the field of nonlinear homogenization of fiber composites to model the response of the matrix under the three-dimensional loading observed during buckling. The model then calculates the strain energy of the system as a function of several parameters, such as the position of the neutral axis or the microbuckling wavelength, whose values are obtained through energy minimization. The moment-curvature relationship predicted by the model agrees with experimental results, particularly in the postbuckling regime. The predictions also capture the buckling wavelength, as well as the fact that microbuckling extends into the tension side for thin laminates, an experimental observation that contradicts kinematic assumptions in previous modeling efforts. A parametric study considering possible variations in the composite laminate shows strong trends for parameters, such as thickness and volume fraction. [ABSTRACT FROM AUTHOR]

In the present article, the geometrical nonlinear behavior of deployable booms undergoing large displacements and rotations is investigated. The triangular rollable and collapsible boom made of fiber-reinforced composite materials is considered along with a metallic tape spring. The mathematical model makes use of higher-order 1D structural theories based on the Carrera unified formulation, which allows the description of moderate nonlinearities to deep post-buckling mechanics of ultra-thin shells in a hierarchical and scalable manner. Particular attention is focused on the study of equilibrium paths of the booms subjected to coiling bending. Dedicated experimental tests reveal the validity of the proposed finite element approach, whereas the investigation of different lamination sequences offer a valuable perspective for possible future designs. [ABSTRACT FROM AUTHOR]

In recent years, in parallel to Earth Observation (EO) consolidating its role in space applications, spacecraft miniaturisation has been gaining increasing popularity. Smaller satellites represent the ideal platform for cost-effective and relatively quicker technology demonstrations. Furthermore, the perspective of high-volume production would simplify the design of constellations made of identical spacecraft in order to improve the revisit time. Optical payloads could be enhanced by using deployable systems based on carbon fibre-reinforced polymer (CFRP) tape-springs, which are very compact before deployment and highly stable in their extended configuration. In a previous work by the authors, an engineering model of a telescope intended for CubeSats was fabricated and tested. In this paper, the coefficients of thermal expansion (CTE) found experimentally by the authors were implemented in the Finite Element (FE) model via the mathematical framework of the Classical Laminated Plate Theory (CLPT). Thermally-induced distortions of the deployed telescope were analysed numerically for different illumination conditions in low-Earth orbits. The orientation of the assembly with respect to the radiation was found particularly critical. An uncertainty analysis that took into account composite material properties errors was carried out. The results indicated that the predicted response lies in a wide range of uncertainty, which can be detrimental regarding the fulfilment o mission requirements. The impact of different thermal control finishes was evaluated, and the overall response over the spacecraft lifetime was heavily affected by absorptivity degradation. Alternative cross-sections rather than semi-circular tape-springs were implemented in the model, although the increased bending stiffness mainly affected the temperature distribution and showed only a minor impact on the deformations. • Novel design for a deployable space telescope based on CFRP tape springs. • Numerical thermo-structural analysis in LEO thermal environment. • Implementation of CTE found experimentally into FE model. • Uncertainty analysis of the thermally-induced deformations. • Analysis of the impact of different coating and cross-sections. [ABSTRACT FROM AUTHOR]

Two dimensional nature of thin membranes has led to their evolution as an essential component in space structures that demand lighter mass and compact packaging. Origami based folding patterns are used to fold these membranes into compact configurations by introducing plastic deformations along the predetermined fold-lines referred to as creases. Creases have been observed to alter the material state and the mechanical response of highly compacted thin membranes, leading to changes in their deployment behaviour outer space. This paper proposes an idealised connector element based method which introduces rotational stiffness associated with the creases while eliminating the requirement for a large number of small shell elements to capture accurate deployment behaviour. First, an experiment is carried out to quantify the fold-line rotational stiffness of Kapton polyimide film. Then, the technique is implemented in a commercially available finite element package ABAQUS simulating the deployment of a single-folded thin membrane, and is identified to capture in-plane and out-of-plane displacements with a better approximation than the other existing crease modelling techniques. Then the applicability of the proposed technique is validated against a quasi-static deployment experiment of a solar sail model available in the literature. The use of the proposed technique has proven to be qualitatively effective in terms of inducing a quasi-static deployment that achieves fair quantitative agreement as well. [ABSTRACT FROM AUTHOR]

Compliant deployable mechanisms (CDMs), as a novel and promising type of mechanisms, have been gradually used in medical industry, aerospace and other engineering fields that require high space utilization and compactness. Therefore, it is necessary to develop a general and efficient methodology to design and analyze CDMs. This paper proposes a general framework for designing and analyzing CDMs. The proposed framework has been verified by finite element method (FEM) first. Then, for practical validation, we design two types of compliant deployable mechanisms for different application scenarios within this framework, and experimental testing has been conducted to prove the feasibility of the proposed framework. Compared to the existing methods for designing CDMs, this framework demonstrates a more general scheme where different engineering scenarios can be taken into account to meet the design requirements, presenting several desired advantages over the existing methods, such as higher accuracy and less computational expense. • We propose a general framework for designing compliant deployable mechanisms (CDMs). • The framework also has the advantages of high accuracy and low calculation costs. • We present two types of CDMs to provide feasible schemes for future applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Studying 4D printed-based mechanical metamaterials systematically. • Reviewing multifunctional energy-absorbing and shape-morphing features. • Outlining applications of 4D printed-based mechanical metamaterials. • Discussing multifaceted challenges with proposed solutions. The emergence of mechanical metamaterials from 4D printing has paved the way for developing advanced hierarchical structures with superior multifunctionalities. In particular, 4D-printed mechanical metamaterials exhibit extraordinary mechanical performance by integrating multiphysics stimuli with advanced structures when actuated by external factors, thereby altering their shapes, properties, and functionalities. This critical review offers readers a comprehensive overview of the rapidly growing 4D printing technology for developing novel mechanical metamaterials. It provides essential information about the multifunctionalities of 4D-printed mechanical metamaterials, including energy absorption and shape-morphing behavior in response to physical, chemical, or mechanical stimuli. These capabilities are key to developing smart and intelligent structures for multifunctional applications such as biomedical, photonics, acoustics, energy storage, and thermal insulation. The primary focus of this review is to describe the structural and functional applications of mechanical metamaterials developed through 4D printing. This technology leverages the shape-shifting functions of smart materials in applications such as micro-grippers, soft robots, biomedical devices, and self-deployable structures. Additionally, the review addresses current progress and challenges in the field of 4D-printed mechanical metamaterials. In conclusion, recent developments in 4D-printed mechanical metamaterials could establish a new paradigm for applications in engineering and science. [ABSTRACT FROM AUTHOR]

Tape-springs – straight strips with transversely curved cross-sections – undergo a flattening of the cross-section upon bending, and accompanying torsional buckling in equal-sense bending which then "recedes" at greater deformation. The exact analytical solution for tape-spring bending was solved by Mansfield; however, the resulting expression for the twisting curvature at the onset and recession of torsional buckling cannot be solved in closed-form. Approximate closed-form expressions are therefore sought: firstly, by utilising Taylor series approximations of Mansfield's extensive functions; and secondly, by assuming a uniform transverse curvature, thereby rendering the problem algebraic in nature, and deriving new governing expressions. Further approximations assume the cross-section does not deform upon bending, and that the tape-spring remains a developable surface in the inextensible limit of zero thickness. All approximate solutions are shown to agree closely with Mansfield's solution at small curvatures, with the uniform curvature approximation also capturing the recession of torsional buckling to a reasonable degree of accuracy. The accuracy of the uniform curvature approximation is related to a pertinent dimensionless parameter, which governs the size of a boundary layer in Mansfield's exact solution: as this parameter tends to infinity, the uniform curvature approximation and Mansfield's exact solution are shown to converge; as it tends to zero, all solutions are shown to converge on the inextensible limit. • Approximate solutions for tape-spring bending assuming uniform curvature. • Closed form expressions for the onset and recession of torsional buckling. • Approximate solution in good agreement with exact Mansfield solution. • Exact and approximate solutions converge in the zero-thickness inextensible limit. [ABSTRACT FROM AUTHOR]

• Multiscale FE modeling of origami inspired dual-matrix deployable composite fold is presented. • Elasto-plastic and hyper-viscoelastic behavior of dual-matrix origami fold is characterized and modeled. • The effect of the rate of folding and stowage time on residual curvature and deployment behavior is investigated. • The time required for complete deployment are reported for fold and full scale structure. Dual matrix deployable composites with viscoelastic materials are prone to experiencing relaxation in their stored strain energy, leading to potential degradation in their deployment performance. This study presents a multiscale FE modeling approach to investigate the folding and deployment behavior of origami inspired dual-matrix deployable composite with visco-hyperelastic hinge. A typical dual-matrix origami composite fold was manufactured using a hot compression molding technique and hand layup method and folding tests were carried out. The visco-hyperelastic behavior of elastomer used in the folding region was characterized. Experiments were carried out on elastomer under rate dependent loading, single-step, multi-step, and cyclic tests and material parameters for constitutive model were identified. The homogenized properties of hybrid laminate and elastomer laminate were obtained from XCT-driven FE based homogenization of real RVE. First, the multiscale FE model was validated with the experimentally-measured moment-curvature diagram. Next, the proposed multiscale FE model was employed to simulate the influence of modulus relaxation of pure elastomer on the deployment behavior of a simple rectangular fold and an origami-inspired waterbomb base structure. The variation of moment-curvature, and relaxation in strain energies during stowage under controlled and free deployment are reported. The effect of incomplete folding and stowage durations on strain energy and deployment time was investigated. In the end, the influence of the loading rate effect on the bending stiffness relaxation of pure elastomer and elastomer laminate fold was investigated. [ABSTRACT FROM AUTHOR]

Soft robots are advantageous for human interaction owing to their adaptability and safe interactivity. However, research on soft robots is challenging because of the complex fabrication process of elastomeric materials with multiple channels. In this study, we introduce a prototyping technique for the fabrication-friendly soft robots using pneumatic artificial muscle(PAMs) and modular 3D printed reinforcement. We presented three primitive deformation structures: bending, twisting, and contraction. Moreover, we propose a novel variable stiffness technique that alters PAMs contraction and radial expansion behavior into locking, malleable, and rotational brake features. We explore both the parallel and series arrangement of the reinforcement module and propose new types of mixing configurations and scaling techniques. We quantitatively verified the force scaling technique on different types of features. We demonstrate the feasibility of this prototyping technique through six application examples and conclude with a discussion of the limitations and possible future improvements.

Foldable structures have been of great interest due to their ability to reduce in size from deployed to folded state, enabling easier storage in scenarios with space constraints such as aerospace and medical applications. Hexagonal structural components have been of interest, due to their ability to tessellate, or cover without gap, 2D and 3D surfaces. However, the study on effective folding strategies for hexagon-based structures and the hexagon geometry itself is limited. Here, we report a strategy of snap-folding hexagonal rings, to result in folded states with only 10.6% the initial area of a single ring. Motivated by this significant packing, we utilize a combination of experiments and finite element analysis to study effective folding strategies and packing abilities of various 2D and 3D hexagonal ring assemblies, with structures that can be folded to 1.5% and 0.4% of their initial area and volume, respectively. The effect of geometric parameters of hexagonal rings on the mechanical stability of their assemblies is investigated. Additionally, the instabilities of rings can be utilized to facilitate the automatic deployment of folded ring assemblies under small perturbations. Furthermore, an assembly with rigid functional panels is explored to demonstrate the functionality and design space for hexagonal ring assemblies. With such significant demonstrated area and volume changes upon snap-folding, it is anticipated that hexagonal ring assemblies could inspire future aerospace or biomedical designs, where reconfiguration and large packing are required. [ABSTRACT FROM AUTHOR]

Consisting of linear elements, reciprocal frame structures are three-dimensional (3D) self-supported structures that can be rapidly assembled. This feature renders them suitable for both temporary and permanent uses. Considered as a type of deployable frame, such structures can be used in architectural and engineering applications. As a subset of reciprocal frame structures, rotegrity structures can be advantageous, owing to their structural form. In this work, a spherical rotegrity structure is constructed on a geodesic sphere through its transformation to a reciprocal structure with mutually supporting elements. Instead of the bolted connections commonly used in practice, a notched connection is proposed to facilitate the construction process of the self-supporting rotegrity structure. The parametric modeling of the rotegrity structure is created in Grasshopper, and two prototypes, having circular and rectangular cross sections, are built. In each prototype, two sets of elements, called Type A and Type B, are used, the linear member lengths and cross sections of which are identical. The cross sections of the members of the two prototypes are different. To assemble the prototypes, first, a number of elements are fabricated through 3D printing and tested in terms of their self-supporting capabilities and connections. Then, stainless steel pipes and wooden bars are used for Prototypes I and II, respectively. It is found that Prototype I, composed of circular hollow section profiles, is unstable, owing to the rotation of elements and because it requires the use of stabilizers. Conversely, Prototype II, which consists of rectangular cross-section elements, becomes stable when the last element is installed in the right place and did not require any additional attachment. [ABSTRACT FROM AUTHOR]

This paper provides a review of early development studies on structures carried out by NASA and US aerospace contractors between 1975 and 1985 before and during the initiation of the Space Station programme. The studies envisioned very large structures built in orbit using the Space Shuttle, then in the process of entering service. Their original purpose was to function as solar power, antenna and communications platforms. The studies explored the application of automatically-fabricated trusses, then preassembled deployable trusses, and then astronaut-assembled erectable trusses. By the time of the Station's go-ahead in 1984, a large erectable truss structure formed the backbone of the Station's design. Erectable trusses were successfully tested on a Space Shuttle mission in 1985 but later abandoned after the Shuttle Challenger disaster in 1986. Taken together, the 1975–1985 development studies have much historical significance as the first generation of ideas about large engineered structures for extraterrestrial applications. [ABSTRACT FROM AUTHOR]

Due to their expansion capabilities and the simplicity of their design, scissor linkages have been used in both architecture and engineering for various applications, such as expandable roofs and shelters, movable bridges, furniture, and as parts of mechanisms. The two main design methods used for scissor linkages are the unit-based method and the loop-based method. While the unit-based method is based on serial multiplication of the scissor units, the loop-based method is based on aligning predefined loop types onto the desired curve. When the input parameter is the desired curvature for the finally deployed configuration of the linkage, the loop-based method is easier and more convenient for defining the scissor units to create the whole linkage geometry. Most of the existing studies on the loop-based method deal with identical or arbitrary loops. Hybrid loop assemblies have not yet been studied, although they may offer different geometric alternatives. This work aimed to fill this gap in the literature and present a geometric design approach for scissor linkages composed of hybrid loop assemblies using frieze patterns. First, the basic terminology, such as loop types, loop assemblies, and frieze patterns, is introduced. Then, we discuss scissor linkages using hybrid loops, generated using a predefined rectilinear geometry in which frieze groups are used to provide diverse variations. The kinematic definitions of the represented linkages are then explained. To reveal the potential applications of the scissor linkages composed of hybrid loops, a case study was conducted in which the proposed linkages were used as a canopy structure. After discussing the potential for using hybrid loops, and their deployment, we present the concluding remarks and make suggestions for future research. [ABSTRACT FROM AUTHOR]

Classification and development of the deployable structures is an ongoing process that started at the end of 20th century and is getting more and more attention throughout 21st. With the development of the technology, constructive systems and materials, these categorizations changed – adding new typologies and excluding certain ones. This work is giving a critical review of the work done previously and on the change of the categories. The special interest is given to the pantographs (or scissor structures) and the Zeigler’s dome as the form of their application. It is noticeable that after its introduction in 1977, the dome was a part of the initial classification, but with the time it lost its place. The reason for this is the introduction of more efficient scissor dome structures. However, perhaps with the use of data-driven design, this dome can be optimized and become relevant again.

Origami-inspired folding possesses great potential to create deployable structures through folding and unfolding along the crease lines. Easy deployment, one of the many attractive attributes of deployable structures, also indicates the structure can be collapsed easily under loading without locking devices. In this paper, a deployable supporting structure inspired by Kresling origami pattern with "easy deploy and hard collapse" characteristic is presented. This supporting structure can be collapsed along two different paths from the deployment state. One path with high stiffness is chosen to fulfill the demand of hard collapse as supporting structure yields load-bearing capability. Another path with zero stiffness by introducing variable kinematic joints into the legs of the structure is selected to achieve the function of easy deployment, which transforms the supporting structure to a deployable/foldable mechanism. Static stiffness of the supporting structure and kinematics and dynamics of the deployable/foldable mechanism are analyzed. The principle in this work can be utilized to design and create versatile origami-inspired deployable supporting structures that can find many applications. • A deployable supporting structure inspired by Kresling origami pattern is presented. • Stiffness optimization of the supporting structure is fulfilled based on one-sheet hyperboloids theory. • Selective and easy deployability is analyzed by using energy landscapes and dynamic simulations. [ABSTRACT FROM AUTHOR]

Due to the inherent viscoelasticity of constituent matrix and the possibility of long-term storage, space deployable structures made of composites are likely to exhibit relaxation in the stored strain energy, which may degrade their deployment performance. This paper presents a bottom-up finite element based multiscale computational strategy that bridges the experimentally measurable properties of constituent fibers and matrix to numerical predictions of viscoelastic behavior of composite laminates and general shell structures. A user-friendly RVE analysis plug-in tool is developed in Abaqus/CAE to rapidly estimate the effective orthotropic viscoelastic properties of unidirectional composites by taking as input the microstructure geometry as well as the known properties of fibers and matrix. Some benchmark problems were solved, and the accuracy and efficiency of the proposed plug-in tool were verified. Next, the strategy is shown to be applicable to model the viscoelastic behavior of macroscale composite laminates and deployable shell structures, by utilizing built-in functions in Abaqus to define the stacking sequence and accordingly update the material properties. In particular, the proposed multiscale strategy was employed to simulate the influence of modulus relaxation on the deployment dynamics of a composite tape-spring hinge, and good agreement was achieved as compared to reported experimental results.

This paper studies the folding of square, kirigami-inspired space structures consisting of concentrically arranged modular elements formed by thin shells. Localized elastic folds are introduced in the thin shells and different folding strategies can be obtained by varying the location of the folds and the sequence of imposed rotations. Modeling each modular element with rigid rods connected by revolute joints, numerical simulations of the kinematics of folding are obtained, including constraints that represent folding aids and a gravity offload system. These simulations are used to study two specific packaging schemes, and the folding envelopes of a specific structure are analyzed to identify the scheme that is easier to implement in practice. This particular scheme is demonstrated by means of a physical prototype. • We study the folding of space structures consisting of concentric modular elements. • Different packaging schemes are obtained by varying the locations of localized elastic folds. • A numerical model, based on rigid rods with revolute joints, is used to simulate the folding kinematics. • Specific packaging schemes that can be achieved with simple folding aids and gravity offloads are studied. • The scheme that is easier to implement is selected for an experimental demonstration. [ABSTRACT FROM AUTHOR]

Flat arrays consisting of panels of finite thickness are widely used in aerospace applications such as solar panels and reflectarray antennas. Packaging them into compact bundles without any voids and then deploying them bi-directionally to flat, continuous and accurate surfaces with a single degree of freedom (DoF) has challenged engineers for decades. Here, we present a solution based on origami of thick panels. In modular construction, we first created two deployable unit arrays, each of which comprises four eight-panel elements where panels in regular shapes are connected by simple but robust rotational joints. We prove that these units have only a single DoF, and they can be folded from a flat array to compact bundles without any voids. We then show that the units can be tessellated to form larger flat arrays where a single-DoF deployment and compact packaging properties are intact. A parametric study is carried out, which provides a precise design range that prevents the panels from physical interference during deployment. Physical models were constructed that have successfully validated the concepts. Our work is directly applicable to the design of future flat arrays that can be controlled with ease. [ABSTRACT FROM AUTHOR]

Reconfigurable structures have attracted increasing attention in numerous fields, such as aerospace, biomechanical, and civil engineering, owing to their nature to reshape and readjust without altering their original architectures. However, one of the most challenging issues in designing a reconfigurable structure is to ensure a load‐bearing capacity after reconfiguration, while keeping the structural flexibility during the transformation process. Here, an origami tube that can be easily reconfigured into multiple shapes, yet offering a stiffening mechanism for load‐bearing purposes is presented. A complete set of possible configurations that a single design can be reconfigured into is mathematically identified and classified. Significant differences in their axial stiffness for various configurations are analytically and experimentally investigated. Lastly, a self‐reconfiguring and stiffening mechanism of the proposed origami tube structure made with shape memory polymer (SMP), which automatically reinforces its axial stiffness about an order of magnitude through kinematic transitions is demonstrated. [ABSTRACT FROM AUTHOR]

Soft actuators are favored due to their flexibility and adaptability, but are limited to single actuation mode. Herein, a novel soft actuator with a dual‐kinestate performance is proposed. By subtly integrating a bistable compliant mechanism with artificial muscles, the soft actuator is capable of switching between binary motion and continuous motion with accurate output. Functions of overcoming external interference and regulating the snapping time are realized with programmed voltages. Two applications utilizing the switchable kinestate are illustrated, including a mechanical encryption display system with one actuator and an amplitude modulation system with two actuators in parallel. This novel soft actuator exhibits potential applications for the multi‐mode actuation of soft robots. [ABSTRACT FROM AUTHOR]

Bias deployable structural units are two-way structures arranged in a rotational pattern with respect to the edges. They have interesting advantages such as robust three-dimensional operation with supports around their entire base perimeter and the exclusive use of load-bearing scissor-like elements (SLEs). However, they do not have edge trims and their resistance to angular distortion is limited. This article proposes a series of deployable bi-stable structures that address these problems and incorporate new, resilient features. A method of analysing the incompatibilities of the structural unit is developed based solely on the geometric study of the deployment process, which allows the level of incompatibility of the proposal to be graduated, varying from stress-free structures to bi-stable structures. A kinematic model of one of the proposals allows the research undertaken to be contrasted. [ABSTRACT FROM AUTHOR]

Scissor linkages have been used for several applications since ancient Greeks and Romans. In addition to simple scissor linkages with straight rods, linkages with angulated elements have been introduced in the last decades. In the related literature, two methods have been used to design scissor linkages, one of which is based on scissor elements, and the other is based on assembling loops. This study presents a systematic classification of scissor linkages as assemblies of rhombus, kite, dart, parallelogram and anti-parallelogram loops using frieze patterns and long-short diagonal connections. After the loops are replicated along a curve as a pattern, the linkages are obtained by selection of proper common link sections for adjacent loops. The resulting linkages are analyzed for their motions and they are classified as realizing scaling deployable, angular deployable or transformable motion. Some of the linkages obtained are novel. Totally 10 scalable deployable, 1 angular deployable and 8 transformable scissor linkages are listed. Designers in architecture and engineering can use this list of linkages as a library of scissor linkage topologies. [ABSTRACT FROM AUTHOR]