Spring Hinge Research Articles

Optimization of DLTS Hinges for the Assembly of the Solar Arrays of a Communication CubeSat

This paper demonstrates the analytical and numerical investigations for the obtainment of the predefined critical parameters of double-layer tape spring (DLTS) hinges. The DLTS hinge is utilized for the coupling between the solar panels to assist the accommodation and formulation of the assumed origami-based pattern of the solar arrays. They are examined for the assurance of safety, durability, non-permanent deformation, and stability from the stowed to the deployment configuration. Von Misses stress (σv) and steady-state moment simulations are investigated by varying the critical hinge design parameters of curvature radius (R), subtended angle (θ) and layer thickness (t). Two optimization models, Taguchi and response surface methodology/RSM, are utilized by employing the computational findings to obtain and validate the modified optimal geometric parameters within this analytical experiment. For the Taguchi method, the optimization of σv and the steady-state moment is accomplished with a t of 1.75–2.25 mm, R of 1.5–2.0 mm, and θ of 1–1.2°. Furthermore, the RSM model shows that the t, R, and θ parameters are determined to be 2.90 mm, 2 mm, and 1.35°, respectively. For optimization of the hinge design, both models should be considered for improved verification and accuracy of the results.

Modeling and Disturbance Analysis of Spinning Satellites with Inflatable Protective Structures

The escalating proliferation of space debris poses an increasing risk to spinning satellites, elevating the probability of hazardous collisions that can result in severe damage or total loss of functionality. To address this concern, a pioneering inflatable protective structure is employed to ensure the optimal functionality of spinning satellites. Additionally, a multi-body dynamic modeling method based on spring hinge unfolding/spring expansion is proposed to tackle the complex dynamics of spinning satellites with inflatable protective structures during flight. This method enables analysis of the motion parameters of spinning satellites. First, the structural composition of a spinning satellite with inflatable protective structures is introduced and its flight process is analyzed. Then, an articulated spring hinge unfolding model or a spring expansion model using the Newton–Euler method is established to describe the unfolding or expansion of the spinning satellite with inflatable protective structures during flight. Finally, the effects on the motion parameters of a spinning satellite are analyzed through simulation under various working conditions.

Effect of different material on the folding of composite ultrathin tape spring hinges via unifed 2D shell models

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.

Folding a flat rectangular plate of uniform-thickness panels using Miura-ori

In the realm of space technology, aerospace solar arrays are conventionally employed as efficient means of energy harvesting. The solar arrays need to be packaged in a payload capsule before launch and unfold as a standard rectangle with uniform thickness and a flat surface in orbit. In this paper, we introduce a novel methodology for folding a standard rectangular plate with uniform thickness and a flat surface based on Miura origami. Importantly, these plates can be unfolded with a single degree of freedom after a special design. The package direction is defined by analyzing the distinct characteristics of wave creases and straight creases. To achieve motion equivalence, different lengths of tape spring hinges are used along the package direction, while door hinges are employed at the wave crease. In order to address the motion interference problem during folding and maintain structural stability, constraints are derived, and a discrete nonlinear optimization model is established. The particle swarm optimization algorithm is used and improved to enhance convergence performance and computational efficiency. According to the calculation results, the corresponding folding plates were made, and the folding process and results are consistent with zero-thickness origami. These findings suggest that the proposed thick-panel origami method not only achieves efficient optimization of the geometric design but also preserves the essential characteristics of traditional zero-thickness origami. To aid designers, some key design recommendations based on the parameter analysis are provided for enhancing the deployment ratio.

Zygote structure enables pluripotent shape-transforming deployable structure.

We propose an algorithmic framework of a pluripotent structure evolving from a simple compact structure into diverse complex 3D structures for designing the shape-transformable, reconfigurable, and deployable structures and robots. Our algorithmic approach suggests a way of transforming a compact structure consisting of uniform building blocks into a large, desired 3D shape. Analogous to a fertilized egg cell that can grow into a preprogrammed shape according to coded information, compactly stacked panels named the zygote structure can evolve into arbitrary 3D structures by programming their connection path. Our stacking algorithm obtains this coded sequence by inversely stacking the voxelized surface of the desired structure into a tree. Applying the connection path obtained by the stacking algorithm, the compactly stacked panels named the zygote structure can be deployed into diverse large 3D structures. We conceptually demonstrated our pluripotent evolving structure by energy-releasing commercial spring hinges and thermally actuated shape memory alloy hinges, respectively. We also show that the proposed concept enables the fabrication of large structures in a significantly smaller workspace.

Development of Spring Hinge Models to Simulate Structural Elements of Spherical Graphite Reinforced Concrete

The goals of the study were the formation of a model of concentrated plasticity based on spherical graphite fibers. The goal was to present indicators of the cyclic behavior of structural elements due to the lack of consideration in modern scientific research of the issue of increasing the technical level and reliability of structures due to the addition of innovative materials during the development of structural elements. Taking into account the fundamental shortcomings in construction in the conditions of installing an excess amount of reinforcement, as one of the main mechanisms for achieving strength and reliability. The aim of the study was to develop a method of improving the quality of structural elements using innovative materials through building spring hinge models. The study involved the mathematical simulation, comparison, and system analysis. The result of the work is a developed spring hinge model for simulating reinforced concrete structural elements. The work emphasizes that the obtained experimental model converges to reference data and does not reflect a significant error with the increased number of cycles. It is emphasized that the model degrades with significant calibration, while the numerical strength and hysteresis behaviour matches the experimental data at higher deformation levels. The model of concentrated plasticity based on spherical graphite fibers was developed for the range of indicators of the cyclic behaviour of structural elements. The main characteristics of the reinforced concrete structural elements under consideration in the framework of the study are provided in a table in order to visually separate the groups of structures according to the main parameters. A non-linear model of a spring hinge is graphically shown, which shows the moment of movement of the spring when a monotonous load is applied. An urgent need to build a system of indicators of the structural elements’ cyclic behaviour was emphasized. A concentrated plasticity model based on spherical graphite fibers was built for this purpose. A beam-column was chosen as a reinforced concrete structure, which is based on a zero-length spring pivot hinge at the end of each individual element. This spring pivot hinge is a uniaxial material model with a moment-rotation dependency. Such a dependency is the fundamental basis of the spring hinge model used to simulate reinforced concrete structural elements. The comparison chart of reference and cyclic strength of a spherical graphite reinforced concrete beam is presented graphically. Prospects for further research involve the development of an empirical system of equations depending on the section geometry and the properties of the structure material based on prognostic variables from the list of potential variable characteristics.

A Zigzag-Based Thickness-Accommodating Foldable Prismatic Structure With a Single-Degree-of-Freedom

Abstract Origami inspires various designs of foldable prismatic structures with zero-thickness facets. However, there is a difficulty in directly applying them to thick materials. This paper presents a novel design of the foldable prismatic structure inspired by the zigzag pattern, which can accommodate the thickness of materials easily by placing hinges on the top or bottom surfaces of panels. The foldable prismatic structures are constructed by connecting multiple zigzag strips, in which each strip is made up of uniform-thickness hexagonal panels. By identifying the relationship between the foldable structure and spatial linkages, we analyze the mobility of the assembly based on the matrix method with DH notations. The result reveals that the foldable prismatic structure is equivalent to a network of spherical 4R linkages and Bennett linkages, and its motion has a single-degree-of-freedom. Based on the proposed foldable prismatic structure, a foldable manipulator is developed to demonstrate its potential engineering applications. The actuation strategy is designed by employing a motor-cable-driven system and torsional spring hinges. The physical prototype of the foldable manipulator is fabricated, and experimental results prove that our designs are feasible and effective.

A modified constant-torque spring hinge toward synchronous deployment

Spring hinges, due to their lightweight and energy-saving characteristics, have emerged as an imperative power source for deploying spacecraft appendages. In this paper, a modified constant-torque spring hinge (MCTSH) is proposed for aerospace applications. The conventional constant-torque hinge (CCTSH) is enhanced to bridge the gap toward new applications, resulting in a more compact structure with less friction and wide-range output torques. A novel torque control method is elaborated on for deployable, MCTSH-driven and multi-link mechanisms, thereby simplifying the design procedure via reducing the design variables by half. Given the intricate coupling effects of multi-link mechanisms, a synchronous deployment technique integrating the Newton-Euler dynamics, the design of experiments (DOE) method and the optimization is introduced, and its performance is verified by both simulations and experiments on multi-link grippers. The results demonstrate the high potential of the proposed method for deployable mechanisms toward aerospace applications, e.g., solar array panels and antennas.

Design of Pointing Control Mechanism for Spacecraft Antenna Communication

Satellite antennas are widely used in satellite communications and now have become an indispensable part of satellite. It affects and restricts the performance and functions of the entire wireless communication system. Flexible pointing and low power consumption are required for antennas installed on satellites, which makes the design of the pointing mechanism of the satellite antenna more challenging. This paper focuses on the design and analysis of the pointing control mechanism to help improve the flexibility of satellite communication. An optimized structure consisting of spring hinge mechanism, manipulator arm and universal adjustment mechanism is proposed. The material selection and mechanical analysis are also made. Finally, the pointing angle is described based on the mathematical model of the pointing control mechanism.

Coupling Effect of Nonlinear Stiffness of Tape Spring Hinges and Flexible Deformation of Panels during Orbit Maneuvers

Many solar panels for spacecrafts are deployed by Tape Spring Hinges (TSHs) which have changeable stiffness. The stiffness of TSH is small when panels are folded, and it becomes large quickly in its deployed status. Since the solar panel is a thin sheet, flexible deformation is easily generated by orbit maneuvers. The coupling effect between the nonlinear TSHs and the flexible panels generates obvious vibration which affects the operational stability of the satellite. To investigate this coupling effect, non-deformable, linear deformable and nonlinear deformable panels were modelled by rigid body, modal order reduction method (MORM) and finite element method (FEM), respectively. The driving torque of TSH was described as a function of the rotation angle and angular velocity. The nonlinear properties of the TSH were reflected by one angle-stiffness spline multiplied by one stiffness coefficient. Dynamic responses of a satellite in deployment and orbit steering were analyzed by numerical simulations. Analysis results indicate the local deformation of panels keeps the stiffness of the TSH within a large range which accelerates the orbit maneuvers. However, much vibration is generated by the coupling effect if the luck-up status is broken up. The coupling effect affects the sequence of deployment, overshoot phenomenon and acceleration magnitude of the panels. Although the MORM is more efficient than FEM in computation, we propose FEM is better suited in the design of TSH and in studying the precise control of spacecraft with flexible solar panels and TSHs.

Development of Cyroprotectant Agent-free Cell Cryopreservation by Superflash Freezing of Micro-droplets

Cell cryopreservation is the only way to stop biological activity and is widely used to maintain backups of cells. Conventionally, at least a cryoprotectant agent (CPA) must be added to avoid forming damaging ice crystals and to vitrify water on the inside and outside of the cell. We developed a CPA-free cryopreservation method by superflash freezing based on inkjet cell printing, in that cells were ejected as micro-droplets and deposited on the liquid nitrogen-cooled substrate. The method cryopreserved mouse fibroblast cells at a viability almost as high as the conventional method using dimethyl sulfoxide. To improve the reproducibility and viability further, the thawing process is important as well as the cooling process. Next, we also developed an automatic thawing apparatus that transports the vitrified cells rapidly into a prewarmed medium using a spring hinge. The experimental results indicate that the combination of superflash freezing with the rapid thawing process using the apparatus would become a possible approach to circumvent the problems associated with the addition of CPAs.

Mechanical analysis of folding of a tape spring in a flexible hinge design

This paper is devoted to the study of flexible tape-spring hinges at the stage preceding the numerical optimization of their geometrical parameters. This stage involves the development of a parametric computational model and a method for conducting complex mechanical analysis of the tape spring. The paper presents a detailed description of the parametric model and the methods for numerical simulation of flexible tape spring hinges using an elastoplastic material model. The capabilities of the methods for nonlinear strength analysis of folded tape springs are illustrated by a few examples of their practical implementation. The stability bounds of the tape spring model are determined by the method of finite element modeling, as well as ways to simplify the calculation model. It has been found that in the numerical simulation of folding stresses, the maximum rotation of the free edge of the tape can be restricted to 30°, at which the stress limit is reached. This makes it possible to reduce the time of the numerical experiment by about 3 times. It is shown that the bilinear model of isotropic hardening of the tape material can be replaced by the linear elastic model, since during the parametric optimization the yield strength is set as a criterion. The use of the linear elastic material model makes it possible to distribute computational resources more effectively. The results of this study will be used in further research for developing a parametric optimization scheme that provides an automated search for the most rational designs of flexible tape-spring hinges.

Deployment Dynamics Analysis of an Origami-Folded Spacecraft Structure with Elastic Hinges

Self-actuated deployable space structures present a novel challenge for deployment dynamics modeling efforts, where the system-level influence of strain energy components must be captured. Here, the free deployment of an origami-folded structure through actuation of strain energy hinges is studied. Studies include experimental testing, multibody dynamics modeling, and finite element modeling. An approach for modeling high strain tape spring hinges for use in a multibody simulation of free-deployment dynamics analysis is presented and demonstrated. This approach considers hinges with multiple degrees of freedom beyond the primary fold axis angle. A novel folded deployable structure is designed and prototyped with a segmented fold pattern and strain energy hinges integrated in the design. A suite of deployment tests is conducted on the prototype using videogrammetry. A full simulation of the prototype is constructed from a multibody dynamics model and the hinge model, and the predicted deployment behavior for relative hinge states is evaluated against the experimental testing. Additionally, the prototype deployment is replicated using an explicit dynamic finite element analysis for a performance comparison. The models demonstrate strong correlation for deployment time predictions across the relative hinge states, and the finite element analysis correlates all deployment behaviors.

Experimental and Numerical Investigation of Solar Panels Deployment with Tape Spring Hinges Having Nonlinear Hysteresis with Friction Compensation

In this work, experimental and numerical investigation on the deployment of solar panels with tape spring (TS) hinges showing complex nonlinear hysteresis behavior caused by the snap-through buckling was conducted. Subsequently, it was verified by comparing simulation results by multi-body dynamics (MBD) analysis with test results on ground-based deployment testing considering gravity compensation, termed zero-gravity (Zero-G) device. It has been difficult to predict the folding and unfolding behavior of TS hinges because their moment–rotation relationship showed a nonlinear hysteresis behavior. To realize this attribute, an algorithm that checks the sign of angular velocity of the revolute joints was used to distinguish folding from unfolding. The nonlinear hysteresis was implemented in terms of two path-dependent nonlinear moment–rotation curves with the aid of the expression function (a kind of user subroutine) in MBD software RecurDyn. Finally, it was found that the results of the deployment analysis were in excellent agreement with those of the test when the friction torques of the revolute joints were properly identified by an inverse analysis with the test frames, thus validating the MBD model.

Improved and reproducible cell viability in the superflash freezing method using an automatic thawing apparatus

Cell cryopreservation stops the biological activity of cells by placing them in the frozen state, and can be used to preserve cells without subculturing, which can cause contamination and genetic drift. However, the freezing process used in cryopreservation can injure or damage the cells due to the cytotoxicity of cryoprotecting agents (CPAs). We have previously reported a CPA-free cryopreservation method based on inkjet technology. In this method, the vitrified cells were exposed to the room temperature atmosphere during the transport of the cells using tweezers, which caused devitrification due to the increased temperature and often lowered the cell viability. In the present study, we developed an automatic thawing apparatus that transports the vitrified cells rapidly into a prewarmed medium using a spring hinge. Observations with a high-speed camera revealed that the spring hinge drops the cells into the prewarmed medium within 20 ms. All heat-transfer simulations for the apparatuses with different designs and rotation speeds showed that the cells remained below the glass-transition temperature during the transport. Finally, the apparatus was evaluated using mouse fibroblast 3T3 cells. The cell viability was improved and its reproducibility was enhanced using this apparatus. The results indicate that the combination of superflash freezing with the rapid thawing process represents a promising approach to circumvent the problems typically associated with the addition of CPAs.

Flexural tensegrity of segmental beams

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.

Design, Simulation and Failure Influence of Tape Spring Hinges in a Large Deployable Antenna

The design, simulation and failure influence of tape spring hinges in a large deployable antenna is studied. By sensitivity analysis between modal frequencies of the large deployable antenna and stiffness coefficients of the tape spring hinge, it is found that compression stiffness along longitudinal axis and bending stiffness about transverse axis are the key points of tape spring design. Stiffness coefficients, buckling loads and bending moments of the tape spring hinge are obtained by mechanical simulation. By in orbit disturbance analysis, disturbance loads applied on the tape spring hinge result from satellite attitude control and scanning mechanism operation are presented. Finally, failure influences of the tape spring hinges on both antenna modal frequencies and pointing accuracy are studied.

큐브위성 임무를 위한 테이프 스프링 힌지의 비선형 거동 분석 및 실험

큐브위성 임무를 위한 테이프 스프링 힌지의 비선형 거동 분석 및 실험

Parameters optimization design of tape spring considering fatigue performance

As a crucial part of micro-satellite, the spatial deployable mechanism has the direct effects on satellite performance and success or failure of flight mission. With requirements of lightless and low cost for satellite, the tape spring hinges are widely used for their simple structural form, high reliability of deployment, high-driving performance and accurate positioning in deployable mechanism. Strain energy stored in the folding process of tape spring hinge is transformed into kinetic energy to achieve the deployment of solar panels. When in full deployment, the tape spring hinge can realize self-locking based on its critical moment. Tape spring is the crucial component of a novel space deployable structure that applied to solar panels. Its full deployment determines the normal function of satellite in space. Mechanical properties, steady-state moment and fatigue life, are observed in folding and deploying processes, which are affected by geometric parameters. Influences of thickness, subtended angle, radius and length on the fatigue life of tape spring are carried out to through numerical simulations so as to ensure a multi folding and deploying cycles for tape spring hinge. Results show that thickness has the greatest influence on the fatigue life, subtended angle and radius are second, and the influence of length on fatigue life is relatively small. On the basis, the optimal model is established based on response surface methodology with the thickness and radius as design variables, steady moment as constraint, and fatigue life as optimization objective. By using genetic algorithm to solve the model, optimal design is obtained within the constraint, and then the optimal design is remodeled and simulated, and the obtained results indicate the accuracy of the optimal design. This research could be a reference for the stability design of space deployable structures.

Quasi-static analysis and multi-objective optimization for tape spring hinge

Mechanical attributes of interest are always mutually exclusive in the design process of tape spring hinge. Here we present a complete optimization framework consisting of computational mechanics, optimization design, engineering application, and experimental research to compromise mechanical attributes such that an optimal solution set can be obtained to provide design strategies for engineering practices. Tape spring hinge in folding and unfolding processes with large non-linearity is firstly simulated using quasi-static analysis technique. During the quasi-static process, the ratio of kinetic energy to strain energy is observed to determine mass scaling parameters that measure the precision of analysis. Based on the parameters analyzed, moment-rotation responses of tape spring hinge in quasi-static folding and unfolding processes are investigated and experimentally verified. Yield theory derived from the combination of thin shell theory and Tresca yield criterion is introduced to control the yield of the hinge during folding and deploying processes. In addition, tape spring hinge is released transiently when in spatial conditions; thus the fundamental frequency is calculated and selected herein to be a measurement of stiffness that is maximized to avoid the vibration. Then a multi-objective optimization model is established using the derived yield theory control equation and critical moment as optimization constraints, with the fundamental frequency and strain energy as objectives. The non-dominated sorting genetic algorithm is used to solve the optimization model, and then feasible solution distribution and Pareto frontier are obtained. These results are compared and discussed with two additional single-objective optimizations. Ultimately we achieve the optimal design for tape spring hinge, which is verified well with numerical simulation.