Gossamer Space Structures Research Articles

Self-rigidizable Kapton-SMA conical booms: A comprehensive numerical and experimental study

Inflatable gossamer space structures require structural rigidity after partial or complete out-gassing of the inflation gases. The current study focuses on the rigidity generation in a fully deployed, out-gassed Kapton laminated conical boom. A novel approach is applied to produce out-of-plane structural stiffness in the gossamer structure using the shape memory alloy (SMA) wires embedded between Kapton laminate membranes. The finite element analysis is performed to find the generated stiffness in the system and validated with the experimental results. To this end, an experimental set-up is developed to provide a stable and uniform thermal environment with the inflation facility. Additionally, different measuring devices are also employed in the test set-up to note the readings of pressure, temperature, and displacement sensors. Moreover, the Kapton and SMA material properties are found experimentally, and their material models are validated with published studies. Furthermore, constitutive equations of the SMA-Kapton composite are also included in the study. After that, a parametric study is done to know the effect of design and material parameters on the boom's stiffness.

A review on developments of deployable membrane-based reflector antennas

The gossamer space structures are very large and ultra-lightweight structures. A large aperture-based space structure is highly efficient in capturing signals from a wide coverage area. However, their deployment in space has been a critical challenge to date. Extensive research has been carried out on various types of gossamer structures used for earth exploration and deep space applications. Space antenna, in general, should have a large electrical aperture, be light in weight with small stowage volume, be easily deployable in space, and thermally stable. The antenna consists mainly of a reflector as a major part and a torus for supporting the reflector, electronic control unit, and struts. This paper covers an extensive review of gossamer space structure considering different categories of large deployable antennas. More attention has been given to a large membrane-based antenna having a parabolic reflector. This work includes the study of designs, analyses, and development of prototypes and successful deployment of space structures in orbit. We emphasize understanding the behaviour of thin membrane, their static and dynamic characteristics, wrinkling control, shape control of thin membrane reflector, and recent advances in deployment techniques of large deployable antenna structures.

Deployment behavior of planar gossamer space structures made of plain-woven textile

Multifunctional membrane space structures have been developed in the past to realize solar arrays, array antennas, and other applications. However, the deployment of a folded membrane often requires fluctuating forces with high peaks, caused by the stiffness of the crease lines. This study proposes the use of a plain-woven textile as the base membrane for the planar deployment structures primarily because of its high packaging efficiency. The deployment forces required for the folded plain-woven textile structures to be employed in future space applications are experimentally measured. The deployment forces are compared between the proposed textile structures and the conventional film-based membranes to characterize the deployment behavior of the textile structures. Two types of experiments are conducted in this study for the one-dimensional deployment of v-folded membranes and the two-dimensional deployment of quarter Flasher origami structures, respectively. The advantages presented by the deployable textiles are as follows: (i) they require smaller and smoother deployment forces, and (ii) they are insensitive to imperfect boundary conditions. These features are important for the reliable deployment of future space structures.

Nonlinear vibration control effects of membrane structures with in-plane PVDF actuators: A parametric study

In recent years, with the increasing use of membrane structures in space applications, the problems of large-amplitude (compared to the thickness) vibrations arise; leading to the degradation of their working performance. It is challenging to control the large-amplitude vibrations of membranes due to the high flexibility, low damping, and strong geometrical nonlinearity. In this study, polyvinylidene fluoride (PVDF) actuators are considered to develop the active vibration control of a pre-tensioned Kapton membrane. The governing equations are established based on the geometrically nonlinear theory of plates, taking into account the modal control force induced by the actuators. To analyze the nonlinear dynamic characteristics of the membrane, the theoretical and approximate solutions of nonlinear frequencies of the membrane are obtained, and the discrepancies between the two solutions under different vibration amplitudes are discussed. Control performance for both free vibration and harmonic forced vibration of the membrane is numerically studied. A comprehensive parametric study is carried out to investigate the influences of different system parameters, including the pretension and the size of the membrane, and the position and number of the actuators, on the control performance. Analytical results indicate that the vibration of the membrane can be effectively suppressed with the appropriately laminated PVDF actuators. The results of this research can be extended to the active control of different gossamer space structures.

Rigidisation of deployable space polymer membranes by heat-activated self-folding

Current gossamer space structures such as solar sails usually rely on bracing structures, inflation gas, or centrifugal force to deploy and maintain a structural shape, which leads to a system that is sometimes complicated, while a concise system can be achieved if the gossamer structure could self-rigidise and support load. The present study proposes a self-folding polymer membrane based on space-qualified materials and is potentially mass-producible by industrial roll-to-roll processes. It can permanently transform a flat gossamer membrane into a load-bearing 3D configuration when heated by sunlight in space, while the folding-induced shape bifurcation and buckling are prevented using a kirigami hinge design. The shape transformation is demonstrated in lab by a tubular and an origami structure that are formed from a flat membrane when heated to 82 °C in oven. Thermal radiation analyses have also verified the feasibility of sunlight-activated folding in space when vapour-deposited metallic coatings are applied onto the hinges. The proposed material offers a new generation of gossamer space membrane that can automatically morph from a stowed configuration to a load-bearing structure, and potentially provide built-in functionalities.

Experimental verification on simplified estimation method for envelope curve of wrinkled membrane surface distortions

The effectiveness of a simplified method for estimating an envelope curve of wrinkled-membrane-surface distortion, which was recently proposed by the author, was experimentally assessed. The equation is formulated using three physical quantities regarding wrinkles: the length of the wrinkle line, the major principal strain in wrinkled regions, and the in-plane shrinkage strain appearing in the orthogonal direction of the wrinkle line. Since these three physical quantities are attributed to two-dimensional problems, the formula makes it possible to simply estimate wrinkle amplitude without a cumbersome bifurcation analysis. Applying a wrinkle strain in tension-field theory instead of the in-plane shrinkage strain in the formula, a simplified method to estimate an envelope curve of a wrinkled membrane with a low computational cost was developed using the wrinkling analysis with tension-field theory. Wrinkling phenomena appearing on two membrane models subjected to an in-plane shear and a corner-tension load were experimentally measured by photogrammetry using the direct linear-transformation method and a laser-displacement sensor. The experiment model was then subjected to a finite element analysis using tension-field theory, and an envelope curve of the wrinkled membrane was estimated using the method. The estimated envelope curves appropriately captured the actual wrinkle amplitude appearing on the membrane surface regardless of the formation process of wrinkles. From the result, the validity of the proposed estimation method was confirmed. This paper offers an effective method to predict the magnitude of the wrinkled-membrane-surface distortion with a low computational cost, and will assist the development of future gossamer space structures incorporating membranes.

Decentralized adaptive fuzzy vibration control of smart gossamer space structure

Gossamer space structures technology have gained widely applications in space missions. However, the vibration problem is a great challenge which makes the technology complicated. The overall motivation of this work is to develop a vibration control system for gossamer space structures. In this study, a space membrane structure with piezoelectric stack actuators bracketed on its support frame is considered. First, the description of the smart space membrane structure and its dynamic model are presented. Then, a decentralized adaptive fuzzy control method is developed to control the structure vibration. Finally, experimental system is built up, and two vibration control experiment cases are carried out to verify the proposed control method. Experimental results demonstrate that the proposed control method is more effective than the fuzzy control method.

Shape memory polymer composites with woven fabric reinforcement for self-deployable booms

To characterize the nonlinear relationship between load and displacement and its dependency on temperature and time variations, the rate form of thermomechanical constitutive equations for shape memory polymers is newly derived. Experimental tests of the shape memory polymers are analyzed to acquire the parameters needed for the model. In order to generate a fast recovery rate and a higher recovery ratio, an asymmetric shape memory polymer composite reinforced with woven fabrics is developed and fabricated. Moreover, the efficiency of the asymmetric shape memory polymer composite is evaluated through shape recovery tests after bending. A numerical model of the shape memory polymer composite is newly established. In addition, the structural nonlinear behavior of the asymmetric shape memory polymer composite is analyzed with time and temperature dependence. A “[Formula: see text]”-shaped cross-sectional shape memory polymer composite boom is fabricated, and its deployment procedures are demonstrated for the application of self-deployable booms in gossamer space structures.

Folding patterns of planar gossamer space structures consisting of membranes and booms

The combination of large membranes and light-weight deployable booms, often called a gossamer structure, has enabled innovative space missions, such as solar sailing, to become possible. Though many designs have been proposed and demonstrated, two problems remain regarding the folding patterns of the membranes. The first problem involves considering the thickness of a membrane to enable uniform and compact folding. The other involves membrane-folding patterns that allow for connecting the membrane to the booms at multiple points and deploying them together while minimizing the use of complex mechanisms. This study proposes three methods that consider the thickness, and two of them can keep the crease lines straight, in contrast to the conventional non-straight crease line solutions. In addition, this study derives one effective design to integrate a membrane with diagonal booms through the systematic classification of existing membrane folding patterns.

Electrostatically inflated gossamer space structure voltage requirements due to orbital perturbations

This paper explores the concept of using electrostatic forces for deployment of gossamer space structures. The Electrostatically Inflated Membrane Structure (EIMS) uses two conducting membranes that are interconnected through membrane ribs. An absolute electrostatic charge is applied to the structure through active charge emission. This causes repulsion between layers of lightweight membranes that inflates the EIMS system and tensions the membranes. Assuming positive tensions, the EIMS system is modeled as a rigid system. Typical orbital perturbations are considered such as solar radiation pressure, differential gravity, and atmospheric drag which may compress the structure leading to shape destabilization. Restricting the analysis in this paper to flat membranes, the minimum potentials required to exactly compensate for the worst case scenario of differential solar radiation pressure at geostationary altitudes are estimated to be on the order of hundreds of volts. In low Earth orbit, voltage magnitudes of several kilovolts are required to reach an inflation pressure to offset the normal compressive drag pressure.

A new computational method for wrinkling analysis of gossamer space structures

A new Modified Displacement Component (MDC) method is proposed to accurately predict wrinkling characteristics in the membrane by eliminating the singularity of the displacement solution. In MDC method, a singular displacement component is primarily obtained at the wrinkling point by introducing the first-order characteristic vector multiplied by a positive intermediate parameter in the singular stiffness matrix. The non-singularity displacement solution is then obtained by modifying the singular displacement component based on three equality relationships at the wrinkling point. Where, the accurate introduction and the timely removal of the critical wrinkling mode are two key steps. In our simulation, we use a direct perturbed method to accurately consider these two key steps. In the direct perturbed method, some small, quantitative, out-of-plane forces are applied onto the membrane surface directly based on the first wrinkling mode, and then removed immediately after wrinkling starts. Several effective strategies are then used to advance the convergence. A wrinkling test using photogrammetry is used to verify the validity of our method. In addition, we also studied the secondary wrinkling characteristics occurred in the post-wrinkling phase in the end. The secondary wrinkling characteristics are the basic explanations of the wrinkling expansion and evolution in the post-wrinkling phase.

VIBRATION CHARACTERISTICS SIMULATION OF WRINKLED CIRCULAR ANNULUS-SHAPED GOSSAMER SPACE STRUCTURE

Ultra-lightweight Gossamer space structures have received the wide attention due to their small packaging volume and low launching cost. Since wrinkles are a common deformation state and the main failure mode of such structures and vibration behaviors are the major factor of the structural design and control, a better understanding of the wrinkling characteristics and the vibration behaviors of the wrinkled membrane structure is thus very essential and desirable. In this paper, a modal analysis method incorporating the wrinkling analysis is presented to simulate the vibration characteristics of a wrinkled membrane structure. The effects of the wrinkles on the structural vibration behaviors are also summarized in detail in the end.

An Experimental Study on Wrinkling Behaviours and Characteristics of Gossamer Space Structures

Abstract: Ultra-large and ultra-lightweight gossamer space structures have received wide attention because of their small packaging volume and low cost. Wrinkle is the common deformation outcome and the main failure mode of such structures. The experimental test is essential for the wrinkling analysis, as contact test cannot be used to accurately determine wrinkling behaviour because of lightweight and flexibility. A novel non-contact dot-printing photogrammetry (DPP) based on the technology of the printed-dot targets is presented to measure wrinkling characteristics. The characteristics of wrinkle development of gossamer space structures are obtained by incorporating the DPP method and a tension wrinkling (TW) test. Results reveal that wrinkle formation is the predominant form of bifurcation when the membrane is undergoing in-plane displacement. Over-contraction deformation is the special characteristic of the wrinkles, which reflects the degree of wrinkling and region in the wrinkled membrane. The development of wrinkling can be divided into five characteristic phases, and the occurrence of the wrinkles is followed by an abrupt jump variation. DPP measurement and TW test are the effective ways to obtain accurately the wrinkling behaviours and characteristics in small-scale gossamer structures. Finite element results based on nonlinear post-wrinkling analysis are used to validate the experimental test. The numerical predictions agree well with the experimental results.

An Experimental Study on Wrinkling Behaviours and Characteristics of Gossamer Space Structures

Abstract: Ultra‐large and ultra‐lightweight gossamer space structures have received wide attention because of their small packaging volume and low cost. Wrinkle is the common deformation outcome and the main failure mode of such structures. The experimental test is essential for the wrinkling analysis, as contact test cannot be used to accurately determine wrinkling behaviour because of lightweight and flexibility. A novel non‐contact dot‐printing photogrammetry (DPP) based on the technology of the printed‐dot targets is presented to measure wrinkling characteristics. The characteristics of wrinkle development of gossamer space structures are obtained by incorporating the DPP method and a tension wrinkling (TW) test. Results reveal that wrinkle formation is the predominant form of bifurcation when the membrane is undergoing in‐plane displacement. Over‐contraction deformation is the special characteristic of the wrinkles, which reflects the degree of wrinkling and region in the wrinkled membrane. The development of wrinkling can be divided into five characteristic phases, and the occurrence of the wrinkles is followed by an abrupt jump variation. DPP measurement and TW test are the effective ways to obtain accurately the wrinkling behaviours and characteristics in small‐scale gossamer structures. Finite element results based on nonlinear post‐wrinkling analysis are used to validate the experimental test. The numerical predictions agree well with the experimental results.

Damage Tolerance in Naturally Compliant Structures

In this study, the damage tolerant design in a particular compliant structure, the spider web, has been studied. The orb web spider has evolved over the last 180 million years. This long period of evolution has made the present spider web, an elegant, natural, lightweight structure that efficiently resists different loads, such as wind and insect impact. It can function as a net for catching prey even if several elements are broken. Nature has accomplished these tasks by optimizing its form of construction, and by making spider silk a biopolymer with superior elasticity and tensile strength. Spider webs are clearly one of the most efficient structures engineered by nature. In this study, we attempt to understand how the spider web achieves its damage tolerance. A finite element (FE) model of an ideal spider web has been created using the FEMAP pre- and post-processing software and analyzed using the ABAQUS nonlinear FE code. Both the static and dynamic problems have been considered, and experimental validation has also been performed. How stress is redistributed in the face of damage and how the loss of web elements affects the dynamic response of the web have been considered. Finally, the numerical simulations have been compared to physical experiments. Instead of actual spider webs, artificial nets have been examined; the first natural frequencies for different damage configurations have been measured by laser vibrometer. A FE model of the net has also been created in FEMAP and analyzed by ABAQUS. In both analyses, the same elements have been removed systematically from the center of the web and the first natural frequencies have been determined. The prediction matches well with the experiment. The results of this study may give insight into other ultra-lightweight structures, such as cable-stayed bridges and gossamer space structures.

Pattern evaluation for in-plane displacement measurement of thin films

Ultra-lightweight spacecraft incorporating “gossamer” structures are extremely compliant, which complicates control, design, and ground testing in full scale. One approach to model the behavior of a full-scale gossamer structure is to construct a small-scale model test article that can be used to verify a corresponding small-scale computer model. Once the predictions of the computer model have been verified by measurement of the physical test article, it can be scaled up to allow computation of the full-scale structure behavior. As model verification requires accurate deflection measurements at multiple points along the surface of the structure, a sensing system that provides full-field data without changing the dynamic response of the structure must be developed. Hence, an optical approach is taken. Since the thin films used in gossamer space structures are typically smooth and featureless, targets must be incorporated into the film surface to enable tracking of both in-plane and out-of-plane displacements. A krypton fluoride excimer laser system was used to etch 35 μm wide linear features approximately 0.1 μm into the surface metallization of both 50.8 μm polyester and 127 μm polyimide films. These optically diffuse surface features, designed mainly to investigate the precision of the laser etching method, were used as targets for ultra-close-range photogrammetry, the method chosen for displacement tracking. A force applied to the surface of the etched mirror (test article) produced in-plane and out-of-plane deformations that were resolved via ultra-close-range photogrammetry. To measure the in-plane tracking resolution, 1.5 and 3.0 mm circular dots were added (using ink) to the surface of the thin film, and some of these targets were tracked as the test article was translated on a precision linear stage. In-plane tracking resolution using ultra-close-range photogrammetry was related to the ground sample distance of the camera, which in this case was 51.25 μm pixel−1 (equal to the ratio of sample dimension to number of pixels in the field of view). Using a manual technique to identify features of the etched pattern for tracking, the mean tracking error was about 13 μm (σ=43 μm). Using an automated, subpixel marking technique to identify the 1.5 mm circular targets, the mean tracking error was 22 μm (σ=13 μm). Neither of these methods achieved the desired 10 μm tracking resolution.

Pattern Evaluation for In-plane Displacement Measurement of Thin Films

Ultra-lightweight spacecraft incorporating “gossamer” structures are extremely compliant, which complicates control, design, and ground testing in full scale. One approach to model the behavior of a full-scale gossamer structure is to construct a small-scale model test article that can be used to verify a corresponding small-scale computer model. Once the predictions of the computer model have been verified by measurement of the physical test article, it can be scaled up to allow computation of the full-scale structure behavior. As model verification requires accurate deflection measurements at multiple points along the surface of the structure, a sensing system that provides full-field data without changing the dynamic response of the structure must be developed. Hence, an optical approach is taken. Since the thin films used in gossamer space structures are typically smooth and featureless, targets must be incorporated into the film surface to enable tracking of both in-plane and out-of-plane displacements. A krypton fluoride excimer laser system was used to etch 35 μm wide linear features approximately 0.1 μm into the surface metallization of both 50.8 μm polyester and 127 μm polyimide films. These optically diffuse surface features, designed mainly to investigate the precision of the laser etching method, were used as targets for ultra-close-range photogrammetry, the method chosen for displacement tracking. A force applied to the surface of the etched mirror (test article) produced in-plane and out-of-plane deformations that were resolved via ultra-close-range photogrammetry. To measure the in-plane tracking resolution, 1.5 and 3.0 mm circular dots were added (using ink) to the surface of the thin film, and some of these targets were tracked as the test article was translated on a precision linear stage. In-plane tracking resolution using ultra-close-range photogrammetry was related to the ground sample distance of the camera, which in this case was 51.25 μm pixel−1 (equal to the ratio of sample dimension to number of pixels in the field of view). Using a manual technique to identify features of the etched pattern for tracking, the mean tracking error was about 13 μm (σ=43 μm). Using an automated, subpixel marking technique to identify the 1.5 mm circular targets, the mean tracking error was 22 μm (σ=13 μm). Neither of these methods achieved the desired 10 μm tracking resolution.

Dot-Projection Photogrammetry and Videogrammetry of Gossamer Space Structures

This paper documents the technique of using hundreds or thousands of projected dots of light as targets for photogrammetry and videogrammetry of gossamer space structures. Photogrammetry calculates the three-dimensional coordinates of each target on the structure, and videogrammetry tracks the coordinates versus time. Gossamer structures characteristically contain large areas of delicate, thin-film membranes. Examples include solar sails, large antennas, inflatable solar arrays, solar power concentrators and transmitters, sun shields, and planetary balloons and habitats. Using projected-dot targets avoids the unwanted mass, stiffness, and installation costs of traditional retroreflective adhesive targets. Four laboratory applications are covered that demonstrate the practical effectiveness of white-light dot projection for both static-shape and dynamic measurement of reflective and diffuse surfaces, respectively. Comparisons are made between dot-projection videogrammetry and traditional laser vibrometry for membrane vibration measurements. The paper closes by introducing a promising extension of existing techniques using a novel laser-induced fluorescence approach.

Modeling of Gossamer Space Structures with Distributed Transfer Function Method

A new structural modeling and analysis method, the distributed transfer function method, is presented for application to gossamer space structures. The distributed transfer function method uses distributed transfer functions, instead of shape function used by traditional finite element solvers, to represent the displacement field. The distributed transfer function method maintains the modeling flexibility of the finite element method, so that it is capable of modeling multibody complex structures, but it requires much fewer nodes and results in a significant reduction of computational time. The distributed transfer functions give rise to closed-form analytical solutions of both displacement and strain fields. As a result, the distributed transfer function method only decomposes a structure at those points where multiple components are connected, to keep each component as large as possible. Gossamer space structures are generally composed of several long booms and large membranes. Therefore, the distributed transfer function method can be used to model a gossamer structure with a small number of unknowns and matrices of low order. It offers very accurate results with high computational efficiency. The distributed transfer function method is applied to investigate the sensitivity of buckling strength of an inflatable/rigidizable boom to the variations in bending stiffness.