大形宇宙構造物用の磁気支持スライダ展開試験装置

A technique is introduced for the kinematic synthesis of deployable cable-stiffened truss structures. This technique, which is an extension of a prior procedure [l-21 for generating deployable truss structures, can be applied to generate all concepts of cable-stiffened truss structures as well as all their deployable derivatives. Examples illustrating the implementation of this new technique, along with a discussion of the results achieved. are included in this article. The primary function of a deployable structure is to maintain a stable configuration in its deployed state. This is reflected in current design practices of trading off decreased deployment or retraction performance for increased structural performance. As a result, various designs of deployable truss structures (with, and without cables) have been introduced that are over-constrained during deployment/retraction, i.e. deployment/retraction of these structures can only be achieved through the deformation of individual links or by exploiting symmetric features of the structure. The number of different conceptual designs of deployable structures that are based on a given structural configuration is unlimited, if deployable structures are permitted to be overconstrained during deploymenthetraction. For this reason, researchers in the area of deployable structures have given little attention to the systematic design of deployable truss structures and have instead devoted much of their attention to the introduction and discussion of novel concepts of deployable truss structures [3-171. If, on the other hand, it is assumed that the primary function of a deployable structure is to serve as a mechanism with a minimum number (i.e. at least one) of degrees-of-freedom, then the number of different conceptual designs that are based on a given structural configuration is finite. Hence, it is then possible to generate all possible designs for a given structural configuration. The assumption that a deployable structure is not constrained during deployment/retraction has enabled the development of a technique for the generation of all conceptual designs of deployable truss structures that can be used as building blocks (modules) of much larger structures [I-21. It should be noted that this technique, referred to as kinematic synthesis of * Sr. Mechanical Engineer, Member AIAA deployable structures, does not assume that the structural configuration is known but instead uses the characteristics of a given class of structures (i.e. truss modules) to generate all possible configurations of structures in this class. The limitation of this technique to truss modules has been avoided in the Explosion-Implosion technique [19], developed by the same authors, for the generation of allconceptual designs of deployable truss structures of which the locations of the nodes are known. Both techniques have been shown to result in the generation of an enormous, yet finite, number of novel conceptual designs as well as those that have been reported in the literature. Furthermore, by limiting the degrees-of-freedom available at individual joints, conceptual designs can be generated of deployable structures that are overconstrained during deployment/retraction. Although the kinematic synthesis technique and the explosionimplosion technique result in the generation of an enormous number of conceptual designs of deployable truss structures, they are not applicable to truss structures with cables. Yet, cable-stiffened truss structures have important advantages such as the reduction in mass and/or reduction in joints that can be achieved by replacing links in truss structures with cables. The objective of this article is to modify the technique introduced in [I-21 such that the new technique is also applicable to cablestiffened truss structures. This new approach can then be applied to generate novel concepts of deployablecable-stiffened truss structures as well as those that have been reported in the literature.

There has been increasing demand for larger space structures to satisfy the requirements of astrophysics missions. However, storage space for payloads in satellites is limited, so deployable structures are used in most space missions to minimize storage space and consequently, to reduce launch costs. This work proposes a deployable truss structure which can improve the packaging efficiency of the existing truss structure. The main feature of the proposed structure is that it can be stored in a flat form. Each unit consists of Scissor-like Elements (SLEs) and the whole structure is deployed in a three-dimensional form with a simple mechanism. The detailed configurations and mechanism of the proposed structure are discussed. The geometric constraints for folding the proposed structure into a planar form were analyzed. A kinematic analysis to describe the motion of the structure was also performed. Then the packaging efficiency with respect to length, which is an important performance index of such deployable structures, was analyzed and compared with a typical truss structure.

Scissor-like element has a number of applications in deployable structures such as planar deployable structure (PDS) and ring deployable structure(RDS). However, the mobility analysis of the multi-loop deployable structures is made more difficulty by the traditional mobility formula, because the deployable structure is a very complex structure with multi-loop. Therefore, On the basis of screw theory, the calculation method of mobility of deployable structures of SLE is thoroughly discussed. In order to investigate the mobility, decomposing and composing structures(DCS) are developed, and the basic units are able to be obtained. On the basis of the deployable structures’ geometrical characteristics, there exists a closed-loop quadrilateral structure and some non-closed-loop quadrilateral structures in PDS. Also, a six legs parallel structure is present in RDS. The basic units’ mobility can be solved by both the methods of screw theory and topology constraint graphs. Then, composing the related basic units, the formula of planar deployable structures’ mobility can be built and solves the mobility of ring deployable structure. The analysis method solves the mobility analysis of the multi-loop deployable structures which is difficulty by the traditional method, and plays an important role in further research about the mobility of other complex deployable structures.

A review of large space structures activities from 1973 to 1979 is presented. Long-range studies of space colonies, gigantic solar power stations and projected earth applications revived interest in space activities. Studies suggest opportunities for advanced antenna and platform applications. Matching low-thrust propulsion to large flexible vehicles will be a key technology. Current structures technology investigations include deployable and erectable structures and assembly techniques. Based on orbited structures experience, deployment reliability is a critical issue for deployable structures. For erectable structures, concepts for earth-fabricated and space-fabricated memb

The truck-mounted solar collector testing system is a flexible and convenient testing device. However design of thus a system is much more difficult than that of the fixed solar collector testing system, because it needs consideration in every respect so as to make sure the following: accurate testing, accommodation of the reduced volume of the testing system, stability of the testing system, addition of a removable device and so on. This article explores the systematic design of the truck-mounted solar collector testing system, points out the design issues to be considered, propose an appropriate design plan, and finally conducts the main force calculation. Solar energy is one of the cleanest sources; it is green and pollution-free. Today, environmental pollution is getting worse and worse; thus application of solar energy is becoming more extensive. A solar collector is defined as any of various devices that absorb the solar radiation and deliver the heat energy to the medium of heat transfer device. Solar collectors are not a direct consumer-oriented product, but key components that form various solar thermal systems, such as solar water heaters, solar energy dryers, solar industrial heaters and so on, of which the solar collectors are a core part of the system. At present solar heat pipe collectors and collector plates are the two most widely used products of solar collectors. Factory productions of such products are subject to inspection before they can be put on the market. Currently product testing of this kind is performed collectively in fixed locations; consequently, it is vulnerable to the geographical conditions, climate changes, and other factors in the location. A truck-mounted solar collector testing system is a system that integrates both testing systems, heat pipe collectors and collector plates, in a vehicle, which can be driven into the manufacturers that produce heat pipes and/or heat plates or other places where testing conditions can be met according to the requirements. By doing so, the problems associated with the fixed testing system can be solved. However, design of truck-mounted type solar collector testing system is much more difficult than that of fixed solar collector testing system. In addition to testing accuracy, it must also take the reduced volume of the testing system into account to ensure that the system can be accommodated into a smaller space of the vehicle. Furthermore, the stability of the testing system must be assured. Finally a removable device needs to be added to the system for convenience. In the following, we show our design of the truck-mounted solar collector testing system and calculations for the related stress analysis.

In this study, a passive truss-link mechanism applicable to large-scale deployable structures was designed to achieve successful deployment in space. First, we simplified the selected truss-link mechanisms to the two-dimensional geometry and calculated the degrees of freedom (DOF) to determine whether a kinematic over-constraint occurs. The dimensions of the truss-link structure were determined through a deployment kinematic analysis. Second, a deployment simulation with the truss-link was conducted using multibody dynamics (MBD) software. Finally, a deployment test was performed considering gravity compensation, and the results were compared with those of MBD simulation. The results of the deployment simulations were confirmed to be slightly faster than those of the deployment test due to friction effects existing in the joints and gravity compensation devices. To address this issue, inverse identification of the equivalent frictional torque (EFT) at the revolute joints in the deployment test was conducted through response surface methods (RSM) combined with the central composite design technique. As a result, we confirmed that the deployment angle history of the deployment simulation was similar to that of the deployment test.

Structural design and optimization of large cable–rib tension deployable antenna structure with dynamic constraint

Controlled shape-morphing metallic components for deployable structures

[Abstract] In the past decades, Synthetic Aperture Radar (SAR) antennas have attracted much attention for its advantages over other optical based antennas in earth observation because of their all-weather and daylight independent capabilities. The large size membrane SAR antennas has the advantages of achieving large gain and good resolution with ultra light mass. In this paper, we have developed a foldable deployable structure to deploy a membrane antenna in two directions, longitudinal and lateral directions. The longitudinal deployment is driven by two symmetrically arranged deployable structures. Each of them has a six-bar linkage mechanism and two closed-cable-loops. Several motion controllable hinges fulfill the lateral deployment. The hinge is composed of a SMA actuator, tape springs and a motion control mechanism. In this paper, the six-bar linkage has been designed with an optimal method to meet the demand of simultaneous deployment of all frames and keeping in a common plane after they are fully deployed. To analyze the dynamic performance of the driving mechanism, the multibody dynamic analysis software ADAMS has been used. For large size antennas, the effect of the frame flexibility on the dynamic performance of the system cannot be ignored. Using ADAMS/Flex, we studied the effect of frame flexibility on the dynamic properties of the support structure. Also, the natural frequencies and mode shapes of the deployed structure have been analyzed using finite element method. In this paper, the structure of the motion controllable hinge is introduced and the relationship between the joint output torque with respect to its parameters is studied.

This research deals with materials for deployable large space structures such as large space antennas and tube-type structure support members. Motors are often used as actuators for deployable structures, but the use of functional materials such as shape memory alloys and shape memory polymers used in the field of adaptive structures is also an effective ways from the viewpoint of weight reduction. In this report, we focus on shape memory polymer, and propose a composite material called CF-CNT-SMP by adding thermal conductivity by CNT to the conventional CF-SMP, which is a composite material with carbon fiber that is in charge of high tension. Then the efficiencies of this CF-CNT-SMP are reported by acquiring material properties and shape recovery performance.

The design and performance of an IR FPA test system are described. The parameters, techniques, and equipment required for an IR test system are discussed. An analysis of focal planes is presented to extract the last dB of performance, emphasizing the minimization of required device testing time. The CECOM test system is presented, including the instrument controller, the five source types for characterizing IR FPAs, the electronics, and the protective plexiglass enclosure. Critical test parameters and bias and clocking supply specifications are set forth. Printers which display the results are described, and a buffer/spooler is suggested to increase output rate. Data presentation is discussed. Tests on FPAs and readouts, such as dc uniformity, rms noise, 1/f noise, detectivity, linearity, and responsivity, can be conducted in an automated mode. The possibility of automated testing of optical crosstalk, spectral response, and optical area is mentioned. Future improvements to the facility are listed. Improved yields and increased FPA testing throughput in IRFPA production programs can result from the IRFPA test system facilities.

We describe the development of an engineering model of the DOLCE payload which will demonstrate on orbit for the first time the deployment of an ultralight Caltech SSPP structure. Deployment tests at the subsystem and system levels, launch load analysis and testing, and accelerated aging tests have been conducted. The DOLCE payload will be launched with the SSPD-1 mission which will demonstrate space-based solar power key enabling technologies in photovoltaics, power beaming, and deployable structures.

Large steel space structures, when exposed to a harsh corrosive environment, are inevitably subjected to atmospheric corrosion and stress corrosion cracking. This paper proposes a framework for assessing the corrosion damage of large steel space structures subjected to both stress corrosion cracking and atmospheric corrosion. The empirical model for estimating atmospheric corrosion based on measured information is briefly introduced. The proposed framework is applied to a real large steel space structure built in the southern coastal area in China to assess its corrosion damage and investigate the effects of atmospheric corrosion on stress corrosion cracking. Based on the results, the conceptual design of the corrosion monitoring system of large steel space structures is finally conducted as the first step for a real corrosion monitoring system.

Comparative finite element and experimental analysis of a quasi-static inflation of a thin deployable membrane space structure

Shape memory polymer composite (SMPC) structures, due to their ability to be formed into a small compact volume and then transform back to their original shape, are considered as a solution in the design of light-weight large deployable space structures. There is a wide array of constitutive and qualitative work being done on SMPC’s but little or no development of dynamic equations. This paper documents a macroscopic model for the shape fixation and shape recovery processes of a SMPC cantilever beam. In particular the focus is on the shape fixation process, whereby a quasi-static equilibrium model can be used instead of a full equation of motion. Numerical results are obtained in this regard by use of finite difference approximation with Newton’s method. This formulation combines a nonlinear geometric model with a temperature dependent constitutive law. Additionally, the dynamic equations of the SMPC cantilever are derived. Future work will include a dynamic numerical model, and a finite element model of the SMPC structure.