Deployable Truss Structure Research Articles

Dynamic Analysis of a Large Deployable Space Truss Structure Considering Semi-Rigid Joints

Joints are widely used in large deployable structures but show semi-rigidity due to performance degradation and some nonlinear factors affecting the structure’s dynamic characteristics. This paper investigates the influence of semi-rigid joints on the characteristics of deployable structures in orbit. A virtual connection element of three DOFs is proposed to model the semi-rigid joints. The governing equations of semi-rigid joints are established and integrated into the dynamic equation of the structures. A series of numerical experiments are carried out to validate the proposed model’s accuracy and efficiency, and the deployable truss structures’ static and dynamic responses are analyzed. The results show that semi-rigid joints exacerbate the effects of an in-orbit microvibration on the stability of deployable truss structures. Semi-rigid joints lower the dominant frequencies of structures, leading to a ‘closely-spaced-frequencies’ phenomenon and altering the dynamic responses significantly. The effects of semi-rigid joints on deployable truss structures are long-term and can be used to establish a relationship model between structural performance and service life. Nonlinear effects vary with the external load and depend on the structures’ instantaneous status. These results indicate that semi-rigid joints significantly influence the characteristics of deployable structures, which must be considered in the design and analysis of high-precision in-orbit deployable structures.

Mechanical behavior of thermally-induced shape memory polymer composites thin-wall tube in non-uniform thermal field: Experiments and simulations

Thermally-induced shape memory polymer composites (SMPCs) have the capability to self-deploy when stimulated by a specific temperature. As a basic component of deployable truss structure, SMPCs thin-wall circular tubes will undergo complex non-linear deformation and changing thermal boundary conditions during application. This article aims to research the mechanical behavior of thermally-induced SMPCs thin-wall circular tubes in a non-uniform thermal field. Thermal properties of SMPCs including thermal conductivities and coefficients of thermal expansion are tested as fundamental temperature-dependent parameters. A 500 mm-long SMPCs thin-wall tube is conducted in the flattening-folding-cooling-reheating experiments through a specially manufactured loading apparatus. Combining phase transition theory and Fourier heat conduction, a coupling algorithm is proposed to describe the thermo-mechanical behavior of SMPCs, which is implemented by the user subroutines VUMAT by commercial finite element analysis packages ABAQUS. By comparing the results from the simulation of the non-uniform thermal field, the simulation of the uniform thermal field and experiments, the coupling algorithm is verified, and the effect on SMPCs from the non-uniform thermal field is given.

Deployable truss structure with flat-form storability using scissor-like elements

Deployable structures have received much attention in the building of large structural systems in space due to the limitations in the packaging capabilities of satellites and launch vehicles. Among various categories of deployable structures, deployable truss structures are most commonly used because of their high stiffness and strength. However, deployable truss structures typically have low packaging efficiency. To improve the packaging efficiency of deployable truss structures, this paper proposes a deployable truss structure that can be stored in a flat form. The proposed structure has a high packaging efficiency while preserving the major advantage of conventional deployable truss structures. The deployment motion is analyzed through a kinematic model, and the packaging efficiency is calculated and compared to a conventional deployable truss structure. The dynamic model of the proposed structure is derived and the deployment characteristics are investigated considering the driving force for deployment and gravity. Finally, the feasibility of the proposed structure is demonstrated with a deployment test of the prototype.

Investigation of dynamic characteristics of revolute-jointed beam using cubic nonlinearity

Joint components in complex deployable truss structures on spacecraft show strong nonlinear characteristics, which can produce significant influences on overall dynamic characteristics of jointed beam structure. In this study, the dynamic characteristics of revolute-jointed beam, considering cubic nonlinearity are investigated using describing function method. For the revolute joint, additional degree of freedom at the location of joint is introduced, on which a generalized force is acted to estimate constraint of joint. Then the effectiveness validation of the theoretical model, and the analysis on effects of joint on the natural and dynamic characteristics of jointed beam are presented.

Optimal design and analysis of deployable antenna truss structure based on dynamic characteristics restraints

A new deployable truss structure for large caliber antennas was presented in this work. The deploying process of the deployable structure was studied using the Moore–Penrose generalized inverse matrix method, from which each deploying state of the deployable truss was obtained through numerical simulations. By the geometrical models output by the self-programmed procedure, dynamic characteristics of the deployable structure were investigated in the deploying process. Based on the sensitivity analysis of the eigenvalues of free vibrations, dynamic characteristics and optimal design and analysis of the deployable antenna truss structure were also carried out. As a case, a deployable pantograph was studied using sequential quadratic programming (SQP) optimization method. Finally, to obtain the minimum weight, the deployable structure was analyzed repeatedly and optimized until the dynamic constraints were satisfied. The analytical results illustrate that to obtain the maximal stiffness based on the optimal weight, the thickness of the cube-shaped cross sections tends to be the minimum, whereas the diameter to be the maximum. The methodology proposed in this paper provides an efficient way to achieve optimal design for other kinds of structures.

Single-Layer Deployable Truss Structure Driven by Elastic Components

AbstractThis study proposes a concept of a single-layer deployable truss structure driven by elastic components which is applicable to small satellites. The structure is self-deployable from its st...

A two-dimensional modular deployable truss structure with bistability

In this article, a new concept of two-dimensional modular deployable truss structure is proposed. To eliminate additional needs of containment mechanism, the proposed deployable structure is designed to have bistable characteristics so that it can stay robust both in the stowed and deployed states. The deployment of each module is triggered by the actuation of shape memory alloys. Static and dynamic models of the proposed deployable structure are established to analyze the characteristics and behavior of the system. The packaging ratio of the proposed structure is analyzed in terms of the design parameters. The results of static and packaging efficiency analysis show that the proposed concept has operational flexibility and high packaging efficiency. Verification of the dynamic model is performed based on a comparison of the response of the dynamic model and the actual deployment process of an experimental model; the deployment process is captured using a stereo pattern recognition camera system. It is shown that the established dynamic model can accurately describe the deployment behavior of the proposed structure.

Stiffness and Damping Formulations for Jointed Deployable Space Truss Structure

In this paper, the dynamic behaviors of a elastic rod connected by a joint with clearance of deployable truss structures are investigated. A one-dimensional cantilever with joint support is examined in the deployable truss structure. These formulations consist of the nonlinear joint dynamic stiffness model and damping models are formulated and the dynamic characteristics of free-vibrating structures are estimated. The natural frequency transitions are investigated by considering the contact and noncontact conditions of the clearances, then the formulation of dynamic stiffness model is obtained. The friction models are mathematically formulated and simplified to make them easy to calculate. The impact damping models are formulated using the linear envelope of the time response and it can be negligible when the speed is small. The dynamic characteristics can be estimated by integrating these models and formulations using the energy loss factors. Experimental evaluations show the dynamic characteristics and demonstrate the validity of the formulations.

Deployment Study on a Single-Layer Deployable Truss Structure Driven by Elastic Components

Deployment Study on a Single-Layer Deployable Truss Structure Driven by Elastic Components

Modal Analyses of Deployable Truss Structures Based on Shape Memory Polymer Composites

With large spatial deployable antennas used more widely, the stability of deployable antennas is attracting more attention. The form of the support structure is an important factor of the antenna’s natural frequency, which is essential to study to prevent the resonance. The deployable truss structures based on shape memory polymer composites (SMPCs) have made themselves feasible for their unique properties such as highly reliable, low-cost, light weight, and self-deployment without complex mechanical devices compared with conventional deployable masts. This study offers deliverables as follows: an establishment of three-longeron beam and three-longeron truss finite element models by using ABAQUS; calculation of natural frequencies and vibration modes; parameter studies for influence on their dynamic properties; manufacture of a three-longeron truss based on SMPC, and modal test of the three-longeron truss. The results show that modal test and finite element simulation fit well.

Design and Deployment Analysis of Modular Deployable Structure for Large Antennas

A deployment analysis and experimental study of a novel modular deployable truss structure for deploying and supporting a 28-m-long satellite synthetic aperture radar antenna is presented. Analysis of kinematics and singularity identified four types of singularity configurations. Singularity decoupling analysis indicates that two singularities can occur in the end phase of deployment and prevent complete deployment. A cubic polynomial deployment control strategy and an eccentric shaft design method are suggested to facilitate smooth deployment of the antenna modular deployable truss structure without encountering singularities. The proposed equivalent dynamic analysis method for forecasting driving force shows that the impact of increasing the number of modules is low for drive mechanism A but high for drive mechanism B. Scale model deployment experiments prove that the presented design scheme and deployment analysis theory are feasible. The proposed research can be applied to other large-scale satellite synthetic aperture radar antennas.

Topology structure synthesis and analysis of spatial pyramid deployable truss structures for satellite SAR antenna

Many attentions for structural synthesis are paid to planar linkages and parallel mechanisms, while design novel pyramid deployable truss structure(PDTS) of satellite SAR mainly depends on experience of designer. To design novel configuration of PDTS, a two-step topology structure synthesis and analysis approach is proposed. Firstly, a conceptual configuration of PDTS is synthesized. Weighted graph and weighted adjacency matrix are established to realize topological description for PDTS. Graph properties are then summarized to distinguish differentia between PDTS and other type structures. According to graph properties, a procedure for synthesis conceptual configuration of PDTS is presented. Secondly, join relationship of components in a PDTS is analyzed. Kinematic chain and corresponding incidence/adjacency matrix are employed to analyze join relationship of PDTS. Properties and simplified rules of kinematic chain are extracted to construct kinematic chain. A procedure for construction kinematic chain of PDTS is then established. Finally, with this two-step approach all 11 rectangular pyramid deployable structures whose folded state is planar are discovered and their kinematic chains are constructed. Based on synthesis results, a novel deployable support structure for satellite SAR is designed. The proposed research can be applied to obtain some novel PDTSs, which is of great importance to design some novel deployable support structures for satellite SAR antenna.

Theoretical analysis and experiments of a space deployable truss structure

Recently, the deployable structures fabricated using shape memory polymer composites (SMPC) have been developed for its unique properties such as highly reliable, low-cost, light weight and cost-effective mechanisms compared with traditional deployable structures. Shape memory polymer is a kind of smart materials which can memorize the permanent shape and can recover to original shape when be exposed to external stimulus. In order to eliminating effects of low stiffness and strength of pure shape memory polymer, shape memory polymer composites reinforced by particles, carbon nanotubes and fibers were studied. A deployable truss structure made of SMPC was analyzed and fabricated in this paper. The truss was made of multilayer carbon fiber reinforced epoxy-based shape memory polymer composites. Through DMA tests, the glass transformation temperature and mechanical properties of laminates which consist in deployable truss were obtained. The curves of recovery moment as a function of curvatures were also obtained in this paper. The deployable experiments were carried out in order to verify the rationality of deployable truss model. And the experimental results showed that the trusses fabricated in this paper can unfold smoothly and can also be applied as a space deployable structure in the field of spacecraft.

Effects of joint on dynamics of space deployable structure

Joints are necessary components in large space deployable truss structures which have significant effects on dynamic behavior of these joint dominated structures. Previous researches usually analyzed effects of one or fewer joint characters on dynamics of jointed structures. Effects of joint stiffness, damping, location, number, clearance and contact stiffness on dynamics of jointed structures are systematically analyzed. Cantilever beam model containing linear joints is developed based on finite element method, influence of joint on natural frequencies and mode shapes of the jointed system are analyzed. Analytical results show that frequencies of jointed system decrease dramatically when peak mode shapes occur at joint locations, and there are cusp shapes present in mode shapes. System frequencies increase with joint damping increasing, there are different joint damping to achieve maximum system damping for different joint stiffness. Joint nonlinear force-displacement is described by describing function method, one-DOF model containing nonlinear joints is established to analyze joints freeplay and hysteresis nonlinearities. Analysis results show that nonlinear effects of freeplay and hysteresis make dynamic responses switch from one resonance frequency to another frequency when amplitude exceed demarcation values. Joint contact stiffness determine degree of system nonlinearity, while exciting force level, clearance and slipping force affect amplitude of dynamic response. Dynamic responses of joint dominated deployable truss structure under different sinusoidal exciting force levels are tested. The test results show obvious nonlinear behaviors contributed by joints, dynamic response shifts to lower frequency and higher amplitude as exciting force increasing. The test results are further compared with analytical results, and joint nonlinearity tested is coincident with hysteresis nonlinearity. Analysis method of joint effects on dynamic characteristics of jointed system is proposed, which can be used in optimal design of joint parameters to achieve optimum dynamic performance of jointed system.

Driving Characteristic Analysis of a Planar Deployable Support Truss Structure for Space Antenna

As the development of space structures is increasing fast, analysis on the characteristics of those deployable structures deserve to be paid enough attention to ensure a reliable deployment on orbit. For a deployable truss structure, more than one position can be chosen as the driving positions, especially when the structure has not only 1 degree of freedom (DOF), an available choice of the driving positions shows significant importance on the performance of the space deployable structure. This paper mainly deals with a planar deployable support truss structure for space antenna by means of the closed loop equations and the Kane equation to discuss the deployment characteristics by comparison of the driving torque needed over time. A full comparison of all the possible examples of deployment analysis results under different driving modes is presented. The results show the importance of the choice of driving movements and the design of parameters and also provide a useful reference to other related truss structures.

Mobility and kinematic simulations of cyclically symmetric deployable truss structures

Based on the mechanism of four-fold rigid origami, this study proposes a type of deployable truss structures that consist of repetitive basic parts and retain full cyclic symmetry in the folding/deployment process. On the basis of the irreducible representations and the great orthogonality theorem, symmetry-adapted analysis using group theory is described to identify the symmetry of mobility and kinematic behavior. Equivalent three-dimensional pin-jointed frameworks are employed for the symmetric structures. To verify that the structures can be foldable while retaining their full symmetries, numerical simulations on a series of structures with different symmetries and geometries are carried out. An artificial damping is introduced to stabilize the nonlinear folding behavior with singularity. Symmetry-adapted mobility analysis reveals that the structures of this type can be continuously folded with one degree-of-freedoms. Numerical simulations using the nonlinear iterative method accurately predict the folding behavior, as the results agree very well with the theoretic value.

KINEMATIC ANALYSIS OF THE DEPLOYABLE TRUSS STRUCTURES FOR SPACE APPLICATIONS doi: 10.5028/jatm.2012.04044112

Deployable structure technology has been used in aerospace and civil engineering structures very popularly. This paper reported on a recent development of numerical approaches for the kinematic analysis of the deployable truss structures. The dynamic equations of the constrained system and the computational procedures were summarized. The driving force vectors of the active cables considering the friction force were also formulated. Three types of macroelements used in deployable structures were described, including linear scissor-link element, multiangular scissor element, and rigid-plate element. The corresponding constraint equations and the Jacobian matrices of these macroelements were formulated. The accuracy and efficiency of the proposed approach are illustrated with numerical examples, including a double-ring deployable truss and a deployable solar array.

Kinematic analysis of the deployable truss structures for space applications

The Journal of Aerospace Technology and Management is a techno-scientific publication serialized, edited, and published by the Institute of Aeronautics and Space (Instituto de Aeronáutica e Espaço-IAE).

Spatial Beam Analysis with Large Displacement for Deployable Truss Structures

A formula of multibody finite element analysis based on the corotational formulated finite element method and the direct coordinate partitioning for deployable truss structures is proposed. A beam element used in linear finite element analyses is a basic element in the formula. A corotational frame is defined by node coordinate systems attached to a beam element. A tangent stiffness matrix contains a virtual rotation displacement of the corotational frame. By the appropriate transformation of this virtual displacement, a simple geometric stiffness for the formula is obtained. The formula makes it possible to analyze the deploying motions of large deformed deployable truss structures, to be applicable to general finite elements, and to increase convergence speed of the Newton method in a solution algorithm. This improvement is achieved by neglecting virtual work done by rigid body motion in the process of employing the geometric stiffness to the conventional formula. A validity of this formula is confirmed through results of a numerical deployment analysis of a deployable beam structure.

Effect of Synchronization Errors on Deployment Characteristics of Modularized Structures

This paper describes the deployment characteristics of a modular mesh antenna. The antenna consists of seven modules and is 10 m in diameter. Each module consists of a mesh surface and a deployable truss structure. Three motors cooperate to control the antenna deployment. The synchronization errors caused by asynchronous deployment motion depend on two factors: length of released control cable, and control cable failure. A deployment test is conducted on a 7-module assembly suspended from the ceiling in the cup-down configuration. We measured the displacement of the slide hinge along the center axis, the tensions in the control cables, and the strains in the rib structure members during deployment. We evaluated the effect of synchronization errors on the tension in the control cable and the strain in the rib structure members. We conclude that synchronization errors do not disturb the deployment motion and do not cause any structural failures when all modules are controlled by cables.