Truss Antenna Research Articles

Structural design and surface networking analysis of a truss antenna based on hexagonal frustum deployable mechanism units

With the development of space technology, deployable mechanism has been widely applied in large aperture space antennas. In this paper, a hexagonal frustum deployable antenna unit and an innovative modular assembling concept are proposed for large parabolic truss antenna. Screw topology diagram and screw constraint matrix are established to solve degree of freedom (DOF) of the antenna mechanism. By separating column vectors of screw constraint matrix, whole actuations of antenna mechanism are obtained according to unique solution condition. A new hexagon antenna network method based on hexagon frustum units and rotation transformation matrix is proposed, and correctness and efficiency of the modeling principle are proved by simulation. Finally, a prototype of the proposed hexagonal frustum truss deployable antenna mechanism is constructed, and a deployment experiment is conducted, which demonstrate the mobility and deployment performance of the mechanism. The mechanism proposed in this paper provides a theoretical reference for the parabolic truss deployable antenna mechanism, which is potentially valuable in the application of large aperture deployable antennas.

Design, kinematics and dynamic analysis of a novel double – scissors link deployable mechanism for space antenna truss

A novel truss deployable mechanism composed of scissors links is proposed in this paper. First, the geometry analysis of the general single modular unit of truss deployable antenna and the construction of the planar double scissors link mechanism module is conducted. The entire antenna is prepared by connecting the single module in a circular configuration. Using the Gruebler's method, the mobility of the double scissors link truss deployable module is proved equals to 1. Furthermore, based on the Newtonian approach, kinematic characteristics of the double scissors link truss deployable mechanism are examined. The velocities and accelerations of the antenna components obtained analytically are validated through simulations in MATLAB, SolidWorks and ADAMS. In addition to this, the forces, torques and bearing stresses involved in various struts and joints are calculated to ensure that the operation is within the yield limits. The dynamic characteristics of the antenna i.e., acceptable natural frequency is calculated by developing a 10 DoF vibration model. The analytical equations are solved using MATLAB, and the results are validated through simulations in ANSYS Workbench. The novel antenna assembly gives the natural frequency response of 0.0652 Hz with a 1.6 % error. The proposed double scissors link truss deployable mechanism shows storage ratio of 1 and 10.2 along vertical and radial directions respectively. The dynamic response and storage ratio of novel assembly is validated with results in literature. The research lays the foundation for the kinematics and dynamics analysis of other space deployable mechanisms.

Experimental Investigation of Deployment Process of Large Hoop Truss Antenna for Space

Experimental Investigation of Deployment Process of Large Hoop Truss Antenna for Space

Dynamic Modeling and Theoretical Analysis of Planar Nonlinear Vibrations of an Articulated Hoop Truss Antenna

The dynamic behaviors of large-scale hoop truss antennas (HTAs) are significantly influenced by the nonlinear torque transmission properties of flexible hinges. Due to the nonlinearity of the hinge, the HTA can be easily excited to exhibit internal resonances that result in the energy exchange between the adjacent two or three modes. This paper focuses on the 3:1 internal resonant responses of an articulated HTA induced by the nonlinearity of the hinge. The analytical modes are obtained by using the global mode method (GMM) and are validated by finite element method (FEM). Then the partial differential equations (PDEs) of planar motions are discretized into ordinary differential equations (ODEs) by Galerkin’s technique. The multiple time scale method is employed to obtain the four-dimensional modulation equations of the HTA with primary and 3:1 internal resonance. By using the Newton–Raphson iteration and the pseudo arclength continuation, frequency–response and force–response curves are obtained to investigate the theoretical steady-state vibrations of the HTA. Moreover, the influence of the cubic spring stiffness, damping, and external excitation amplitude on the system’s nonlinear dynamic behaviors are investigated. The numerical simulation reveals that the articulated multi-beam hoop structure exhibits typical nonlinear phenomena such as hardening-spring type characteristic, jumps, bi-stability, and double peaks. The research findings contribute to the reliable structural design and vibration control of the articulated hoop truss antenna.

Thermal field simulation and material parameter optimization for spaceborne annular truss antennas

The operational efficacy of large spaceborne annular truss antennas in orbit is significantly influenced by solar irradiation and alternating Earth shadow. This antenna system periodically encounters diverse extreme environments that impact the precision of the antenna surface performance. Consequently, this study presents an optimized thermal control design and conducts temperature field simulation calculations for such antennas. Initial efforts are directed toward analyzing the variables influencing the antenna structure’s temperature, with specific attention paid to the distinctive compositional characteristics of high-precision antennas. As a subsequent step, orthogonal tests are implemented, facilitating the development of an antenna thermal analysis model. This model assists in the identification of principal variables influencing the antenna’s temperature field. Finally, the antenna’s optimal thermal design is drawn upon the biogeography-based optimization (BBO) algorithm, enabling the derivation of ideal material parameters for the thermal design of the antenna. This methodology offers theoretical guidance for future thermal control design of large spaceborne annular truss antennas.

Optimization of a novel, bidirectional, double-ring, deployable mesh antenna with a super-large aperture

The development of large antennas deployable in space is particularly important. A mesh antenna would be ideal because of its high surface accuracy and storage ratio. Here, we develop a novel, double-ring, deployable mesh antenna, then perform mass evaluation and modal analyses. The antenna exhibited better stiffness and a greater storage ratio, compared with typical mesh antennas. However, the mass was excessive. To overcome this problem, we designed a lightweight 5-m truss antenna, then measured its stiffness and strength. We optimized the computer-aided design of a mesh antenna with a super-large aperture, and we performed form-finding analysis of the cable-net. The new antenna included bidirectional deployment and exhibited a greater storage ratio and stiffness, compared with the conventional AstroMesh antenna. The first-order natural frequency was twofold greater than that of the AstroMesh antenna. Our work will aid fabrication of antennas with super-large apertures.

Thermal-dynamic coupling analysis of space truss antennas in actual space thermal environment

Space truss antennas may undergo thermally induced vibration due to temperature changes caused by thermal mutations in the space environment, which will result in antenna performance degradation or even vibration failure. This paper aims to investigate the thermal-structural coupled dynamics of a space truss antenna in the orbital space thermal environment. A spatial thermal analysis model is established based on the spatial heat flux model, Fourier-temperature element, finite element method (FEM) and astrometric model to calculate temperature variation of the antenna structure during its operation in orbit. In this model, the effective solar heat flux received by the antenna structure is calculated on the basis of an astrometric model, with consideration of the Earth's shadow effect and the shading effect of the reflective surfaces. Additionally, a thermo-structural coupled dynamic model of the antenna structure is constructed considering the coupled effects of structural deformation and absorbed effective solar heat flux, which was validated using a finite element shell model. Numerical cases are arranged to comparatively analyze the thermal-structural coupling effects, light shading by reflective surfaces, and thermodynamic response during the space operation cycle, respectively. It is demonstrated that both the earth shadow effect and the shading effect of components have great effect on the temperature distribution and variation of the antenna structure. Moreover, significant vibrations will occur at certain moments especially when the thermal radiation flux to the structural components changes suddenly due to light shading from the earth shadow and reflective surfaces. The thermal-structural coupling dynamic model of the antenna structure presented in this work can provide guidance for thermal compensation and thermal-induced vibration attenuation of truss antenna structures.

A Large-Scale Sensor Layout Optimization Algorithm for Improving the Accuracy of Inverse Finite Element Method.

The inverse finite element method (iFEM) based on fiber grating sensors has been demonstrated as a shape sensing method for health monitoring of large and complex engineering structures. However, the existing optimization algorithms cause the local optima and low computational efficiency for high-dimensional strain sensor layout optimization problems of complex antenna truss models. This paper proposes the improved adaptive large-scale cooperative coevolution (IALSCC) algorithm to obtain the strain sensors deployment on iFEM, and the method includes the initialization strategy, adaptive region partitioning strategy, and gbest selection and particle updating strategies, enhancing the reconstruction accuracy of iFEM for antenna truss structure and algorithm efficiency. The strain sensors optimization deployment on the antenna truss model for different postures is achieved, and the numerical results show that the optimization algorithm IALSCC proposed in this paper can well handle the high-dimensional sensor layout optimization problem.

3D-spatial vibration global modes of a flexible arm-supported ring antenna and its dynamic analysis

Due to the complexity and high degrees of freedom of the structure, dynamical modelling of ring truss antenna (RTA) is a challenging job. The three-dimensional (3D) vibration of each component of RTA is spatial and coupled to each other, and thus assumed modes cannot depict its vibration accurately and dynamical models obtained by FEM generally have high dimensions, by which it is very hard to either conduct dynamical analysis or design its vibration controller. To overcome these obstacles, a dynamical modeling method named the 3D-Global Mode Method is proposed to obtain the low-dimensional analytical dynamical model of a flexible arm-supported ring antenna (ASRA) that vibrates spatially. The natural characteristics of a RTA is investigated by simplifying it as a flexible arm-supported closed multi-beam structure. Natural frequencies and the corresponding analytical 3D global modes are obtained by solving the eigen-equation formed by the spatial matching conditions and the boundary conditions. Orthogonality relations of the 3D analytical global modes are established and then used to transform the partial differential equations of spatial motion into a set of reduced-order ordinary differential equations. Taking the simulation results obtained from the FEM as a reference, the validity of the proposed method is verified by comparing the natural frequencies and 3D global mode shapes with those obtained from FEM. The mode localization phenomenon of ASRA is found and the influence of the parameters of RTA on mode characteristics is investigated. Through the proposed model, dynamical responses of the ASRA excited by orbital maneuvering acceleration are simulated numerically. This study paves an effective way to obtain the analytical global modes of spatially vibrating ASRAs and other similar spatial flexible combined structures, and to establish the low-degree-of-freedom dynamical model.

Fracture failure analysis and prevention of carbon fiber thin wall crossbar

The fracture failure of a crossbar occurred in a routine deployment test of a satellite ring antenna truss structure. In this study, the fracture cause of the carbon fiber thin wall crossbar was analyzed using body microscope observation, scanning electron microscope observation, metallographic analysis, hardness analysis, XRD analysis, and other methods. The analysis results show that the failure bar had interlaminar damage and local crack or breakage before this deployment test. This defect has further expanded and intensified in the multiple deployment tests of the circular antenna, resulting in the gradual decline of the local stiffness of the crossbar, and finally the buckling failure. By using the bottom plate reflection method to carry out non-destructive testing on the rod, it can effectively avoid false inspection and missing inspection of defects.

Active control of large space antenna truss structures using the equivalent beam model

Active control of large space antenna truss structures using the equivalent beam model

Equivalent Beam Model and Improved Structure Design of Large Space Antenna Truss With Geometric Nonlinearity

AbstractThis paper proposes a extend linear equivalent method that can extend the linear equivalent micropolar beam model to the nonlinear equivalent micropolar beam model to analyze nonlinear vibration for large space truss structure, and also proposes a lattice enhancement method to improve the cantilever truss for the buckling problem that exists in space cantilever truss structures. The nonlinear equivalent model is obtained by introducing a corotating coordinate system into the linear equivalent beam model. Since the instability of the fixed root end of the cantilever truss is the main reason for buckling, the method of strengthening the longeron of the truss lattice by lattice is proposed. The accuracy of the equivalent geometric nonlinear model and the effectiveness of the improved cantilever truss structure are verified by four numerical simulation examples. The methods proposed in this paper provide some reference for studying the dynamics analysis of large space trusses and the design of structures.

Multiobjective Optimization Design of Truss Antenna

During the design and manufacturing process of the truss antenna, the surface accuracy of the truss antenna is inherently affected by tolerance. An appropriate optimal design of the truss antenna structure is important to improve surface accuracy. In order to receive the optimal design of the truss structure, this paper adopts the multiobjective optimization algorithm based on an approximate model to optimize the tolerance model with random error. Firstly, considering the influence of the processing and assembly errors of the members on the surface accuracy of the structure, the equilibrium state equation of the truss is established by the principle of minimum potential energy. Then, the relationship between the tolerance and the surface accuracy is obtained by the Monte Carlo method. For improving the computing efficiency of the Monte Carlo method, an approximate model of the truss antenna unit is established, where the rod length tolerance is set as the design variable, and the truss surface accuracy and processing cost are set as the objective functions. Finally, tolerance optimization is carried out by using the multiobjective genetic algorithm. The results indicate that the Pareto solution is obtained with an error less than 10%. Moreover, a set of solutions of the tolerance are obtained which can meet different antenna design requirements. And the results show that the influence of the web rod is significantly greater than that of the bottom rod on the surface accuracy of the structure.

Configuration synthesis and unfolding stiffness characteristics analysis of a truss antenna connecting mechanism based on URU-RR-URU hexagonal deployable unit

• A method of configuration synthesis of deployable connecting mechanism is proposed. • Simulation analysis method is used to determine the stiffness of the driving spring. • The motion principle of the modular mechanism based on URU-RR-URU unit is simulated. • Two deployable mechanisms are compared and discussed. • A prototype with high deployment rate is developed and experiments are conducted. The networking connection mechanism between deployable units is the key to realize large deployable antennas. Considering the RRR-RR-SRS and URU-RR-URU hexagonal deployable units, a method of configuration synthesis for deployable antenna connecting mechanism is proposed. First, according to the hexagonal and triangular combined units’ division of the parabolic reflector and based on screw theory, a method of configuration synthesis for connecting mechanism of a modular mechanism is proposed, and two modular mechanisms are obtained. Next, the motion principle of the modular mechanism, based on a spring actuation URU-RR-URU unit, is simulated, while simulation analysis method is used to determine the spring stiffness . The structure composition, motion characteristics and deployment rate of the two mechanisms are compared and analyzed. Finally, the modular deployable mechanism, able of complete folding, is selected, while the unit prototype and one-circle modular prototype are developed for validation experiments regarding the correctness of the presented theoretical analysis. The results provide a theoretical basis for the design and application of the supporting mechanism of large deployable antennas with high deployment rate.

Deployment Strategy and Dynamic Analysis of Large Ring Truss Antenna

The deployment strategy and dynamic analysis of the AM-2 AstroMesh ring truss antenna reflector are studied in this paper. The rigid multibody dynamic models of the truss structures with alterable and fixed diagonal length are established, respectively, by using the natural coordinate formulation (NCF). The driving scheme and the synchronous constraint scheme are proposed for two types of truss structure, respectively. The degree of freedom (DOF) analysis of the truss structure is carried out according to the redundant constraint processing method. The deployment strategies of the two different types of truss structures are discussed. The dynamic simulation of the deployment of a 30-side AM-2 AstroMesh reflector truss structure with fixed diagonal length without gravity is carried out. The deployment characteristics of the truss structure are obtained. The driving forces are predicted according to the dynamic simulation.

Local bifurcation of a circus truss antenna considering the effect of space thermal excitation

The local stability and bifurcation of a circus truss antenna under the influence of the thermal excitation are considered using both analytical and numerical methods. On the basis of the obtained four-dimensional averaged equation with 1:2 internal resonance, a kind of eigenvalues of the bifurcation response equation is investigated. By take advantage of the central manifold theory, nonlinear transformation and Routh-Hurwitz criterion, the stable conditions of the equilibrium points are obtained. Finally, the numerical simulations obtained by Runge-Kutta method illustrated the theoretical analysis results.

Stability Analysis and Nonlinear Vibrations of the Ring Truss Antenna with the Six-Dimensional System

Stability Analysis and Nonlinear Vibrations of the Ring Truss Antenna with the Six-Dimensional System

Deployment Impact Experiment and Dynamic Analysis of Modular Truss Antenna

The deployment of a modular truss antenna reflector is relied on the driven energy of the springs between the components of the structure. The deployment process is characterized by fast speed and large impact. In order to study the impact characteristics of antenna deployment on the boundary, the deployment dynamic analysis of a modular truss antenna reflector is carried out. The deployment impact experiment is performed to obtain the impact forces of the reflector on the boundary. The dynamic model of the modular truss reflector is modified according to the experiment results. The dynamic analysis of a satellite with an arm and a modular truss reflector is conducted by using the modified reflector model. The dynamic behavior of the satellite in orbit during the modular truss antenna reflector deployment is predicted.

Application of Stewart Platform in the Low-Frequency Vibration Characteristic Test of Space Truss Deployable Antenna on Satellite

The space truss deployable antenna has low natural frequency, multi-closed-loop, and multiredundant structure characteristics, which is a kind of flexible antenna. It is hard to obtain the vibration characteristics under low frequency by finite element analysis or conventional shaking table test. To verify the structure characteristics of the antenna in the folded state below 2 Hz, a low-frequency vibration system is established based on the 6-DOF Stewart platform. Rotation matrix analysis method was adopted to obtain the platform’s velocity and acceleration characteristics. Then, a low-frequency vibration test was carried out on the platform. The results show that the natural frequency of the antenna is 1.51 Hz and the maximum dynamic displacement is 140.6 mm, which provides a certain foundation for the further development of the space truss antenna.

Dynamic modeling and analytical global mode shapes of a folded beam-ring structure for a truss antenna reflector with two arms

The large-aperture hoop truss antenna is considered as an ideal deployable antenna, whose dynamic performance largely limits the practical application. Extracting a reasonable and solvable model is the essential prerequisite and foundation for analyzing the dynamic characteristics of an antenna. In this paper, a folded beam-ring structure composed of two beams and one ring is proposed to model a hoop truss antenna. The governing equations of motion and boundary conditions for the folded beam-ring structure are derived by using the Hamilton principle. After applying the method of separation of variables, the frequencies and global mode shapes are theoretically calculated by solving the linear parts of governing equations and boundary conditions. The reliability of dynamic model proposed for the folded beam-ring structure is proven by comparison of frequencies and mode shapes. The influences of geometrical and physical parameters on natural frequencies of folded beam-ring structures are analyzed. The parametric rule of frequencies is important for analyzing the resonant relations of the structure. The analytical global mode shapes are beneficial for constructing precise nonlinear dynamic model for the antenna system. And the modeling method presented here can be used as a reference to dynamic analyses of other complex structures.