Space Engineering Applications Research Articles

Design and analysis of rigid-elastic coupling origami flashers with bistable characteristics

Origami flashers are frequently used in the design of deployable structures due to their large storage ratio and simple structure. However, origami flashers are not foldable without the flexible deformation of the structural components. On the other hand, conventional origami flashers could not be maintained in the deployed configuration with enough supporting stiffness because of the flexibility of the facets and creases, which limits their practical applications. By analyzing the mobility of the rigid origami flashers, we find that the origami flashers have a bistability-like property. Based on this, we propose a method to design rigid-elastic coupling origami flashers with bistable characteristics. The rigid-elastic coupling origami flashers consist of rigid facets, zero-stiffness creases, and elastic ropes. The bistable folding characteristics are analyzed by theoretical models, and demonstrated by numerical methods and experiments. Such bistable characteristics allow for the deployment of the origami with less energy consumption, while achieving greater supporting stiffness in the deployed configuration. The effect of different parameters on the dynamic performance is also investigated. A fabrication method of the novel system is proposed and verified by a physical prototype. The rigid-elastic coupling origami flashers facilitate their potential applications in space engineering.

Design of deployable curved-surface rigid origami flashers

This paper proposes an approach to designing rigid origami flashers that can be deployed onto curved-surface configurations. The method of designing planar origami flashers that can be wrapped around regular polygonal central hubs is presented. Based on the principle of parallel projection, planar origami flashers are projected onto target spherical surfaces to obtain the vertices on the boundary creases between sections of adjacent origami flashers. The geometric relationships of thin-panel curved origami flashers are established in terms of foldability, and other vertices in each section are calculated using numerical methods. Flexible and elastic hinges modify the thin-panel curved origami flashers into thick-panel rigid flashers. The thick rigid panels maintain the shape of flashers, and the flexible creases treated using thickness-accommodating methodologies are used to maintain the foldability of the thick panels. Additionally, we analysed the parameters that affect the accuracy of the surface fitting. The feasibility of the proposed approach is verified using numerical simulations and physical prototypes. The novel designing of deployable curved-surface rigid origami flashers facilitates their potential applicability in solid surface antennas, surface reflectors, and other space engineering applications.

A review of gas-surface interaction models for orbital aerodynamics applications

Renewed interest in Very Low Earth Orbits (VLEO) - i.e. altitudes below 450 km - has led to an increased demand for accurate environment characterisation and aerodynamic force prediction. While the former requires knowledge of the mechanisms that drive density variations in the thermosphere, the latter also depends on the interactions between the gas-particles in the residual atmosphere and the surfaces exposed to the flow. The determination of the aerodynamic coefficients is hindered by the numerous uncertainties that characterise the physical processes occurring at the exposed surfaces. Several models have been produced over the last 60 years with the intent of combining accuracy with relatively simple implementations. In this paper the most popular models have been selected and reviewed using as discriminating factors relevance with regards to orbital aerodynamics applications and theoretical agreement with gas-beam experimental data. More sophisticated models were neglected, since their increased accuracy is generally accompanied by a substantial increase in computation times which is likely to be unsuitable for most space engineering applications. For the sake of clarity, a distinction was introduced between physical and scattering kernel theory based gas-surface interaction models. The physical model category comprises the Hard Cube model, the Soft Cube model and the Washboard model, while the scattering kernel family consists of the Maxwell model, the Nocilla-Hurlbut-Sherman model and the Cercignani-Lampis-Lord model. Limits and assets of each model have been discussed with regards to the context of this paper. Wherever possible, comments have been provided to help the reader to identify possible future challenges for gas-surface interaction science with regards to orbital aerodynamic applications.

High structural insulation composite material development with electromagnetic protection effect reinforced with carbon fibers and particles

Many articles in the literature discuss about the harmful effects of electromagnetic waves emitted by electrical and electronic devices on human health. The composite panels, which are the subject of this study, are designed with the inspiration of the absence of a protective wall covering material from the effects of electromagnetic waves in the market. This study aims to develop a material with electromagnetic insulation as well as heat and sound insulation for especially civil engineering and space engineering applications. In the study, panels are produced by adding carbon fibre and carbon particles into the polyurethane matrix. Heat transmission coefficient tests, sound absorption measurement tests and electromagnetic protection efficiency tests have been made for panels. As a result of the tests, electromagnetic protection values ranging from 22 to 83 dB were obtained from panels and heat transfer coefficient values were found to be less than the standard values of 0.06 W/mK and sound insulation values were found to be having the lowest 0.22 and the highest 0.90 Hz sound absorption coefficient. In addition to the above findings, the composite panels were elastic, lightweight and smooth. Finally, it is determined that the composite panels developed in this study satisfy the conditions required for heat, sound and electromagnetic insulation for engineering applications.

Effects of selectively triggered photothermal particles on shape memory polymer composites: An investigation on structural performance, thermomechanical characteristics and photothermal behaviour

Light-activated shape memory polymer composites (LASMPCs) have the ability to facilitate breakthrough technological advancements in aerospace and space engineering applications since the shape memory effect can be remotely controlled by a light beam. Introduction of rare-earth organic complexes–based photothermal fillers such as Nd(TTA)3Phen and Yb(TTA)3Phen into thermally activated shape memory polymers has been reported as a convenient and commercially available approach to prepare light-activated shape memory polymer composites. Such light-activated shape memory polymer composites undertake selective photothermal stimulation due to light and applicable for macroscale and microscale applications. This article presents the effects of added rare-earth organic complexes of Nd(TTA)3Phen and Yb(TTA)3Phen, as well as glass fibre reinforcements on structural performance and shape memory behaviour of light-activated shape memory polymer composites. The physical and mechanical properties, as well as thermomechanical, shape memory, and photothermal behaviours, were systematically investigated. It has been found that the combination of photothermal fillers and glass fibre reinforcements has enhanced the capacity of light-activated shape memory polymer composites to apply for a wider range of large-scale engineering applications.

Structural performance and photothermal recovery of carbon fibre reinforced shape memory polymer

The shape memory polymers (SMPs) have an interesting capability of keeping a temporary shape and then recovering the original shape when subject to a particular external stimulus. However, due to SMP's relatively low mechanical properties, the use of SMP in a wider range of engineering applications is limited. As such SMPs need to be reinforced before use in engineering applications. This paper presents the mechanical properties, thermomechanical characteristics, photothermal behaviour and light activation of 0/90 woven carbon fibre reinforced shape memory epoxy composite (SMPC) made out of prepreg material. Prepreg is a widely used manufacturing technique for large-scale engineering applications. The experimental results have demonstrated that the structural performance of the SMPC has increased significantly due to carbon fibre reinforcement as anticipated. According to ASTM standard D 3039/D 3039M-00, the mode of tensile failure was identified as “XMV”, where the failure is an explosive type. The dynamic mechanical analysis has revealed that the shape fixity and recovery ratios of the SMPC are 100% and 86% respectively. Under the constrained condition, the stress has been recovered up to 5.24 MPa. The SMPC was exposed to five different power densities of 808 nm and the resultant activation has been systematically investigated. Interestingly, the SMPC has been heated over its glass transition temperature, once it is exposed to a power density of 1.0 W/cm2. Furthermore, the applicability of carbon fibre reinforced SMPC for a deployable solar panel array, intended for remote and localized activation is demonstrated. The SMPC will be a potential candidate for space engineering applications, because of its enhanced mechanical properties and ability of photothermal activation.

Rarefication Effects on Jet Impingement Loads

Rarefication effects on jet impingement loads are studied by comparing recent new formulas at the collisionless flow limit and numerical simulations. The jet exit size is finite, and can be either planar or round. In the simulations, the jets have different degrees of rarefication, with a Knudsen (Kn) number ranging from 0 to infinity; i.e., the jet flows can be continuum, collisional, or collisionless. The comparison results indicate that (1) the new surface load formulas are accurate at the collisionless flow limit; (2) in general, the formulas offer upper limits for the peak loads; (3) however, it is improper to assert that local loads always decrease. The new formulas can offer fast estimations of impingement loads. This may be quite helpful for applications in space engineering by significantly reducing the amount of simulations and experiment costs. Those expressions explicitly include non-dimensional parameters, and their contribution and influence on the loads can be studied in a systematic manner (e.g., with a swift parameter study).

Three-dimensional deployment of electro-dynamic tether via tension and current control with constraints

The concept of space tether has found a great deal of promising applications in space engineering. A prerequisite of any space tether mission is to deploy its tether to a commanded length. This paper aims to achieving the three-dimensional deployment of an electro-dynamic tether system in a propellant-free manner via the feedback control of the tension and electric current in the tether. The proposed controller is formulated in an analytical form with an extremely low level of computational load, and can explicitly account for the physical bounds of the tether tension and electric current by using a pair of strictly increasing saturation functions. In addition, the Lyapunov analysis is made to gain an insight into the stability characteristics of the proposed control strategy. To facilitate the theoretical analysis, the dynamic model of the system is developed under the widely used dumbbell assumption, along with the geomagnetic field modeled using a tilted dipole approximation. Finally, numerical case studies on a representative electro-dynamic tether system are conducted to evaluate the performance of the proposed controller and the influence of the actuating conditions and orbital inclinations.

Stability of the motion near L4 equilateral Lagrangian point

The stability of Lagrangian points in the Earth–Moon system is studied. The problem is carried out when the non-zero eccentricity of the orbits of the two main attracting bodies is taken into consideration. A new criterion to establish stability regions is introduced to aim to be both closer to the Ljapunov definition and suitable for space engineering applications. Some relevant examples are presented.

Nonlinear dynamical characteristics analysis of tethered subsatellite in the presence of offset

The tethered satellite system has potential applications in space engineering, such as retrieval of subsatellites, experiments in microgravity sciences, and radiation measurement in outer space. Nonlinear dynamical characteristics of a tethered subsatellite in the presence of offset are considered. The dynamic equations of the tethered satellite system are derived by using a Lagrangian formulation, in which the main satellite (Space Shuttle) moves in an elliptical orbit and the tethered subsatellite vibrates in the presence of air drag. Linear and nonlinear vibrations and the influence of the tether attachment to the Space Shuttle on the motion of the tethered subsatellite are discussed. The dynamic equations of the tethered satellite system are analyzed theoretically, and some insights are obtained. Finally, numerical results on the tethered subsatellite in different phases of motion are given, and comparisons are made. It has been found that a linear model cannot be used for retrieval, especially in the presence of an offset.

Motion control of free-floating variable geometry truss. II - Inverse kinematics

The inverse kinematics of a free-floating variable geometry truss are formulated in conjunction with the conservation of momentum, and the Moore-Penrose inverse is employed to give the solution. Based on the generalized Jacobian matrix, a two-order solution of task priority is derived, and its possible applications to obstacle avoidance, shape control, and free-endplane control are also discussed. Moreover, the issues of the dynamic singularities of a free-floating variable geometry truss are addressed, and an approach through actively handling the orientation of the free-endplane of a free-floating variable geometry truss is proposed to reduce the coupling of singularities with its dynamic parameters. With the aim of applications in space engineering, a free-floating variable geometry truss model is manufactured and set up in the laboratory, and a distributed control architecture is constructed to provide it with an effective parallel control. Finally, a docking experiment with this model is carried out.

Motion control of free-floating variable geometry truss. I - Kinematics

A variable geometry truss is representative of adaptive structures, whose shape can be intentionally altered through shortening or lengthening its adjustable length members, and so has gained some applications in space engineering including space robots, payload isolation, and so on. A new application of variable geometry trusses is proposed, where variable geometry trusses, as components of some larger space structure, might be expected to construct themselves through their adaptivity. Unlike applications such as space manipulators where a variable geometry truss is considered to be fixed on some platform, in this case a variable geometry truss is free floating in three-dimensional space. To this end, the approach on controlling the motion of a free-floating variable geometry truss is discussed from the standpoint of kinematics. Through taking into account the conservation of momentum of the structural system, a family of compact equations is provided to describe the geometry and motion of freefloating variable geometry trusses. Based on the centroid displacement vector d of a variable geometry truss bay, a group of pseudolinear equations for determining the geometry shape of a free-floating variable geometry truss is obtained. With a simple representation for the angular velocity of a variable geometry truss bay, obtained here, the orientation control for the bay's working plane is made possible. Finally, a simulation is performed to demonstrate the validity of the derived equations.

HZE beam transport in multilayered materials

A nonperturbative analytic solution of the high charge and energy (HZE) Green's function is used to implement a computer code for laboratory ion beam transport in multiple-layered materials. The code is established to operate on the Langley nuclear fragmentation model used in space engineering applications. Computational procedures are established to generate linear energy transfer (LET) distributions for a specified ion beam and target for comparison with experimental measurement. Comparison with 56Fe ion with Pb-Al and Pb-(CH 2) x targets shows reasonable agreement.