Search

An airship named “Zhiyuan-1” was designed/fabricated/flied as a technical demonstration for stratospheric airship during 2007–2009 by Shanghai Jiaotong University. The calculation method and procedure of aerodynamic parameters were introduced, and the optimized configuration of the hull and the aerodynamic layout were given in this paper. Wind tunnel tests with different configurations, different pitch angles and different yaw angles were performed to study the wind load characteristics of the rigid model of the airship “Zhiyuan-1” in the O3.2 m wind tunnel at China Aerodynamics Research & Development Center. Also the numerical calculation about the test model was carried out to investigate the aerodynamic behavior. According to the results of wind test and numerical calculation, the excellent hull configuration of the airship “Zhiyuan-1” with lower drag characteristic was confirmed, which is based on optimism of the Michel transition law. And the phenomena of pressure coefficient distribution were discussed according to the results of wind tunnel test and numerical calculation at different flight attitudes.

The prestress developing of tensile cable-net structures is a state transforming process from the initial unstressed state to the final prestressed state, and it is rather complicated because the elastic deformation is normally coupled with the kinematic mechanism movement. Firstly, the basic equations of prestress developing by moving boundary joint are derived from the total potential energy equation. Secondly, the presumed initial tension is proposed to impose into the elements and avoid the singularity of global stiffness matrix. And the self-stress mode which is calculated from the equilibrium matrix with singular value decomposition is employed as basically presumed initial tension. By applying boundary movement increment, an iterative computation is developed to calculate the updating geometric configuration and tension evolution. Finally, the MATLAB program is coded from the presented method, and numerical examples indicate that this computational method is effective and has theoretical significance and valuable guide to design and construction of tensile cable-net structure.

The stowing and deploying experiment was conducted for three 700 mm long thin-walled tubes, and the structural behavior characteristics parameters were measured clearly, including strain, deformation and wrapping moment. 3D finite element models (FEM) were built subsequently and explicit dynamic method was used to simulate the stowing and deploying of the lenticular carbon fiber reinforced polymer (CFRP) thin-walled tubular space boom, which was designed as four-ply (45°/ − 45°/45°/ − 45°) lay-up. The stress and energy during the wrapping process were got and compared with different wrapping angular velocity, the reasonable wrapping angular velocity and effective method were conformed, and structural behavior characteristics were obtained. The results were compared and discussed as well, and the results show that the numerical results by 0.628 rad/s velocity agree well with the measured values. In this paper, the numerical procedure and experimental results are valuable to the optimization design of CFRP thin-walled tubular space boom and future research.

Numerical simulation of forming process is an issue that finds the solution of a series of unstable equilibrium states of cable-strut tensile structures with specific unstressed length. This is a long well unsolved theoretic question, which mostly lies in the couple of mechanism and elastic deformation. On the basis of the unstressed length, the theoretic parabolic curve element was adopted to simulate the cable with elastic tension and deformation. The vector of unbalance nodal force was subsequently formulated with the explicit branch-node matrix of topology in force-density method. And the dynamical relaxation method was used to solve the nonlinear equation to avoid the singular stiffness of equation. Numerical examples indicated that the proposed algorithm could calculate the unstable equilibrium state and simulate the forming process with the unstressed length of the active cables changing, and has some theoretical significance.

The presence of wrinkles in the membrane is the main factor to induce the reflector surface inaccuracy of the space inflatable antenna. Based on the commercial finite element package ABAQUS, a numerical procedure for membrane wrinkle analysis was set up and used to analyze a space inflatable antenna which was under inner pressure to evaluate its wrinkle characteristics. First, the inner pressure effect on the reflector’s wrinkle pattern was studied thoroughly. As inner pressure increases, both the number and the amplitude of the wrinkles decrease, but the total deformation of the whole reflector surface increases much. Second, the influence of the interactions between antenna’s parts was investigated comprehensively. Any kind of unwanted interaction deteriorates reflector’s wrinkle characteristics. The works are valuable to the development and research of the space inflatable antenna.

The presence of wrinkles in a membrane is the main factor that induces surface errors on space planar film reflectarrays. Based on the commercial finite element (FE) package ABAQUS, a numerical procedure for membrane wrinkle analysis was set up, and used to analyze a square planar film reflect-array under pure shear force to evaluate its induced wrinkle characteristics. First, the effect of shear force on the wrinkle pattern of the array was studied and validated by experiment. Second, the effect of prestress was studied. When the prestress increases, the quantity of the wrinkles increases, and the amplitude of the wrinkles decreases. Third, the influence of the boundary conditions was investigated. A frame side edge structure has a relatively smooth surface, but also relatively high stress. Finally, the behavior of a joint seam was analyzed. The results indicate that a joint band has a significant influence on the wrinkle pattern of the membrane.

Nine kinds of structure systems were proposed for the flexible airship according to the inherent structural characteristics. On the basis of equilibrium configuration of the floating airship subjected to the ascent helium buoyancy and gravity, the structural analysis procedure was developed and the computation models were presented for the airship. Then the systematic numerical analysis was carried out for a 25m long airship, the comparison of principal stress of envelope was performed between the nonlinear numerical analysis result and the engineering elastic theory result. The structural performances were evaluated thoroughly. Finally, the reasonable structural systems were proposed. Accordingly, the results herein were valuable to structural design for flexible airship especially for large flexible airship.

S TRATOSPHERE airships have an enormous potential as platforms for different purposes such as monitoring, transportation, telecommunication, and so on [1–5]. For the purpose of verifying some core technologies of stratosphere airship, the remote and autonomous control fuel-cell-powered ZHIYUAN-1 airship (see Fig. 1) was manufactured at the School of Aeronautics and Astronautics of Shanghai Jiao Tong University, China, in 2009. This airship serves both as a reference configuration for theoretical investigations and as a flying test platform for studies in aerodynamic, flight mechanics and control, aeroelasticity, structural design, and fuel cell propulsion systems. The aerodynamic characteristics of the airship are very important for the designs of control system and propulsion system. The conventional configuration layout of the airship consists of the hull, fins, and gondola. The studies of part aerodynamics and interfaces are very important for the aerodynamic configuration layout design of airship. Moreover, the availability and accuracy of aerodynamic calculation methods such as computational fluid dynamics and panel-boundary methods need verify for these airship configurations at low-speed and high Reynolds number conditions. For these reasons, the wind-tunnel tests of scale ZHIYUAN-1 airship were performed. The dimensions of the real and scale ZHIYUAN-1 airship as the experimental model in the wind-tunnel tests are shown in Table 1. This paper is organized as follows: The test facilities and windtunnel models are described in Sec. II. In Sec. III, experimental investigations on scale ZHIYUAN-1 airship are presented. In final section, we draw some conclusions on aerodynamic characteristics of general layout airship configurations.

Airship shape is crucial to the design of stratosphere airships. In this paper, multidisciplinary design optimization (MDO) technology is introduced into the design of airship shape. We devise a composite objective function, based on this technology, which takes account of various factors which influence airship performance, including aerodynamics, structures, energy and weight to determine the optimal airship shape. A shape generation algorithm is proposed and appropriate mathematical models are constructed. Simulation results show that the optimized shape gives an improvement in the value of the composite objective function compared with a reference shape.

The tensile cable-strut structure is a self-equilibrate pre-stressed system. The initial pre-stress calculation is the fundamental structural analysis. A new numerical procedure was developed. The force density method is the cornerstone of analytical formula, and then introduced into linear adjustment theory; the least square least norm solution, the optimized initial pre-stress, is yielded. The initial pre-stress and structural performances of a particular single-layer saddle-shaped cable-net structure were analyzed with the developed method, which is proved to be efficient and correct. The modal analyses were performed with respect to various pre-stress levels. Finally, the structural performances were investigated comprehensively.