Asynchronous Phenomenon of the Ring Truss Deployable Antenna

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.170-173.3415 ◽

2012 ◽

Vol 170-173 ◽

pp. 3415-3418

Author(s):

Xin Yan Wu ◽

An Ping Luo

Keyword(s):

Friction Factor ◽

Supporting Structure ◽

Constraint Equations ◽

Deployable Structure ◽

Tensile Forces ◽

Cable Drive ◽

Deployment Dynamics ◽

Design And Manufacture

The deployable structure of the ring truss have advantage properties, which can be used as an effective supporting structure of deployable antenna. The deployable experiment of ring truss antenna showed that there was asynchronous phenomenon at the course of the deployment. Dynamics theory including constraint equations and considering friction factor are built firstly. Then simulation is studied systematically for the deployment process of ring truss deployable antenna. At last, the conclusions are obtained that the friction insulted in tensile forces of the cable drive decrease and the asynchronous phenomenon in the process of the deployment. It will give some help to the design and manufacture of the ring truss antenna.

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A New Flexible Multibody Dynamics Analysis Methodology of Deployable Structures with Scissor-Like Elements

Chinese Journal of Mechanical Engineering ◽

10.1186/s10033-019-0391-1 ◽

2019 ◽

Vol 32 (1) ◽

Cited By ~ 1

Author(s):

Qi’an Peng ◽

Sanmin Wang ◽

Changjian Zhi ◽

Bo Li

Keyword(s):

Multibody Dynamics ◽

Flexible Multibody Dynamics ◽

Dynamics Analysis ◽

Deployable Structures ◽

Constraint Equations ◽

Deployable Structure ◽

Analysis Methodology ◽

Flexible Multibody ◽

Nodal Coordinates ◽

Element Characteristic

Abstract There are vast constraint equations in conventional dynamics analysis of deployable structures, which lead to differential-algebraic equations (DAEs) solved hard. To reduce the difficulty of solving and the amount of equations, a new flexible multibody dynamics analysis methodology of deployable structures with scissor-like elements (SLEs) is presented. Firstly, a precise model of a flexible bar of SLE is established by the higher order shear deformable beam element based on the absolute nodal coordinate formulation (ANCF), and the master/slave freedom method is used to obtain the dynamics equations of SLEs without constraint equations. Secondly, according to features of deployable structures, the specification matrix method (SMM) is proposed to eliminate the constraint equations among SLEs in the frame of ANCF. With this method, the inner and the boundary nodal coordinates of element characteristic matrices can be separated simply and efficiently, especially on condition that there are vast nodal coordinates. So the element characteristic matrices can be added end to end circularly. Thus, the dynamic model of deployable structure reduces dimension and can be assembled without any constraint equation. Next, a new iteration procedure for the generalized-α algorithm is presented to solve the ordinary differential equations (ODEs) of deployable structure. Finally, the proposed methodology is used to analyze the flexible multi-body dynamics of a planar linear array deployable structure based on three scissor-like elements. The simulation results show that flexibility has a significant influence on the deployment motion of the deployable structure. The proposed methodology indeed reduce the difficulty of solving and the amount of equations by eliminating redundant degrees of freedom and the constraint equations in scissor-like elements and among scissor-like elements.

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Dynamics Analysis of Deployable Structures considering a Two-Dimensional Coupled Thermo-Structural Effect

International Journal of Aerospace Engineering ◽

10.1155/2018/1752815 ◽

2018 ◽

Vol 2018 ◽

pp. 1-10

Author(s):

Qi’an Peng ◽

Sanmin Wang ◽

Bo Li ◽

Changjian Zhi ◽

Jianfeng Li

Keyword(s):

Optimization Design ◽

Control Process ◽

Axial Direction ◽

Structural Effect ◽

Dynamics Analysis ◽

Two Dimensional ◽

Deployable Structures ◽

One Dimensional ◽

Deployable Structure ◽

Deployment Dynamics

The deployment accuracy of deployable structures is affected by temperature and flexibility. To obtain the higher accuracy, various measures such as the optimization design and the control process are employed, and they are all based on deployment dynamics characteristics of deployable structures. So a precise coupled thermo-structural deployment dynamics analysis is important and necessary. However, until now, only a one-dimensional thermal effect is considered in the literatures because of simplicity, which reduces the accuracy of the model. Therefore, in this paper, a new model coupling mechanical field with a temperature field is presented to analyze the deployment dynamics of a deployable structure with scissor-like elements (SLEs). The model is based on the absolute nodal coordinate formulation (ANCF) and is established via a new locking-free beam element whose formulation is extended to account for the two-dimensional thermally induced stresses due to the heat expansion for the first time. Namely, in the formulation, the thermal influences are along two-dimensional directions, the axial direction and the transverse direction, rather than along a one-dimensional direction. The validity and precision of the proposed model are verified using a flexible pendulum example. Finally, the dynamics of a linear deployable structure with three SLEs modeled by the element is simulated under a temperature effect.

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A Shelved Structure for the Support of An Electron Optical Column

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100068825 ◽

1970 ◽

Vol 28 ◽

pp. 366-367

Author(s):

P.H. McLaughlin

Keyword(s):

Electron Source ◽

Floating Platform ◽

Supporting Structure

A shelved structure for the support of an electron optical column affords advantages both to the designer and the user. A lens may be removed for cleaning for example, without demounting the remaining lenses. A custom device for another example, may be placed on a shelf, substituting for the standard lens perhaps so that some specialized research may be undertaken. Especially advantageous is a shelved arrangement if the column assembly is designed to hang from a supporting structure such as a gas borne floating platform, as is the case with the system described below.As shown on the schematic, a floating platform (I) supports the electron source apparatus (2) and a U-shaped column support shelf (3). The column support shelf acts as a key for locating and supporting three struts (4) which with nuts (5) support the condenser shelf (6), the objective shelf (7), the upper projector shelf (8), and the lower projector shelf (9).

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