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Dynamic Analysis of Deploying Elastic Arms In Interaction With Spacecraft Dynamics

Bagheri Ghaleh, Parisa | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43557 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Malaek, Mohammad Bagher; Abedian, Ali
  7. Abstract:
  8. Dynamic analysis of deploying elastic arms of spacecrafts carrying tip mass has been presented. The research concentrates on the precise analytical simulation to reveal the phenomena which are usually eliminated in estimations. One of the most important factors which affect the dynamic response of such arms is rigid body dynamics of spacecraft. Considering this aspect of the problem the evolutionary analytical simulation has been developed through three steps. The first step focuses on the minute simulation of the arm deployment, in which a new mathematical approach called "elastic profile" has been developed which leads to semi-analytical solutions for the arm carrying tip mass. Furthermore, a new deployment function which represents reality of arm axial motion is derived; the inertial effect of the axial acceleration is taken into consideration through dynamic analysis. In the second part of this work, the effect of rigid body dynamics of the base on the deploying arm dynamics has been studied. The angular motion of the arm base in 3D space which causes the coupling between two lateral elastic displacement of the deploying arm has been investigated in the initial stage and then the orbital motion of a spacecraft having geocentric pointing is considered as the arm base dynamics which causes the coupling of arm elastic dynamics with orbital mechanics of the spacecraft. In this step, the resultant dynamic stiffness and induced loads on the spacecraft due to the arm dynamics are investigated. Furthermore, the effect of some orbital parameters such as orbit eccentricity and spacecraft true anomaly in arm deployment phase are studied in addition to the deployment orientation of the arm with respect to the orbital plane. Finally, in the third step of the research, the dynamics of a spacecraft with limited mass and moment of inertia which its rigid body motion is affected by the arm dynamics is studied through deployment and the interaction between the deploying arm dynamics and spacecraft rigid body motion is investigated which reveals the effect of the spacecraft mass on the energy transfer between elastic arm and spacecraft rigid body motions. In order to crosscheck the results two methods of Assumed Modes with compatible shape functions and Finite Element with variable domain elements are applied through the simulations of this study. Different case studies shed new light on the importance of inertial effects of spacecraft motion on the elastic arm dynamics for space applications where conducting experiments for them is very difficult or impossible.
  9. Keywords:
  10. Three Dimensional Dynamic Analysis ; Deploying Arm ; Orbital Motion ; Inertial Forces

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