Control of vibration of the International Space Station with piezoelectric actuators

Paper number

IAC-05-C2.4.08

Author

Ms. Fabiana di Scioscio, University of Rome "La Sapienza", Italy

Year

2005

Abstract

The International Space Station (ISS), orbiting around the Earth, is subjected to external forces, as can be the impact of meteoroids and man-made debris, that can make the panels vibrate at dangerous frequency that could cause heavy damage. This work want to examine the ability of active material to reduce the vibration in the structural components of the space station.
 
In order to study the dynamic behaviour of the ISS it’s necessary a finite element analysis. The analysed model of the station is a plane structure composed of 85 unidimensional elements (rod), all with the same geometric and physic properties; they are linked in 44 nodes, with 2 degrees of freedom each, in a way to model a reticular system with a central body, 110 Mt in length, and two transversal panels, a superior one of 50 Mt and an inferior of 70 Mt. 

To improve the dynamic characteristics of the structure, e.g. the vibration damping, we use smart structure, made by piezoelectric (PZT) devices.
The use of piezoelectric actuators to control the vibrations of a structure is due to the particular properties of the piezoelectric materials. In fact, when an electric field is applied to these materials, the polarized molecules will align themselves with the electric field, resulting in induced dipoles within the molecular or crystal structure of the material. 
Furthermore, a permanently-polarized material, for example quartz, will produce an electric field when the material changes dimensions as a result of an imposed mechanical force; conversely, an applied electric field can cause a piezoelectric material to change dimensions. All piezoelectric devices/transducers can be described as a kind of capacitor with an electromechanically active dielectric medium: the PZT material.

Changing the number of active actuators and their position on the structure it’s possible to see how the actuators are more efficient to damp the vibrations if activated on the central body. To explain this result it’s necessary to refer to the dynamic response analysis, in which the prevalent oscillations are the ones with low frequency, relevant to the first modes of vibration, right associated to the movement of the central body. 
The aim of this paper is to find the “optimal” position of the piezoelectric devices on the structure in order to obtain a better efficiency and a low power consumption of them.

Abstract document

IAC-05-C2.4.08.pdf

Manuscript document

IAC-05-C2.4.08.pdf (🔒 authorized access only).

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