Stability and Dynamic Analysis of the SET (Short Electrodynamic Tether)

Space-tethers are very slender and flexible structures that are deployed in space. In recent times space-tethers have been the object of numerous studies in the field of astronautics. One of such structures is the SET (Short Electrodynamic Tether). The distinguishing characteristic of the SET is that it orbits with the axis of smallest moment of inertia normal to the orbit plane. The SET is in continuous rotation around this same axis, which allows it to maintain the aforementioned operating position. In most other cases, space-tethers orbit within the orbit plane. The SET is not perfectly straight after deployment. This fact could make the rotation unstable from the structural point of view, as predicted by the linear study of unbalanced rotors (supercritical velocities). However, if non-linear terms in the elastic and internal damping forces are considered in the model (hysteresis causes instability) the resulting motion of the structure could remain bounded. This assertion was shown in a previous study by the authors, through dynamic simulations of the system. In order to confirm these results, the present paper studies the stability of the SET’s solutions. A modified Jeffcott model will be the object of this study. The paper will end with a comparison of the results obtained with those rendered by previous works.Copyright © 2003 by ASME