Mechanical Properties of Advanced Gravity Gradient Booms
Mechanical Properties of Advanced Gravity Gradient Booms

Author: C. L. Staugaitis

Publisher:

Published: 1970

Total Pages: 44

ISBN-13:

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The mechanical (static and dynamic) behavior of a number of boom designs applicable to gravity gradient and antenna use were investigated. Bending stiffness, critical bending moment, damping, and transverse (fundamental bending) frequency were the principal properties measured. The structural integrity of two boom designs was also evaluated when subjected to cyclic loading conditions. The results are analyzed in terms of structural performance and conformance to elastic behavior as predicted by theory for thin-walled tubes.

Coupled Thermally-induced Transverse Plus Torsional Vibrations of a Thin-walled Cylinder of Open Section
Coupled Thermally-induced Transverse Plus Torsional Vibrations of a Thin-walled Cylinder of Open Section

Author: Harold P. Frisch

Publisher:

Published: 1970

Total Pages: 124

ISBN-13:

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Long thin-walled cylinders of open section (STEM type booms) have been used on many satellites either for experimentation or Gravity Gradient stabilization. Equations for the coupled transverse plus torsional oscillations of a long open section cylinder in direct sunlight are derived. Numerical results show that unstable thermally induced oscillations can be excited solely by the impinging thermal energy of the sun. It is shown that this is a direct result of the boom's extreme weakness in torsion. By literally zippering the boom's open section, to increase its torsional rigidity, the problem can be eliminated. Flight data from OGO IV, V, VI and RAE are cited to support the theoretical findings.