Dynamics Of A Folding Rod Of A
Space Self-deployable Frame
Author(s)
V. N. Zimin & V. E. Meshkovsky
Abstract
Small oscillations of the folding rods under gravity are under consideration. A
Laplace transformation is used so as to obtain the periodic solution. The impact
load was introduced in the differential equation by means of the generalized delta
function.
1 Introduction
When developing large space deployable frames, an investigation of static and
dynamic characteristics of the frame rods is an important point. These
investigations provide the information for calculations of the frame static and
dynamic behavior on a test bench and under working conditions.
Numerous hinges cannot provide a rigid locking of the rods (Fig.1). As the
result, the deployable frame behavior under dynamic loads is simulated by the
motion of a rather complicated dynamic system with non-liner stiffness and
damping properties. Nonlinearity of the frame properties is caused by the
following reasons. The rigidity of the whole structure is determined both by the
rigidities of the rods and by the fact that spring hinges connecting the rods has
stops limiting rotation of the rods relative to each other. Presence of the stops
results in elastic line fracture for the units under consideration. Backlashes in the
hinges have an influence upon the frame rigidity, too. So, the energy dissipation
in the structure is nonlinear because of the damping in the rod hinges.
Nonlinear properties of the frames appear greatly during frequency tests. In
that case, it is reasonable to speak about some frequency ranges corresponding to
the frame natural vibrations. In tests fulfilled for number of structures, this range
was about 0.2 Hz. The more the excitation frequency was increased, the more the
accelerometer amplitude-frequency characteristics became chaotic due to the
Keywords
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