Summary:
This dissertation considers the design of hinges for rigid body hinged deployable
structures for small satellites.
A review of current deployable structures, the features required of hinges
within them and the ability of current hinge designs to meet these requirements
is made. Hinges based on tape-springs (curved elastic strips as found
in tape-measures) are found to be the most suitable as they are lightweight,
simple to manufacture, low-friction, self-locking, self-deploying and give
good latching accuracy.
Analytical predictions of the end-moments required to buckle an offset
tape-spring hinge with two or more tape-springs are made. These are then compared
to finite element predictions and experimental results.
Tape-spring Rolamite hinges, which include a Rolamite hinge connected to
a tape-spring hinge, offer the same advantages as tape-spring hinges whilst
improving the unlatched stiffness of the tape-spring hinge and giving a definite
kinematic opening path. These improvements simplify the modelling of the dynamics
and ground-based testing of any deployable structure made from the hinges.
A new design of tape-spring Rolamite hinge is presented, which incorporates
wires rather than bands, and weighs less than a tenth of previous designs.
Analyses of the deployment moment, buckling moment and
stiffness are made and then compared to experimental tests.
The deployment dynamics of a two panel system with one moving panel connected
by tape-spring Rolamite hinges are investigated. When the effects of air resistance
and the elasticity of the panels were taken into account, the rigid-body
dynamic model showed good agreement with results
measured from experimental tests. A review of damping methods used in deployable
structures and their applicability to structures with tape-spring Rolamite
hinges is presented. The effectiveness of some of these damping methods in
controlling the deployment rate and latching shock is tested.
The design and manufacture of a conical tape-spring Rolamite hinge is presented.
This hinge uses conical rolling surfaces in place of the cylindrical surfaces
commonly used in rolamite hinges. Such a hinge functions as two hinge lines
held at a constant angle to each other with the rotations of each hinge line
constrained to be equal. Initial analytical design guidelines and the
integration of finite element models of tape-springs and three-dimensional
computer aided design are used to overcome the issues raised by the complex
folding geometry of the tape-springs in such a hinge. Rapid prototyping is
used
to create the complex geometry of the hinge.
Finally, a number of deployable structures which include hinges based on
tape-springs are analysed, built and tested. Close attention is paid to the
analysis of the number of mechanisms present within these structures.
[Cambridge University | CUED | Structures Group | Geotechnical Group]