TPF-C Technology Plan - Exoplanet Exploration Program - NASA

Chapter 4
Figure 4-5. Microslip Tribometer Characterization (MTC) apparatus.
Figure 4-6 Representative data obtained from the Microslip Tribometer Characterization
(MTC) facility.
parasitic effects of cables through pivot or latch joints. Other areas of potential concern include
micro-cracking and residual stress behavior of ULE segments joined through a low-temperature
fusion process, especially as they relate to non-recoverable launch-induced deformations, or
geometric misalignment of sub-assembly elements due to initial fabrication imperfections. This
testbed could also be used to investigate active or passive structural damping technologies,
should there be a need in the future. Details and test plans for the sub-assembly test articles will
be developed as the design and analysis of TPF-C mature and as the understanding of these risks
with respect to the error budget improve.
The test facility will be multi-functional and will be capable of measuring nm-level motions due
to thermal or mechanical disturbances. Tests will range from long-term stability observations to
high frequency measurements, all of which are required to investigate a variety of nonlinear
mechanical physics. For instance, test articles will be tested for quasi-static thermal or
mechanical cyclic loads to identify hysteresis, and for steady-state dynamic loads to characterize
harmonic distortion of the frequency response. When testing hinge and latch assemblies, the
specimens will be turned around in various orientations to investigate and model the effects of 0-
gravity. Alternatively, means to artificially change the pre-load on the frictional interfaces will
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