TPF-C Technology Plan - Exoplanet Exploration Program - NASA

Integrated Modeling and Model Validation
Table 5-2. Characterization and Validation of Basic Physics Models
Technology Description Validation Approach
Material Properties
Nonlinear Mechanics
Collect high accuracy material
properties for critical thermal,
mechanical, and optical analyses.
Include assessment of property
variability, stability, temperature
dependency, wavelength dependencies
Investigate friction models as a
function of pre-load, coeff of friction,
stiffness, hysteresis, temperature
Develop bounding analysis techniques
to predict μdynamics disturbances
Develop error budget for determining
measurement accuracy of test facilities.
Develop new facility where appropriate and
verify results on benchmark materials.
Collect all material property information in
a Project-controlled document.
Validate model sensitivities to driving
parameters on generic friction test article.
Validate μdynamics bounds and system
propagation on generic test article.
This area addresses two sets of particular concerns. The first assures that material properties
relevant to TPF-C will be collected and controlled. Specifically, the data needs to be at levels of
accuracy consistent with the goal of the end metric (e.g., tolerances in picometers of WFE), and
all material property information will be delivered with verified error bars reflecting the test
facilities’ systematic and random errors.
The second area assures that we develop a physical understanding of what drives nonlinear
behavior in mechanisms like hinges and latches or composite subassemblies. A goal is to
develop constitutive mechanism models to include in system analyses and to generate
component-level requirements on flight hardware that will meet the TPF-C specifications. Of
particular importance is the physical understanding of micro-slip, spontaneous energy release,
micro-yield, hysteretic behavior, delayed stress relaxation, and all other nonlinear mechanical
physics affecting the prediction of structural stability to picometer levels. Another goal is the
study of composite material variability and stability, especially at bonded interfaces. Overall,
investigations will be performed to establish scaling laws for predicting sub-nanometer and 0-G
behavior, and to define component level test protocols for model validation of flight hardware in
later phases of the project.
Validate Models and Scalability on Component Testbeds
This area addresses the need to develop and validate component level models on testbeds, as
summarized in Table 5-3.
Technologies described previously in the areas of Tool Development and Physics
Characterization will be incorporated into component level models for validation in the testbeds
addressed herein. Activities under this area include investigation of scaling law when testing
conditions do not match flight environments, validation of the error budget architecture and
sensitivity propagation, evaluation of modeling error sources and validation of uncertainty
propagation methodology, and stitching of the various components and interfaces where
appropriate. Since many of these testbeds are design dependent and will eventually be competed
to industry, there is very little detail available at this time. However, in later sections of this
document, the component testbed descriptions highlight what aspects of model validation will be
verified on a case by case basis.
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