TPF-C Technology Plan - Exoplanet Exploration Program - NASA

Chapter 5
strength of computer simulation and analysis. For such scenarios, system-level mission
confidence can only hope to be achieved via:
• Analyses that are based on computational components whose theoretical formulations,
assumptions, and implementations are well understood at all levels and which are capable of
excellent correlation with available test facility data, to unprecedented levels of numerical
precision.
• Knowledge of the range of applicability of the analyses as a result of necessary
approximations made in the models and computational algorithms themselves.
• A consistent, computationally-based approach to analysis model parameterization and design
space exploration in order to rationally address issues such as error budget limits and the
assurance of optimally-tolerant designs.
The objective of this technology development effort will be to produce a general-purpose,
common-model capability for precise computation of time-dependent optical aberrations
resulting from radiation heat transfer-induced structural deformations. While intended to
complement processes built using commercial off-the-shelf-components, it nevertheless seeks to
fundamentally address issues relating to multidisciplinary analysis model integration in a manner
that fully exploits recent advances in computer science and parallel computing platforms, and is
expected to result in an open, extensible code base that can be used for continued methods
research and development by other programs.
Progress to Date
In an area as rich in commercially available technologies as is finite element-based structural
analysis, development efforts have focused on aspects unique to TPF classes of problems, in
areas unlikely to be addressed in a timely fashion (if at all) by commercial vendors. Recent
developments include:
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• Creation of an open, extensible, large-problem-capable architecture:
In order to adequately address issues relating to transient thermal stability and its effects
on observatory performance, the use of thermal models with discretization levels
approaching those of the structural models is anticipated. In addition to the architectural
demands placed by such a common-model, integrated approach, the desire to readily
extend the code as engineering experience with such systems is gained has led to
development of strongly object-based data structures, core computational modules
written in C, and Matlab-level hosting for robust extensibility on virtually all code levels.
• Integration with existing engineering processes:
To facilitate interchange among engineers at JPL and other NASA centers and
contractors, input to this new code can be specified using fully data-driven formats in
NASTRAN (NAsa STRuctural Analysis) syntax for both model description and solution
control. Though this de facto standard for finite element model description has been
generalized for the new capabilities developed under TPF (and, indeed, other external
code inputs are allowed as well), the approach nonetheless supports the use of existing
CAD tools having NASTRAN-based pre- and post-processors, and should facilitate the
complementary analyses seen as necessary in helping to achieve system-level confidence.
• Thermal and structural finite elements: