The IMOS computer program contains subprograms that, collectively, provide a unique capability for multidisciplinary analysis of a system represented by a combination of mathematical models of structural (mechanical), control, thermal, and optical characteristics. One example of such a system would be a telescope equipped with an attitude-control subsystem. IMOS enables a user to
- define the geometry of the system,
- build a finite-element mathematical model of the system structure,
- define the system optics in the coordinate system of the finite-element model,
- add control elements to the model,
- add mechanical and thermal disturbances to the model, and
- evaluate the open- and closed-loop performances of the system.
IMOS also includes graphical subprograms that enable viewing of structural-assembly operations, structural deformations, and layouts of optical elements. IMOS is written in MATLAB and can be used on any computer that supports MATLAB. The core subprograms are easily coupled in MATLAB, and the user can write additional MATLAB function subprograms. The additional capabilities afforded by the MATLAB control-design, signal-processing, and optimization "toolboxes" enhance the versatility of IMOS. Also included in IMOS are interface subprograms for optical analysis by the MACOS program, thermal analysis by the TRASYS and SINDA programs, and finite-element modeling by the NASTRAN program.
This program was written by Hugh C. Briggs, Daniel Edred, Robert Norton, Andy Kissil, William Ledeboer, Samuel Sirlin, Marie Levine, Jim Melody, Mark Milman, and Laura Needels of Caltech for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com under the Computer Programs category,or circle no. 171 on the TSP Order Card in this issue to receive a copy by mail ($5 charge).
NPO-20238
This Brief includes a Technical Support Package (TSP).
Program for Analysis of a Complex Optomechanical System
(reference NPO20238) is currently available for download from the TSP library.
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Overview
The document is a technical support package detailing the thermal analysis conducted for the X2000 Gossamer power antenna, a concept aimed at enhancing solar-powered exploration, particularly for a mission to Europa. The antenna, with a diameter of 15 meters, is designed to be composed of inflatable elements that will be deployed and rigidified after launch. Its primary functions include communication and solar concentration for converting solar energy into electrical power.
The analysis focuses on the thermal design requirements necessary to minimize structural distortions in the antenna reflector. Key objectives include maintaining circumferential temperature gradients below 2°C and ensuring that all inflatable elements remain above the boiling point of liquid nitrogen (78 K) for structural integrity. The thermal design employs passive techniques, utilizing materials and coatings that optimize thermal performance.
The thermal model incorporates a geometric and lumped capacitance approach, translated into TRASYS and SINDA formats for detailed analysis. The TRASYS model uses contour integration to determine radiation exchange factors, while TSS (Thermal System Simulation) generates radiation interchange factors through ray tracing. The analysis considers various thermal cases, including hot and cold scenarios, to evaluate the impact of different materials and coatings on temperature management.
The findings indicate that the struts must be constructed from materials with thermal conductivity greater than 10 W/m-°C to meet the required temperature gradient. The reflector's backside is recommended to use a double metalized Kapton coating to enhance thermal performance, particularly on the cold end. The inflatable structures, pressurized with nitrogen, are confirmed to be well within their temperature limits.
Overall, the document outlines the methodologies and results of the thermal analysis, emphasizing the importance of material selection and thermal management in the design of the X2000 Gossamer power antenna. The analysis serves as a foundational step in ensuring the antenna's operational effectiveness in the harsh environment of space, particularly during its mission to explore Europa.
