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SINDA/G has been integrated transparently into the FEMAP FEA/CAD modeling environment. Although FEMAP is widely used for structural modeling, the user interface displays primarily thermal boundary conditions and thermal material properties when in the SINDA/G thermal modeling mode. All SINDA/G options are selected from dialog boxes. Complex thermal modeling involving forced and natural convection using standard nondimensional Nussult correlations can be modeled interactively. Other advanced features include fluid flow, orthotropic materials, laminated plate elements for modeling composites, and radiation (specular or diffuse). FEMAP interfaces to all popular FEA structural codes and CAD systems. Support for radiation and orbital heating using TRASYS, NEVADA and THERMICA is also integrated into this environment.

This paper discusses the interfacing of the SINDA/G thermal analyzer with CAD systems to facilitate the creation of thermal models directly from the engineering design database. Both advantages and disadvantages of using CAD databases for thermal models are discussed. The types of problems that are more suited to this method are presented. Methods for converting the solids CAD geometry into SINDA nodes and conductors are also discussed.

The thermal design of a spacecraft is a time consuming and tedious process. As more graphical tools are becoming available, this process is becoming more efficient, and changes to the thermal design are more quickly implemented. The thermal engineer is required to master several software packages, such as a graphical model builder, thermal radiation and orbital heating program and a thermal analyzer. This paper discusses the THERMICA-SINDA/G software system, where the entire spacecraft thermal design process in integrated in one interactive graphical environment.

This paper discusses the use of graphical modelers for spacecraft thermal design. The advantages and disadvantages of using graphical modelers are presented. Working in the PC environment with low cost PC-based tools is compared to the workstation environment with more expensive workstation workstation-based products. The benefits of using CAD data for thermal models is discussed. Techniques for linking the temperatures from a thermal model to a structural model are presented.

The steady state and transient methods used in SINDA/G®[1] are discussed in this paper. The basic finite difference method is explained and derived from the heat equation. Explanations of the various control constants and rule of thumb settings are presented. Various numerical errors such as truncation, discretization and round-off are discussed. A speed comparison of the routines is presented in the form of bar charts. Finally, guidelines are presented for selecting a routine for a particular type of problem.