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Thermal analysis is typically performed using a point design approach, where a single model is analyzed one analysis case at a time. Changes to the system design are analyzed by updating the thermal radiation and conduction models by hand, which can become a bottleneck when attempting to adopt a concurrent engineering approach. This paper presents the parametric modeling features that have been added to Thermal Desktop™ to support concurrent engineering. The thermal model may now be characterized by a set of design variables that are easily modified to reflect system level design changes. Geometric features, optical and material properties, and orbital elements may all be specified using user-defined variables and expressions. Furthermore, these variables may be automatically modified by Thermal Desktop's optimization capabilities in order to satisfy user-defined design goals, or for correlating thermal models to test data.

The trend towards concurrent engineering requires that designers and engineers of all disciplines share a common engineering database. Incorporation of existing radiation solvers into the CAD environment has had limited success, chiefly due to the limited set of surface types that can be analyzed and the incompatibility with FEM generated meshes. This paper describes RadCAD™, a new radiation analyzer integrated within the CAD environment. In addition to the basic set of conic surfaces, RadCAD also analyzes arbitrary free form surfaces and directly supports FEM meshes. The motivation, design approach, and algorithmic improvements for RadCAD are presented.

Despite recent advances in computer aided design (CAD) based tools, spacecraft thermal analysis remains outside the realm of finite element method (FEM) based analysis. The primary complaints against FEM often cited are: 1. FEM is not based on physical principles. 2. FEM codes do not provide procedural modeling for heaters, heat pipes, or other abstract thermal control components. 3. Inadequate radiation analysis capabilities. 4. FEM codes generate inappropriately large thermal models. However, a failure on the part of existing FEM based codes does not invalidate the advantages of the Finite Element Method. Properly implemented, FEM based systems can have significant advantages. A simple first law interpretation of FEM is presented, and shows that finite difference (FD) and FEM meshes may co-exist in the same thermal model, and solved using traditional analyzers such as SINDA/FLUINT.