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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.