Super element and Primitives are two unique methods developed by Network Analysis, Inc. When radiation codes (such as THERMICA, NEVADA, TRASYS or TSS) work with FEM modelers, two main problems with radiation analysis become apparent. (1) FEM modelers may create hundreds of thousands of elements in the model. This large amount is acceptable for structural analysis or for MSC Sinda heat conduction calculation, but it can be a disaster for radiation analysis. It will cause radiation analysis too slow, or even exceed the nodal limitation. (2) FEM elements only have flat small facets. The real curved surfaces (geometry parameters) are lost during the FEM data translation. A real curved surface will be represented by many small flat facets. This may cause unacceptable errors and too many nodes for radiation analysis. Sometimes the analysis of real curved surfaces is required for more accuracy, such as when performing thermal analysis on an optical paraboloid mirror.

The hundreds of thousands of elements in the FEM model are not required by radiation analysis. For example, a cylinder can be one node in a radiation model, but FEM modelers cannot use only one element to simulate the cylinder shape. FEM modelers may need 10 or 20 elements along the circular direction for a better simulation to a cylinder. That is to say, FEM modelers have to use 10 to 20 small flat facets to represent 1 true cylinder surface in radiation model. This causes simulation errors and more calculation time, and may even exceed the nodal limitation of radiation codes.

MSC Sinda has no problem solving hundreds of thousands of elements, while radiation codes such as THERMICA, NEVADA, TRASYS, TSS can solve only several thousand nodes. Therefore, we need a method that uses the big model (FEM model) for MSC Sinda calculation, and the much smaller model (radiation model) for radiation analysis. At the same time, we need a way to link the big FEM model and small radiation model. At Network Analysis, Inc., we developed the super element and primitive methods in MSC Sinda for Patran, thus solving the two main problems of radiation analysis.