Finite element modeling models code, ANSYS

The Vessel System, including the support subsystem, is analyzed using the NSSS finite-element model and response spectra input generated by the plant seismic analysis discussed in Section 3.7.2. This three-dimensional finite-element model is based on the Vessel System arrangement and is shown in Figure 3.7-6. The analysis is performed using the ANSYS computer code and the analysis procedures discussed in Section 3.7.3.1.1. (Ref. 11)... 

Stress calculations are carried out by the finite element method. Here, the commercial finite method code ABAQUS (Hibbit, Karlsson, and Sorensen, Inc.) is used. Other codes such as MARC, ANSYS are also available. To calculate the stresses precisely, appropriate meshes and elements have to be used. 2D and shell meshes are not enough to figure out stress states of SOFC cells precisely, and thus 3D meshes is suitable for the stress calculation. Since the division of a model into individual tetrahedral sometimes faces difficulties of visualization and could easily lead to errors in numbering, eight-comered brick elements are convenient for the use. The element type used for the stress simulation here is three-dimensional solid elements of an 8-node linear brick. In the coupled calculation between the thermo-fluid calculation and the stress calculation a same mesh model have to be used. Consequently same discrete 3D meshes used for the thermo-fluid analysis are employed for the stress calculation. Using ABAQUS, the deformations and stresses in a material under a load are calculated. Besides this treatment, the initial and final conditions of models can be set as the boundary conditions and the structural change can thus be treated. 

The strength characteristics can be calculated with finite element methods (FEMs). Besides stress-strain analyses, thermodynamic and fluid dynamic tests can be carried out. Preprocessors enable automated net generation based on the initial geometric model. Most CAD systems have interfaces for common FEM programs (e.g., NASTRAN, ANSYS) or have their own equation solver for FEM tests. Based on the substantial data resulting from an FEM test, it is necessary for postprocessing of results. The results are then portrayed in deformation plots, color-coded presentations of the stress-strain process, or animations of the deformation. 

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