Overview > Finite Element Anaylsis and VisualFEA > Procedure of finite element analysis using VisualFEA

 

Procedure of finite element analysis using VisualFEA

The whole procedure of finite element analysis can be processed consecutively by a single executable module of VisualFEA. However, there is an alternative to split the procedure into a few stages and process each stage separately using different programs, especially employing external solver for main computation of the analysis.

> Stages of finite element analysis

The general procedure of finite element analysis can be split largely into 3 stages: preprocessing for preparation of modeling data, processing for assembly and solution of the equations, and postprocessing for visualization of analysis results.   

  Preprocessing: The stage of preparing input data for finite element analysis is called preprocessing.  The geometry of the finite element model is defined in this stage. The attributes and the various conditions are also applied to the model.
   

- definition of outlines and surface primitives

- division of the outlines to adjust the density of the mode

- finite element mesh generation

- assignment of element properties .

- assignment of boundary conditions.

- assignment of load conditions (only for structural analysis).

- node number or element number optimization.
  Processing: This is the kernel of finite element analysis. The finite element equations are assembled and solved at this stages, and thus, the analysis results are obtained. This computational procedure is automatically handled by the computer, and requires user interactions. The computation is carried out in the following sequence.
   

- computation of element stiffness matrix and equivalent nodal forces

- assembly of system equations - solution of the assembled equations

- recovery and smoothing of secondary variables   Postprocessing:

  Postprocessing is the stage visualizing graphically the analysis results and presenting them in more understandable forms.
   

- additional processing or transformation of analysis results   
- visualization of analysis results - handling of various output
- handing of various output

Some stages and procedures may be added or dropped depending on the analysis subject and the project contents.

> Finite element analysis using VisualFEA

Finite element analysis systems are generally composed of separate programs for each of the above 3 stages, and they are called preprocessor, solver and postprocessor respectively. On the other hand, VisualFEA has all the components integrated in one executable program. Thus, the whole procedure of finite element analysis can be completed by a single execution of VisualFEA. It is not necessary to pass the data from one program to another. There is only one data file for a project. All the modeling and analysis data are stored to and retrieved from the file. Once the file is opened, all data related with the finite element analysis are available for internal processing.

In some cases, the stages are not clearly separated, but intermixed with each other. It is possible to go back and forth freely between two different stages. In frame analysis, for example, the computed results are displayed graphically right after its geometry or attribute data are altered. In such cases, users can hardly distinguish the stages.

The software and data constructions are compared between VisualFEA and other programs. VisualFEA has a monolithic construction for both software and data, while most of other programs have complex constructions with multiple programs and a number of data files. Such a simple construction makes usage of VisualFEA simple and efficient.

< Comparison of software and data construction >

> Mixed use of VisualFEA and external solvers

Although the entire procedure of finite element analysis can be completed by a single execution of VisualFEA as described above, there is an alternative procedure in which an external solver is used together with VisualFEA . VisualFEA has powerful pre- and postprocessing capability, but can handle only relatively limited types of analysis. Therefore, it is sometimes desirable to accomplish pre- and postprocessing using VisualFEA, but adopt an external solver for analysis. In this case, input data for the analysis is created by VisualFEA, and supplied to the external solver, and the results computed by the solver are again retrieved to VisualFEA for graphically visualization. If existing third party software is used, an additional program for data interface between VisualFEA and the solver may be necessary. In case the solver is developed by the user, the computed results may be written directly in the VisualFEA file, so that neither extra files nor interface data files are necessary. The data interface with external solvers is described in detail in Chapter 10.