Overview > Framework of VisualFEA > Preprocessing

 

Preprocessing

Preprocessing functions are to create, edit and check the modeling data necessary for finite element analysis. The data are constructed in a few steps: creation of boundary curves and surface primitives, mesh generation and data assignment. The preprocessing functions are sub-grouped based on these steps.

> Curve and surface primitive modeling

To construct the geometry data of finite element analysis model, curves and surface primitives must be created first. They are used as constraining objects for mesh generation. There are several types of curves and surface primitives as listed below. Each type is associated with an independent function activated by a tool command, and has a number of options which appears as items in the corresponding menu. 

  Straight line
  Circle/circular arc
  Ellipse/elliptic arc
  Parametric curve: cubic spline, B-spline, Bezier, polynomial
  Segmented curve
  Sphere
  Cylinder/cone/truncated cone
  Torus
  Parametric surface: plane, B-spline, Bezier surface

There are also functions related with devising curves which is necessary for mesh generation.

> Mesh generation

The functions of mesh generation are the most sophisticated, and the most important part of VisualFEA. Each of the mesh generation methods is associated with an independent menu command. The methods are classified into a few groups based on the type of user interaction and the type of generation algorithm:

  Automatic mesh generation
   

- Planar mesh by triangulation (triangular , quadrilateral , or mixture )
   

- Surface mesh by triangulation ( "  )
   

- Triangulation on surface primitives( " )
   

- Tetrahedronization of volume( 4 node or 10 node tetrahedron )
  Coordinate mappinga
   

- Surface mesh by 2 edge mapping (lofting)
   

- Surface mesh by 3 edge mapping (triangular mapping)
   

- Surface mesh by 4 edge mapping (transfinite mapping)
   

- Volume mesh by 9 edge mapping
   

- Volume mesh by 6 edge mapping
   

- Volume mesh by 12 edge mapping
  Sweeping 
   

- Extrusion
   

- Translation
   

- Revolution
   

- Twisting
  Mesh Editing
   

- Dragging nodet
   

- Remeshing
   

- Crack tip elemen

> Data Assignment

A finite element analysis model is completed by assigning necessary data to nodes and elements. There is an independent function to assign each type of data. The data can be assigned, removed, edited and checked interactively. There are also independent auxiliary functions related with data assignment.

  Boundary condition
   

- Fixity defined in local or global coordinates
   

- Initial displacement
   

- Spring defined in local or global coordinates
  Element property
   

- Material property
   

- Type definition (for mixed structures)
  Load condition
   

- Nodal, point, uniform, trapezoidal, parabolic, moment, body force , hydrostatic
   

- Thermal load, self-straining
   

- X, Y, Z axis direction, normal direction, tangential direction
   

- Load combinations
  Dynamic motion
   

- Displacement
   

- Velocity
   

- Acceleration
   

- Nodal dashpot
   

- Nodal mass
  Member joint
  Heat boundary condition
   

- Temperature
   

- Heat flux
   

- Heat source, sink
   

- Convection
  Seepage boundary condition
   

- Open head
   

- Confined head
   

- Flux
   

- Nodal source
   

- Initial water table

> Others

Various objects created in preprocessing stage can be manipulated by object operations as listed below. Node and element numbering can also be optimized to improve the computational efficiency of processing. The procedures can be done prior to processing. 

  Object operations
   

- Duplication
   

- Mirroring
   

- Rotation
   

- Scaling
   

- Projection
  Number optimization
   

- Node number optimization
   

- Element number optimization