## F. Mesh Generation

Mesh generation can be carried out completely by the user.However, in most cases, the structure’s form enables the use of an automaticmesh generator, which creates node coordinates and element topologies. Thus,the user has only to define a gross division based on “super elements”, and toselect for each of them their automatic division into finite elements. Thecorresponding file, named *.mos and described in Section‎V.B, can easily be changed using the Modify button of the supervisor. The MOSAIQUE procedure automatically transforms the “super elements” into finiteelements used by ATILA. The resulting file is an .ati file.

The ATILA data file describes thetype of analysis, the node coordinates, the element topology, the physicalproperties of the materials and the geometrical properties of the elements, theloading and excitation data and the boundary conditions. Chapter ‎III describes the complete preparation of the data file and should be read carefully. Finally, when the automatic mesh generation code MOSAIQUE is used, the data entry file can largely be obtainedautomatically. It is possible to change data in the .ati file using the Modify button.

Checking the data file can be done with the Draw the mesh button. The generated mesh is shown directly onthe screen. Many commands are available under these three menus: File, Edit and Options.

The File menu commands are used to opena file, save the drawing or quit the program. The Edit menu contains several commands, as explained below.

The Axes command sets the view anglerespective to the mesh. The initial viewing direction shows the Oz axispointing towards the viewer, so that the surface of the screen or paper isparallel to the x0y plane. For a three-dimensional mesh, it is possible tochange Theta and Phi angles. Theta is the angle from the 0z axis to the viewpoint, while Phi is the angle from 0x axis to the projection of the view pointon the x0y plane.

Initially, a Simple mesh is presented. With Draw parameters you can select thedrawing or display method.

The Draw Parameters are:

- Simple mesh is used for an unexploded view of the mesh. The elements are shown with a full line. Nodes do not appear.
- Exploded mesh is used for an exploded view of the mesh without node numbering. The elements are shrunk by a small factor and shown with a fullline.
- Exploded mesh with node numbers is used for an exploded view of the mesh with node numbering. The elements are shrunk by a small factor andshown with a full line. Nodes are shown as small circles, with numbering closeto them.
- Exploded mesh with element numbers is used for an exploded view of the mesh with element numbering. The elements are shrunk by a small factorand shown with a full line. Nodes are shown as small circles. Element numbering appears near the element's center.
- Mesh with degrees of freedom is used for an unexploded view ofthe mesh, with degrees of freedom shown as small vectors. The elements areshown with a dashed line. On each node is shown a series of vectors, corresponding to the direction of active degrees of freedom. Displacements Ux, Uy and Uz are shown with a simple arrow. Rotations qx,qy and qz are shown with a double arrow. Pressures are shown like Ux. Potentials are shown like qx. Excitation currents are not shown.
- Dashed wire frame mesh with solid outline is used for anunexploded view of the mesh with dashed inside lines. The element vertices are shown with a full line if not connected to other elements; otherwise, theyare shown with a dashed line. Nodes do not appear.
- Together with the previous buttons, it is possible toselect the elements to draw, by entering the numbers ofthe first and last shown element (from and to boxes). When the all button is used, the whole structure is shown. The user may also restrict the display to a parallelepiped box whose limits are given in the Xmin, Xmax, Ymin, Ymax, Zmin and Zmax boxes.

It is possible to use a zoom by pressing shift-Z on the keyboard.

Redraw, copy and print are also commands available under the Edit menu. Thedrawing can be integrated in most Windows applications.

The Options command changes thelanguage (English or French).It defines the language used for the entry input and output. In France, thedefault language is French; in other countries, it is English.