Meshing

I would like to have a finer (or coarser) Finite Element Mesh. How can I do this?

To do this you will need to manually edit the iMesh file you are working on. But this is not difficult. Just to be sure, though, save your work before staring.

Press the button to show the iMesh data. Find the *MESH keyword. The fourth (and currently last item on the list is the maximum size for all elements relative to the diagonal of a rectangle containing your structure. The default value is 0.1, which means that the largest element edge is at most one tenth of the diagonal of the rectangle. If you want to have more element, make this value smaller, but be careful, as the number of elements varies with the invert of the square of that value! This means that if you set this value to 0.05 instead of 0.1 (two times smaller), you should approximately get four times the previous number of elements. Typical values for a fine mesh are around 0.03.

You can find more detail on the *MESH option in the description of the iMesh input file

How can I use additional nodes and polylines to locally refine my FE mesh ?

The iMesh applet was initially based on the premise that the Finite Element Mesh needs to respect all geometrical constraints specified by the user: wherever the user specifies the location of a node, there will be a node. Wherever the user specifies that there is a line (a polyline) separating two areas of the mesh, the edges of the elements are not allowed to cross that line, and element boundaries follow the line.

These properties can be used to concentrate the Finite Element Mesh in areas of interest, or where stress concentrations are largest. Polylines do not exist in reality. Their sole purpose is to force the FE Mesh to follow their boundaries.

How can I use iMesh to generate a Finite Element mesh for another program ?

At the present time, iMesh can generate input files for the following programs/applets: iConc, iOpt and ANSYS. The selection of the program for which the output will be given must be made before starting the applet by selecting it from the list of FE Programs accessible below the applet. Once the mesh is displayed, the input file for the program can be obtained by Holding down the Shift key and pressing the input file button. Selecting the whole contents of the input file can be performed by pressing Ctrl+A, copying it to the clipboard by pressing Ctrl+C. You can then save it to a normal text file (for instance using the Notepad program on a Windows PC).