GRID: A FORTRAN Program for Using a Digitizing Table to Enter a Finite Element GRID.

An important initial step in any finite element analysis is the generation of the finite element grid, which is a list of nodes and their co-ordinates, and a list of finite elements,i.e., how the nodes are grouped together. The quickest and most reliable method to generate a finite element grid is automatically with a computer, but it is not economical to do so unless the same genre of problem is to be analysed many times. If the grid is not generated automatically, a graph of the grid must be drawn, and later entered into the computer by some means. Typographical entry of the data is time consuming and prone to error, so we have written a FORTRAN computer program, 'GRID', which uses a digitizing table to greatly speed up data entry compared with typographical entry. This report describes GRID, and provides an example of how GRID is used. GRID has been written specifically for the two-dimensional finite element program MAVART, but most of its subroutines are either of general applicability, or could be readily modified to meet the requirements of other finite element programs. The first section defines the task for which GRID was written. Subsequent sections describe the organisation of GRID, the initialisation procedure, and the layout of the switch box, and step-by-step instructions on how to digitize the small grid shown in Section 2.