
                             SLFFEA 1.1 Plate README

                    Copyright (C) 1999 San Le

                    email:     slffea@yahoo.com
                    homepage:  http://www.geocities.com/Athens/2099/slffea.html


The patch test is divided into one for angles and one for displacement.  The reason
I think this is necessary is because of the non-linear relation between the 
displacements and the angles in the shape functions.  The element passes if the test
is divided in this way.

The angles phi x and phi y for the rotation are based on the right hand rule. 
Traditionally in plate theory, programs switch these angles.  I maintain the right
hand rule so as to keep the plate consistent with the shell. 

It is interesting to note that when you calculate stresses based on node points
rather than gauss points, the shear terms for some problems are qualitatively
correct for XX, YY, XY, I, and II but for ZX and YZ, they are very different.  Node
stress and strain ZX and YZ are orders of magnitude larger than when
under integration is used.  This is expected, since as you know, the purpose
of under integrating is to prevent shear locking.

