Warpage
The main purpose of the warpage evaluation is to compute how much an originally flat surface deviates from being planar after deformation. It is, however, possible to use the feature also for surfaces with an arbitrary shape. The process can seen as two steps:
•
First a rigid body rotation of the surface is computed as a best fit in a least squares sense.
•
From that rotated average surface, the deformation in the normal direction is computed.
The original (material frame coordinates of the surface (which can consist of several boundaries) are given as
X
. After deformation, corresponding points are located at
x
, where
x
=
X
+
u
.
The total displacement
u
is decomposed into an average part, and a warping part, so that
