[Click for the bga-9.fe datafile in a second window.]
This model lets the upper chip move both vertically and laterally in
response to imposed loads.
Notable features:
The lateral parameter "offset" is converted to an optimizing
parameter the same way "height" was in bga-5.fe. A parameter
"lateral_load" is introduced, and used in the potential energy
quantity "pad_energy".
Because the upper pad is now implemented with boundaries, the upper
pad vertices move in unison when "offset" is changed during optimization.
The datafile is set up with no lateral load, but an initial lateral
offset, so you can watch "offset" optimize back to 0.
Even with no lateral load, the "offset" may not converge to exactly
zero because of asymmetries in the triangulation induced at non-zero
offset.