[Click for the tomb-C.fe datafile in a second window.]
This model introduces partial wetting on the pad and chip bottom. That is, there are a non-zero contact angles. As a result, the corners of the pad are bared, as is some of the underside of the chip wetting area.
|Evolved surface, 9772 facets.|
|The solder surface by itself.|
A_padfor the pad and
A_z_minusfor the bottom of the chip, in degrees.
readsection of the datafile is defined to do this, for user convenience when changing the contact angles at runtime. The
updatecommand is then set to run when the file is loaded to set the initial tensions.
gogocommand illustrates a possible asymmetry in the evolution of a supposedly symmetric surface. In particular, the
uequiangulation command can destroy symmetry.
hessian_normalmode can have problems with vertices on constraints, as they can squirt sideways and make big spikes. A new feature in version 2.11 is the
hessian_slant_cutoffinternal variable. It's effect is that if the normal to the surface is at too great an angle from the permitted motion along constraints, the vertex is treated as fixed. The value is the cosine of the angle. The
hessian_slant_cutoffat .2 (by trial).
hessiancommand can have problems with one-sided constraints, as vertices bump into and off of the constraints. Here,
hessiandoes happen to work okay. If it doesn't, one can first
fixthe vertices that hit one-sided constraints.