[Click for the tomb-B.fe datafile in a second window.]
This datafile adds a solder blob to the chip-pad model of tomb-A.fe.
|Starting geometry.||Labelling of the vertices and edges of the liquid solder.|
|Evolved shape with 8236 facets.|
set facet tension 300 where not fixed".
readsection of the datafile starts off with
hessiancommand considers only motion perpendicular to the surface, which makes for much easier convergence. It does not converge to the absolutely best vertex positions for the triangulation, so
gcommands can still decrease energy, since
gis not restricted to normal motions. The difference in energy, though, is probably much less than the imprecision due to the finite triangulation.
target_toleranceis set to 1e-14. This is the criterion for convergence to the target volume of the solder. The default value of 1e-4 is much too small, since the volume is 2e-8. This is one of the adjustments that has to be made for doing a physically small model.
gogofor a typical short evolution. It starts out by refining some longer edges of the solder; the cutoff length of .0048 was chosen to get the desired edges refined. After that, it's just a little evolution at each refinement, just to set up the
hessiancommands for final convergence.
gogocauses a conversion from the Evolver's original style of energy calculation to the newer, more systematic, named methods and named quantities style. Many energies have Hessian calculations only in named quantities mode, in this case gravitational energy. This is not the default mode yet, since it is a little slower for regular iteration. (The automatic conversion is new in version 2.11; it may be turned off by starting Evolver with the -a- option.)
gofarcommand evolves to a higher refinement, which was used to make the evolved image on this page.
change_z0for smoothly changing the position of the chip. Simply changing the position parameters and relying on the constraints can do some ugly things to vertices in the middle of chip faces. Also, these commands linearly interpolate the motion of the liquid solder surface between the pad and the chip, giving smoother motions over large distances.
calc_zfto calculate the forces exerted on the chip by the surface tension of the solder. The method is to use the principle of virtual work, moving the chip a bit (using the change position commands) and finding the energy difference. Central differences are used for greater accuracy.
scriptcommand defined that evolves and prints energies and z forces to a file called "tomb-b.out".
|Refinement||Solder facets||Energy||Z force|