XANSYS Message: 37408 [Go back to message list]
[bookmark on del.icio.us]
No rating yet
Rate item:

Subject: Substructuring - problem in scaling of a load vector
Author: Nagendra Singh
Date: 2002-05-08 20:47:00

Hi All,

I am trying to use the substructuring feature of ANSYS in one the
electronic package. I am subjecting the package to a thermal cycle of
0C to 100C (10min ramp/5min dwell).

I used the linear material properties for die, overmold and die
attach and made them as one superelement in the generation pass. I
made two load vectors - 1) contains all the symmetry constraints
2) 1 degree decrease in temp (373 to 372)

Now, in the use pass I couldnt figure out how to scale the body force
(temperature)on superelement in between the substeps during the ramp,
for instance I am using the load file provided by Steve Groothuis

*do,cycle,1,ncycle
! ---- RAMP LOW (LOAD STEPS 1,5,9,...) ----
autots,off ! turn off auto time stepping
nsubst,rampstep ! set substeps for this load step
bf,all,temp,lowtemp ! apply uniform temperature to all nodes
kbc,0 ! linearly ramp load temperatures
time,(cycle-1)*tcycle+lowramp ! set time at end of load step
solve ! solve load step

! ---- DWELL LOW (LOAD STEPS 2,6,10,...) ----
autots,on ! turn on auto time stepping
nsubst,10,100,1 ! set the size of first time step
bf,all,temp,lowtemp ! apply uniform temperature to all nodes
kbc,1 ! use applied load temperature for all substeps
time,(cycle-1)*tcycle+(lowramp+lowdwel) ! set time at end of load step
solve ! solve load step

I guess, this scaling should be easily done during dwell by simply
using

BFE, all,2,selv,,100

Where,
a) `all' is the selected superelement
b)`2' is the second load vector as defined above
c)100 is the scale factor used for the dwell at temperature 273K

This is what I have figured out by reading the help on Substructuring
topic. So I might have used redundant steps in it like I doubt if we
really require two load vectors. So, I would highly appreciate any
modification/suggestion on this.

Thanks and regards,
Narendra Singh
Grad Student
SUNY Binghamton

Posts possibly associated with message #37408AuthorDateScore
37408Substructuring - problem in scaling of a load vectorNagendra Singh2002/05/08 
37439Re: Substructuring - problem in scaling of a load vectorNick nick@2002/05/09 
37445Re: Substructuring - problem in scaling of a load vectorNagendra Singh2002/05/090