XANSYS Message: 37439 [Go back to message list]
[bookmark on del.icio.us]
No rating yet
Rate item:

Subject: Re: Substructuring - problem in scaling of a load vector
Author: Nick nick@
Date: 2002-05-09 12:54:00

SFE,... ! Apply superelement load vector
--- ! Load step options
You have to use SFE with SELV.
Read the sample input for doing substructuring and SFE manual.
Steve's input files are not written for Substructuring analysis.

Hope this gives you a good starting point.
-n

-----Original Message-----
Sent: Wednesday, May 08, 2002 5:47 PM
To: xansys@yahoogroups.com

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 #37439AuthorDateScore
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