Changing select tolerance: ASEL

[laserablaatio]

I'm trying to use the ASEL command to select a layer in my model and I noticed that ASEL tolerance does not work very intuitively in my opinion:
Two examples
1)ASEL,S,LOC,Z,3015 -> tolerance = 15.075
2)ASEL,S,LOC,Z,3014.9,3015.1 -> tolerance = 0.2E-8
This goes as stated in the documentation.

I hunted down the reason for the weird behaviour of my model for couple of hours... Is there any means to control the tolerance with some control parameter, so that command 1) could be used "safely"?
Of course, I could use a command like
ALPHA = 0.1
ASEL, S, LOC, Z, 3015 - ALPHA, 3015 + ALPHA
but using command 1) would produce much cleaner code.

I'm using Ansys 9.2.

Thanks for your answers!

 

[Stringmaker]

There are commands within Ansys for layer selection. I do not have the Ansys documentation handy due to my being out of the office but have you looked at the LAYER, SHELL, and ESEL,,LAYER commands?

I don't have much experience with layered elements to be honest but what if you could have something like this in your code to select the layer of interest:

ASEL !select the areas containing elements
ESLA,S
ESEL,R,LAYER !select layer in subset of elements of interest

Just a thought. I've used the LAYER and SHELL commands only for postprocessing so I'm not sure how useful they'd be outside of /POST1. What are you trying to do exactly once you select a certain layer?

-Brian

 

[laserablaatio]

Maybe I misused the term layer ... my intention is to select some areas which have a certain z-coordinate and which have been drawn perpendicular to the z-axis. After this selection the area is extruded with the VEXT command.

My problem was that the tolerance in the ASEL command was too big, and a nearby area having not the Z coordinate I wanted was selected too.

It just somehow nonpractical (and for me lead to a hard-to-find error in my scripts) that the tolerance in the ASEL command scales with the parameter Z_TO_BE_SELECTED
ASEL,S,LOC,Z,Z_TO_BE_SELECTED
-> tolerance = 0.005 x Z_TO_BE_SELECTED
In my previous example with numbers the result is:
ASEL,S,LOC,Z,3015 -> tolerance = 15.075

 

[cbrn]

Hi,
why not impose the tolerance inside the ASEL command? If I remember well, It would be something like
ASEL,s,loc,z,Z_START,Z_END,0.001
for example.
I'm not so sure because I very seldom have to cope with sel tol problems...

Regards

 

[meshparts]

Hi,

I would use the command

SELTOL, Toler

Regards,

Alex

 

[laserablaatio]

Thanks a lot, this was exactly the answer I was looking for.
SELTOL seems to be an undocumented feature (at least in
Ansys 9.2, the version I use).

I found it listed on the Ansys Undocumented Features at ansys.net:

http://ansys.net/ansys/?mycat=search&mytype=Undocu&mycategory=Selection