3D geometry ID modification

Coreform Cubit Creation and Modification
#1

Hi all,

I am currently working on creating a 3D structure. I have choosen the method “bounding surfaces” because I need to know the IDs of all surfaces to create nodesets/elementsets later on. This works fine

But creating a volume by surfaces modifies the IDs of the curves, which I would like to know as well because I want to define strict curve interval definitions.

Why does cubit change the ids? Can I force cubit to keep all the ids?

Or do you have to switch to python programming interface?

Many thanks!
Oberjonny

#2

What type of behavior are you expecting when two curves get combined into one with a ‘stitch’ or a ‘bounding surfaces’ method? Are you hoping that at least one curve survives? Although IDs will not survive, if the curves are named, one of the names will survive. Try this:

reset
brick x 1
set default names on
surface 1 6 copy
set default names off
delete volume 1
list curve 13 #has name cur13
list curve 21 #has name cur21
stitch volume all
list curve 21 #the name cur13 has survived

#3

Many thanks for your fast replay! I am still learning how cubit works!

I have made a small cube example in the way I would like to build up my model. In the end I would like to have polygons. I changed the name of the curves of the front surface, but cubit always changes the name dd to dd@A. aa, bb and cc stay the same. How can I avoid this? Here is the model:

reset

create vertex 0 0 0
create vertex 0 0 1
create vertex 0 1 1
create vertex 0 1 0

create vertex 1 0 0
create vertex 1 0 1
create vertex 1 1 1
create vertex 1 1 0

create curve vertex 1 2
curve 1 name ‘aa’
create curve vertex 2 3
curve 2 name ‘bb’
create curve vertex 3 4
curve 3 name ‘cc’
create curve vertex 4 1
curve 4 name ‘dd’

create curve vertex 5 6
#curve 5 name ‘ee’
create curve vertex 6 7
#curve 6 name ‘ff’
create curve vertex 7 8
#curve 7 name ‘gg’
create curve vertex 8 5
#curve 8 name ‘hh’

create curve vertex 1 5
curve 9 name ‘ii’
create curve vertex 2 6
curve 10 name ‘jj’
create curve vertex 3 7
curve 11 name ‘kk’
create curve vertex 4 8
curve 12 name ‘ll’

create surface curve 1 2 3 4
create surface curve 5 6 7 8

create surface curve 1 9 5 10
create surface curve 2 10 6 11
create surface curve 3 11 7 12
create surface curve 4 12 8 9

create volume surface 1 2 3 4 5 6 heal

I a second example of an polygon the create volume surface does not work anyway. WHy does only the stitchwork? In the end I would like to identify a certain number of curves,but I do not know how to do that in a scripted way? Here is the second model:

reset

vertices

create vertex -0.011647 0.05 0
create vertex -0.01687 0.049736 0
create vertex -0.028692 0.026123 0
create vertex -0.028513 0.025748 0
create vertex 0.002763 0.02566 0
create vertex 0.014113 0.05 0

create vertex -0.011647 0.05 0.001
create vertex -0.01687 0.049736 0.001
create vertex -0.028692 0.026123 0.001
create vertex -0.028513 0.025748 0.001
create vertex 0.002763 0.02566 0.001
create vertex 0.014113 0.05 0.001

lines

create curve vertex 1 2
curve 1 name ‘aa’
create curve vertex 2 3
curve 2 name ‘bb’
create curve vertex 3 4
curve 3 name ‘cc’
create curve vertex 4 5
curve 4 name ‘dd’
create curve vertex 5 6
curve 5 name ‘ee’
create curve vertex 6 1
curve 6 name ‘ff’

create curve vertex 7 8
create curve vertex 8 9
create curve vertex 9 10
create curve vertex 10 11
create curve vertex 11 12
create curve vertex 12 7

create curve vertex 1 7
create curve vertex 2 8
create curve vertex 3 9
create curve vertex 4 10
create curve vertex 5 11
create curve vertex 6 12

surfaces

create surface curve 1 2 3 4 5 6
create surface curve 7 8 9 10 11 12
create surface curve 1 13 7 14
create surface curve 2 14 8 15
create surface curve 3 15 9 16
create surface curve 4 16 10 17
create surface curve 5 17 11 18
create surface curve 6 18 12 13

volumes

stitch body 1 2 3 4 5 6 7 8
#create volume surface 1 2 3 4 5 6 7 8

Many thanks for your answer!

Best regards
Philipp

#4

Trelis will rename an entity using @A when creating a duplicate of an entity. For example, a surface called “aa” will be split into “aa” and “aa@A” to let you know that the new surface comes from “aa”. See below.

reset
create surface rectangle width 10 zplane
surf 1 name “aa”
split surface 1 through vertex 1

The result is two surfaces, “aa” and “aa@A”.