Create Surface from Vertex

Coreform Cubit Geometry
#1

Hello,

I would like to know what the criterion of cubit/trelis for the creation of surfaces from vertices is. The error message I am referring to is:

ERROR: ACIS API error number 90015
ACIS API message = A face with NULL geometry created
WARNING: >>>WARNING:Surface creation was unsuccessful.<<<

the surface which i like to create is created by vertices with the following command:

reset
create vertex 1.1874 1.37831 1.00748
create vertex 1.01731 1.12903 1.55853
create vertex 0.39183 0.34683 1.30847
create vertex 0.33698 0.29993 0.91935
create vertex 0.6473 0.69346 0.952
create surface vertex 1 2 3 4 5

where vertex 5 is a colinear vertex between vertex 1 and vertex 4. I need this coplanar vertex because I lateron would like to create volumes with different (subdivided) surfaces. Adjacent faces to subdivided faces will have one colinear vertice within the face definition. If i do not use this point the surface gets created (create surface vertex 1 2 3 4). If I include this point the above mentioned error message occurs. I am wondering what this error message states and why exactly it appears?

In general cubit seems to be very flexible during the creation of surfaces but somehow it seems to have problems with some (nearly!?) colinear points.
I am using cubit 13.2.

Best wishes
Martin

#2

Martin,

Thanks for the post. There is a problem with the ACIS geometry kernel when vertex 5 is colinear with vertex 1 and 4. I’ve reported it.

Here is a way to get what you want:

reset
create vertex 1.1874 1.37831 1.00748
create vertex 1.01731 1.12903 1.55853
create vertex 0.39183 0.34683 1.30847
create vertex 0.33698 0.29993 0.91935
create surface vertex 1 2 3 4
split curve 2 0.6473 0.69346 0.952

The result is two curves with vertex 5 at 0.6473 0.69346 0.952.

#3

Hello,
thank you very much for your fast reply. It really helped me alot! I am using a slightly different format now as in your format the cutting point is not the cutting point I desired. From the manual it seems that for your definition the point is defined relative to the curve points.

But this is working fine for me now:

reset
create vertex 1.1874 1.37831 1.00748
create vertex 1.01731 1.12903 1.55853
create vertex 0.43329 0.39869 1.32505
create vertex 0.35209 0.3191 0.92092
create vertex 0.64893 0.6955 0.95168
create surface vertex 1 2 3 4 noheal
split curve 4 at vertex 5

Best wishes
Martin