GiD forum

Hello,

I have a small doubt about GiD.

When I'm modelling a surface (for a shell calculation, e.g.) and I use automatic generation of NURBS with 4 surrounding lines, the direction of the normal is chosen by the program. The problem is that I (we all, I hope) have to be very carefull in order to apply the loads correctly, so that they are in the correct direction (for example, in CALSEF). So, is there a simple way to swap the normal orientation?.

I have realized that this happens always when a part of the model has been generated by mirroring another part of it.


Thanks in advance,


Jesús Torrecilla Pinero

Escuela Politécnica
Universidad de Extremadura



Cáceres
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If the surface is in the XY plane, GiD automatically try to orient the normal pointing to positive Z axis.

If the surfaces are in 3D, the user can manually swap normals:
Utilities-DrawNormals-Surfaces
select the surfaces to draw/modify the normals
then click the righ mouse button, and select in contextual menu (or in the right menu buttons) another option:
Options are:
- Swap some: changes the sense of the normals of the surfaces after selecting them again.
- All swaped: changes the sense of all selected surfaces, asking for confirmation for the change.
- Swap group: changes normals of all selected surfaces or elements so as all of them have its normal to the same sense that adjacent entities. This sense is arbitrary but common to all adjacent entities.
- Sel by normal: user is prompt to enter a vector and selection is reduced to entities that have their normal in the same sense (dot product positive) as the given normal.
- Color: With this option set, all surfaces are draw with filled color.Their front side will be drawn with their regular color, and their back face with yellow.

Note:
The right menu buttons are hidden by default, see utilities-graphical-toolbars to visualize it.

Best regards
----- Original Message -----
From: Jesús Torrecilla
To: gidlist at gatxan.cimne.upc.es
Sent: Sunday, October 07, 2001 6:42 PM
Subject: [ GiDlist ] About normals


Hello,

I have a small doubt about GiD.

When I'm modelling a surface (for a shell calculation, e.g.) and I use automatic generation of NURBS with 4 surrounding lines, the direction of the normal is chosen by the program. The problem is that I (we all, I hope) have to be very carefull in order to apply the loads correctly, so that they are in the correct direction (for example, in CALSEF). So, is there a simple way to swap the normal orientation?.

I have realized that this happens always when a part of the model has been generated by mirroring another part of it.


Thanks in advance,


Jesús Torrecilla Pinero

Escuela Politécnica
Universidad de Extremadura



Cáceres
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