Prepomax issue - "Missing section assignment at element...."

General Questions
1

Hello everyone, i am trying to simulate a wing with ribs inside, i am continuously facing this issue:

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image536×204 6.25 KB

Can someone please tell me how only only element can’t be assigned material? I am working with the orthotropic material for the wing surface with the keyword :

*MATERIAL, NAME=composite
*ELASTIC, TYPE=ENGINEERING CONSTANTS
140000, 9000, 9000, 0.3, 0.3, 0.4, 5000, 5000
1500, 294
**
*ORIENTATION, NAME=OR1,SYSTEM=RECTANGULAR
1.0, 0.0, 0.0, 1.0, 0.0, 0.0
*ORIENTATION, NAME=OR2,SYSTEM=RECTANGULAR
1.0, 0.0, 0.0, 0.0, 1.0, 0.0
*ORIENTATION, NAME=OR3,SYSTEM=RECTANGULAR
1.0, 0.0, 0.0, 1.0, 1.0, 0.0
*ORIENTATION, NAME=OR4,SYSTEM=RECTANGULAR
1.0, 0.0, 0.0, -1.0, 1.0, 0.0
**
*SHELL SECTION, , COMPOSITE, Elset=Element_Set-1
4, , composite, OR1
4, , composite, OR2
4, , composite, OR3
4, , composite, OR4
4, , composite, OR4
4, , composite, OR3
4, , composite, OR2
4, , composite, OR1

2

This orientation is invalid.

*ORIENTATION, NAME=OR1,SYSTEM=RECTANGULAR
1.0, 0.0, 0.0, 1.0, 0.0, 0.0

3

You have to assign it to a set. Either via mesh-based selection in PrePoMax or using keywords:

*ELSET, ELSET=elset_name

element_number

Regarding warnings about missing sectioj assignments, keep in mind that PrePoMax will issue them if you only define section in Keyword Editor. You can skip such warnings or assign dummy non-composite sections in PrePoMax and then add custom section keywords in the Keyword Editor after those - they will overwrite the dummy ones: