Nastran composites FEA 1

[sccorpioh1]

Does anyone know how to detect or display which elements are missing an orientation in Nastran 9. I use Femap as the modeler and before Femap calls Nastran I get an error that says: "18 laminate elements were written with default orientation. Usualy laminates require a specific orientation". My model is very large and it would take me a very long time to find these elements. I called Nastran support but they could not help me. After i click ok on the error message, the program keeps running and i get answers, which seem right. There are no warnings or listing on the elements that have been given a default orientation. Thanks for your help!

 

[dmacx]

The 18 elements FEMAP is complaining about have no material orientation defined. I assume you have defined the orientation for the other elements in your model and that you know how to do this. When you export the model all you need to do is look at the Bulk Data file and look for CQUAD4 or CTRIA3. Then look to the right in field 8 for CQUAD4 or field 7 for CTRIA3 for a number. If it is blank then no orientation was specified or the orientation is zero. Orientation is with respect to the node 1-2 line of the element. FEMAP always uses an angle when it does specify but sometimes zero is left blank as the default. This will at least help you find the which ones are suspect.

Field 2 3 4 5 6 7 8
CQUAD4 1 10 16 4 5 17 45.
CQUAD4 2 10 4 10 11 5

Orientation angle ^^^^

 

[dmacx]

Sccorpioh1,

What did the Nastran support people tell you to try? Did my suggestion help?

 

[sccorpioh1]

Thanks dmacx. The Nastran support team told me the same thing. I tried finding the elemets. I imported the bulk data to excel and started looking. After looking through
about 15000 elements and finding about 100 elements with
no number in those spots, i gave up. I still had 25000 elements to go and had found 100 elements supposedly with
no orientation, i figured it wasn't working. I'm gonna split the model into several parts, and reapply orientation
according the the lay-up of each section. Thanks.

 

[GBor]

When you imported into Excel, you should have been able to use a space delimited file import and set it up so that the fields end up in different columns. Then you could filter on those columns when they have nothing in them. That should narrow it down in minutes instead of hours.

 

[dmacx]

Excellent idea Garland. Sorting would also work. Once you have the ids you can see what areas are missing orientation. The only problem is that a blank could be a zero that was specified so it does not necessarily mean a problem. It would be nice if FEMAP listed the ids from the start since it knows which elements there was no orientation specified for. Good luck!

 

[sccorpioh1]

Here is an API that will create a group with the laminate elements with no orientation. The Nastran team send me this. By the way, when i said they could not help me, i meant, at that instant, and not that they were not capable.
Sorry for the missleading coment Nastran support team. You guys rock!
To run this, you need to have the API toolbar active (Tools>API Programming). You can just delete the default entry that is in there and copy and paste what is below into the window.


Sub Main

Dim App As femap.model

Set App = GetObject(,"femap.model")

Dim s As femap.Set

Set s = App.feSet

Dim g As femap.Group

Set g = App.feGroup

Dim e As femap.Elem

Set e = App.feElem

While (e.Next())

If (e.type = FET_L_LAMINATE_PLATE ) Or (e.type = FET_P_LAMINATE_PLATE ) Then

If ( Not e.MaterialAngleFlag ) Then

s.Add(e.ID)

End If

End If

Wend

g.title = "Lam with No Orient"

g.SetAdd(FT_ELEM, s.ID)

g.Put(g.NextEmptyID)

End Sub



You can click on the “play” button to run the script. At the end you should have a new group with all the laminate elements included.
Then, all you have to is list the elements without orientation.