Normal modes analysis of a two plies plate

[Dan90]

Hi to everyone,

I am completely new to the use of FEMAP and, as in the subject, I am trying to perform a modal analysis of a two plies plate but I am having two fatal errors from NX nastran.

In particular, the setup of the analysis I have setted is the following:

1) To import the .IGS file of the plate

2) To create the materials of the two layers

3) To create one layups with the two materials of point 2)

4) To define property (solid laminate) for the model

5) To mesh the geometry, recalling the property of point 4)

When I launch the analysis the NX nastran returns me two fatal errors:

**USER FATAL MESSAGE 6440 (MDG2EC)
ELEMENT 357 REFERS TO AN INVALID PROPERTY ENTRY.
USER ACTION: SPECIFY APPROPRIATE PROPERTY ENTRY.
**USER FATAL MESSAGE 6440 (MODGM2)
ELEMENT 357 REFERS TO AN INVALID PROPERTY ENTRY.
USER ACTION: SPECIFY APPROPRIATE PROPERTY ENTRY.
FATAL ERROR
***END OF JOB***

I do not understand where is the problem.
Could anyone help me?

Thanks.

 

[jbrackin]

If you are modeling a plate, then I would suggest using shell/plate elements. If you choose this method, then create an isotropic or 2D orthotropic material, then create your layup and then a laminate shell property.

If you decide you want to use a solid laminate element, you must use isotropic or 3D anisotropic material to create your layup and then choose a solid laminate element property.

 

[Dan90]

Hi jbrackin and thank you for the quick answer.

If I use your first suggestion, creating a rectangular surface in FEMAP environment (geometry-->surface-->corners), then the analysis is executed but this error message appears " Laminate Elements were written with default orientations. Usually laminates require a specified orientation".

On the contrary, if I want to follow the second option, it still does not work.
After I have imported a 3D rectangular plate, once I have created two isotropic materials for the layup and a solid laminate element as property, how should I correctly create the mesh for the entire geometry?

 

[jbrackin]

I would advise using the first approach for modeling plate structure.
For laminate elements, you need to define a material direction,even if you are using an isotropic material. Go to the Modify/Update Elements/Material Orientation and set for all elements that use laminate property.

 

[BlasMolero]

Dear Dan,
Here you are a tutorial explaining step-by-step how to create a 2-D composite model in FEMAP with orthotropic material properties:

http://www.iberisa.com/soporte/femap/composites/nafems_benchmark_composite_test_r0031_3.htm

You can learn how to define the material orientation:

And postprocess results:

Best regards,
Blas.

~~~~~~~~~~~~~~~~~~~~~~
Blas Molero Hidalgo
Ingeniero Industrial
Director

IBERISA
48004 BILBAO (SPAIN)
WEB:

http://www.iberisa.com

Blog de FEMAP & NX Nastran:

http://iberisa.wordpress.com/

 

[Dan90]

Thank both of you for the precious suggestions!
I will let you know..

 

[Dan90]

My model worked!
Thank you BlasMolero, your tutorial was very helpful!