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jan.patrick

Error 14 at a composite sandwich structure analysis

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Hello guys,

 

I'm currently trying to simulate a 3 point bending test to get the best material arrangement for high bending stiffness in a composite monocoque, while keeping the weight low.

 

The laminate i strive for is a sandwich structure with an aramide honeycomb core in the centre and three plies of different material on top and on the bottom. 

 

These are the steps I did so far:

 

1) I created a CAD model, imported it to HyperMesh, organized the componets (specimen, impactor, support) and meshed them with 2D elements.

 

2) I created the materials. MAT1 for the impactor and the support of the 3 point bending test, MAT8 for the different plies and MAT9ORT for the honeycomb core. 

 

3) After that I created the properties. PSHELL with an elementthickness of 2 for the impactor and support, PCOMPP for the plies and PSOLID with the honeycomb material for the core.  

 

4) Then I created the different plies. 6 with the MAT8 material for the top and bottom layers and 5 with the MAT9ORT material for the core to get a total of 5 elements over the thickness of the core. The material type for all plies is ORTHOTROPIC.

 

5.1) I created a laminate with the 5 core plies and then did a "shell to solid conversion" with this laminate. After that I got a new component with 5 elements over the thickness.

 

[5.2) In a second try I did the "shell to solid conversion" with the plies of the core which led to the same result as 5.1]

 

6) I assigned the PCOMPP property to the specimen elements, otherwise the laminate and layers weren't visible over 2D detailed element representation.

 

7) I updated the laminate with the other 6 plies.

 

8) Finally I created the load collectors and the load step, an output request for CSTRAIN and CSTRESS

 

9) I started OptiStruct to run the analysis.

 

But after a few seconds i got these errors: 

 

*** ERROR 14: Missing      MAT #    5 referenced by     PLY # 7,
    (existing MAT with this ID is of incorrect type).
 *** ERROR 14: Missing      MAT #    5 referenced by     PLY # 8,
    (existing MAT with this ID is of incorrect type).
 *** ERROR 14: Missing      MAT #    5 referenced by     PLY # 9,
    (existing MAT with this ID is of incorrect type).
 *** ERROR 14: Missing      MAT #    5 referenced by     PLY # 10,
    (existing MAT with this ID is of incorrect type).
 *** ERROR 14: Missing      MAT #    5 referenced by     PLY # 11,
    (existing MAT with this ID is of incorrect type).
 *** Errors with missing, incorrect or duplicate IDs found 5 times.
 
So when I got back to the model to check the properties, I wasn't sure if the PSOLID property and the MAT9ORT material are assigned to the plies in the laminate or to the new created component for the solids of the conversion. 
 
I want to get a laminate with from top to bottom: 3 layers of PCOMPP MAT8, the PSOLID MAT9ORT core and then 3 layers of PCOMPP MAT8 again. Is it even possible to creat such a laminate and if yes, in wich order should I assign the properties and creat the laminate?
Or are there other ways to simulate this kind of sandwich structure in HyperMesh and OptiStruct?
 
Here I uploaded the HM file so you can have a detailed look at my model:

 

I hope you get my problem and can help me fix it.

 

Thanks in advance!

 

 

 

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Guest

Hi Jan,


 


Sorry for a late reply.


 


So, you have a PLY card applied to solid elements. Instead, use PSOLID with MAT9ORT for solid elements.


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Hi Prakash,


 


when I change the Card Image of the plies from PLY to NONE, I get the ERROR "missing ply" and an other Card Image for the single plies is not available.


The only way I see to assign PSOLID with MAT9ORT to the solids I converted from the shell elements, is to assign the property to the automatically created component. But I am not able to put the SOLIDS into my Laminate.


 


Now how can I create an Laminate with plies and solids? 


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Hello Prakash, 


 


I have a similar problem so I hope posting here is ok. 


 


My model is very similar to the one uploaded here, I just haven't modelled the supports and the impactor explicitly. I applied the forces directly to the specimen. 


I would like to model the core as a solid, but I can't seem to find the option and I couldn't find any help on that online (after about 2 hours of searching the internet and the Hyperworks Documentation (!)). Could you (or anyone) help me with that?


I have modelled the core as isotropic material, not as a MAT9ORT because I don't have all the data. Can I convert the shell to a solid when using MAT1? 


And one more thing, you suggest having the shell plies in the laminate and the solid core out of the laminate. Could you elaborate on that, e.g. add some details?


Thank you very much!


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Hi Prakash Pagadala,

 

I can not open the file which you attached before. The interface shows the file is not backwardly compatible with the vision. My hypermesh is too old vision for this file?

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Hi Prakash,

 

when I simulate the 3 point bending test with the model I set up and the model I downloaded from your link, I have the problem that only the laminate on top and on the bottom are transmitting any stresses. If I check the element stresses for 2d and 3d the core is completely blue (0 MPa) and the displacement of the sandwichstructure is way too high.

Also if I try to edit the solids via solid edit I can not select the solids in the core as if there are no solids at all.

 

Do you know where the problem is and how I can transmit the stresses into the core?  

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Hi Jan,

 

What type of stresses are you looking at?

 

Composite stress is not available for solid elements.

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