material orientation for honeycomb modelling with /PROP/TYPE6

Altair Forum User
Altair Forum User
Altair Employee
edited October 2020 in Community Q&A

Im trying to model a solid honeycomb core with MAT28 and PROP6. I'm using a local coordinate System (/SKEW/FIX with Ip=0) to define material orientation. I tried to Change the local coordinate System but the solver always refers to the global coordinate System. A change of the local coordinate System does not affect a change of the material orientation therefore i'm not able to define the material orientation with a local coordinate system.

Can anyone help me with this issue?

 

Best regards

 

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited January 2018

    Hi,

    Can you try assigning the orientation using the vector base node and vector end node option in /PROP/TYPE6 card?.

    If the issue persist please share the out files.

    <?xml version="1.0" encoding="UTF-8"?>hc.PNG

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited November 2020

    Hello George,

     

    Thanks for your reply.

    I've tried to assign the orientation using the vector base node and vector end node Option. In one case the local vector i defined corresponds to the global X axis and in the other case to the global Y axis. But the Problem still persists so i receive same results in both cases.

     

    Please find attached the .out files of both models

    Unable to find an attachment - read this blog

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited January 2018

    Hi,

    Can you please share your model file so that we can review and can update you.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited November 2020

    Hello George,

     

    please find attached the model files

     

     

     

    Unable to find an attachment - read this blog

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited January 2018

    Hi,

    Reviewed the orthotropic orientation of  your model in HyperCrash  and it seems that the skew is taken into account.

     

     

     

    <?xml version="1.0" encoding="UTF-8"?>Untitled.png

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited January 2018

    I checked it already in HyperCrash and HyperCrash takes it into acount. But i get the same results anyway if i change the skew. The right models skew is rotated 90° by the z-axis but the results are the same:

    <?xml version="1.0" encoding="UTF-8"?>CoreOrientation.thumb.jpg.4c7e7acdd37edcfb0d0b47bbe9d78a9a.jpg

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited January 2018

    Hi,

    In your model the material seems to be almost isotropic transverse (E11=E22). I just changed the E11 and E22 values, tried with and without skews.

    There was difference in the results.

     

     

    <?xml version="1.0" encoding="UTF-8"?>yz.PNG

    <?xml version="1.0" encoding="UTF-8"?>TF.PNG

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited January 2018

    Hi George,

     

    The shear modules are different in my model (G23=25; G13=40). So actually the shear stress results should be different if i Change the skew even if E11=E22. Do you have any idea why it does not work?

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited January 2018

    This is the same material model, with E11=E22=1; G12=25; G23=40; The shear stress is direction dependent as you can see. Therefore a Change of the skew should Change the results. In the single element case it does, but in the main_Retainer_0000.rad model it does not.

    <?xml version="1.0" encoding="UTF-8"?>Shear.thumb.JPG.d964cd607f3fec4133e30caaef43a16a.JPG

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited January 2018

    Hi George,

     

    The shear modules are different in my model (G23=25; G13=40). So actually the shear stress results should be different if i Change the skew even if E11=E22. Do you have any idea why it does not work?

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited January 2018

    Hi Huebner,

    Apologies for the delay caused. 

    If we isolate the foam component (core) , it seems that it’s working correctly that is it is given different results.

    HyperView will display the maximum stress developed in the whole model.

     

    <?xml version="1.0" encoding="UTF-8"?>12.PNG

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited January 2018

    Hi George,

     

    how exactly did you Isolate the core? Did you delete all components accept of the core in the radioss file?

     

     

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited January 2018

    Hi,

    In HyperView you can isolate the component and check the results.

     

    <?xml version="1.0" encoding="UTF-8"?>iso.PNG

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited January 2018

    When i Isolate the core i get the same results as well. Do not understand why it works in your model.

    Did you Change anything in the model? Did you change the orientation by changing the skew?

    Can you please share your model with .h3d files? 

     

    <?xml version="1.0" encoding="UTF-8"?>2222.thumb.JPG.750a3b41093e0383e8a65f80d0e9b1f2.JPG

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited January 2018

    Hello George,

    Can you please share your model with .h3d files? 

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited January 2018

    Hi,

    Actually we encountered some issue with your model and so I'm looking for some expert advice on this. I'll update you as soon as I get some updates on this.

    Thank you for understanding.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2018

    Hi George,

     

    do you have new informations regarding my issue?

     

    best regards,

    H. Huebner

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2018

    Hi Huebner,

    Still to get any update on this topic. I'll update you soon once I get some information on this.