Tsai-Wu failure criteria, strength ratio

Altair Forum User
Altair Forum User
Altair Employee
edited December 2021 in Community Q&A

Hey Guys!

 

I would like to use Tsai-Wu failure criteria for composite analysis and I have two questions about it. I would like to know which is the maximal load that my composite system can handle, so which load occurs that the failure index is equal to 1? How can I model it?

Failure index isn't suitable to scale my design therefore I would like to know the strength ratio of my composite elements. How can I get the proper strength ratios values? (I did not find the proper output card for this matter).
You can see the Tsai-Wu failure theory and the strength ratio calculating method in my attachment.

Thanks for answers in advance!

Best regards,

Tüki

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<?xml version="1.0" encoding="UTF-8"?>Untitled2.png

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited October 2017

    Hi @Tüki

     

    You can output Strength ratio using PARAM>>SRCOMPS which is available in Analysis page>> Control cards. 

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited October 2017

    Hi @Tüki

     

    You can output Strength ratio using PARAM>>SRCOMPS which is available in Analysis page>> Control cards. 

    Thanks for quick answer Prakash!

    Do you know the answer to my other question? It would be very convenient to me if I could know the load that belongs to F.I.=1 which is the failure load.
     

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited October 2017

    Hi,

     

    Failure index less than 1 indicates that failure of composite is not taken place.

    But it is also good to look at Strength ratio as failure index is not a linear function. 

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited October 2017

    Hi,

     

    Failure index less than 1 indicates that failure of composite is not taken place.

    But it is also good to look at Strength ratio as failure index is not a linear function. 

    Hey,

     

    Yes, I understand that, but I would like to know which load occurs that F.I.=1.

    I would like to test a coupon of composite and experiment the effect of the ply angle on the failure load as you can see on the attached image. If I want to know the failure load to a ply angle I have to make a lot of runs with Optistruct. I want that kind of analysis which tells me the proper failure load (where F.I.=1) to a simple rectangle shaped coupon (you can see my second attached image). If there's a method for solve this problem it would be accelerate my process.
    Thanks for the answer in advance! I hope I could draw up the problem clear.

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

    <?xml version="1.0" encoding="UTF-8"?>Capture2.PNG

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited October 2017

    Hi,

     

    OK, I understood. You want to know the failure load where failure occurs. 

     

    I will check and will let you know soon. 

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited October 2017

    Hi,

     

    Sorry for a late reply. I could not able to find a way in OptiStruct which provides the maximum load required.

     

    But you can multiply the applied load with strength ratio which provides maximum load to failure (which should make SR= 1 and FI =1)

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited October 2017

    Hi,

     

    Sorry for a late reply. I could not able to find a way in OptiStruct which provides the maximum load required.

     

    But you can multiply the applied load with strength ratio which provides maximum load to failure (which should make SR= 1 and FI =1)

    Hello Prakash!

    Thanks for your kindly help. I couldn't find a way either, but multiply the applied load seems to me an easy viable method. :)/emoticons/default_smile.png' srcset='/emoticons/smile@2x.png 2x' title=':)' width='20' />

  • Mahesh_22441
    Mahesh_22441 New Altair Community Member
    edited December 2021

    Hi,

     

    Sorry for a late reply. I could not able to find a way in OptiStruct which provides the maximum load required.

     

    But you can multiply the applied load with strength ratio which provides maximum load to failure (which should make SR= 1 and FI =1)

    Hello Prakash!

    Thanks for your kindly help. I couldn't find a way either, but multiply the applied load seems to me an easy viable method. :)/emoticons/default_smile.png' srcset='/emoticons/smile@2x.png 2x' title=':)' width='20' />

    Hi I am getting SR of the orders of e8 (FI=0.8) what could be the issue? (model has RBE2 elements)

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