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Tsai-Wu failure criteria, strength ratio

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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Altair Forum User

Hi @Tüki

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

Altair Forum User

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

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

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.

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Altair Forum User

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

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

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

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)

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