How is Composite Failure Index calculated?

Hello everyone,

I am currently working with Hypermesh/Hyperview and Optistruct. I was wondering, how the Composite Failure Index is calculated exactly. I know the other failure mechanims (Hill, Hashin...) since there is a lot of documentation online. But I want to know the equations and the general math behind the composite failure index. Is there any explanation available?

Thank you very much!

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HyperMesh

HyperView

OptiStruct

v2024.1.0

Accepted answers

Panagiotis Kantouris_22471

Hello Fabian,

Composite Failure Index: Failure Index, plots the maximum value of the all the "Composite Failure (respective criterion)" of the different criteria and modes that you have available in you analysis.

For example in your case in every element it will check the different failure of the criteria Hashin, Hill and Tsai across all the plies and will plot the highest one. As you can understand when you have only one failure criteria in your analysis then you can get the same result by plotting "Composite Failure (respective criterion)" and by selecting Layer: "max".

I hope that this was helpful!

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Panagiotis Kantouris_22471

Hello Fabian,

You can check here for further information about the equations behind the different failure criteria that we support.

If you need any further assistance please let me know.

Thanks!

Fabian_21866

Thank you for your answer,

I am aware of all the failure criterions, but it seems like "Composite Failure Index" is more of a generic prediction or combination of many criterions. Because "Composite Failure (respective criterion)" is the failure according to the criterion you activated.

But where does this index come from? Since it proved to be very accurate for my usecases.

Thank you very much!

Panagiotis Kantouris_22471