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How is composite failure index calculated?

Hello,

Id like to know how exactly is composite failure index calculated? I have some grasp of failure theories but i am not how failure index works. I know that it shows value for the worst ply of laminate but values of what exactly? I checked values for some elements and sometime value of index equals value of STRS criteria and sometime it equals value of STRN criteria. So does it not only shows value for the worst ply but also worst criteria? If so then does it consider every requested criteria? hoff tsai etc.

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Brett Ramsey_20633

The online documentation is pretty extensive. I looked a little and found a few things that may further your understanding.

Hope this helps

Gimmicks

The online documentation is pretty extensive. I looked a little and found a few things that may further your understanding.

Hope this helps

Thank you for your time but i don't think that it answers my question. I know how to calculate failure criteria (Tsai-Wu, Hill etc.), id just like to know what does Composite Failure Index (not composite failure (hill) etc.) value mean.

Brett Ramsey_20633

Thank you for your time but i don't think that it answers my question. I know how to calculate failure criteria (Tsai-Wu, Hill etc.), id just like to know what does Composite Failure Index (not composite failure (hill) etc.) value mean.

Failure indices are based on the method you choose. Their definitions are related to the allowable stress/ strain. A value less than 1 means it is within allowable limits. A value higher than 1 means the allowable stress has been exceeded. The allowable stress/ strain are the values you specify by the material.

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