Meaning of a negative failure index
Altair EmployeeHey,
I'm performing a dynamic analysis on a composite structure and i'm using the hoffman failure criterium to analyse the results.
However i'm finding negative values for this failure index and i can't find anywhere what the meaning of a negative failure index is.
Does this mean i can't draw any conclusions if the index becomes negative and if so, at what value do i need to look then?
Kind regards
Jeroen
Answers
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Hi @Jeroen DV
When ply is in compression, according to Hoffmann failure indices will be negative when: 0 < sigma < Xt - Xc
Can you share the .out file of the same run?
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Hey,
So what does it mean than if the failure index becomes negative? Does it mean you can assume the material won't fail between -1 and 1? Or can't you draw any conclusions if it becomes negative and if so, what do you have to draw conclusions in this case?
.out file of the run is attached.
Kind regards,
Jeroen
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Any idea yet on what the interpretation for the negative failure indices is yet or if we should look at other values to draw conclusions?
Kind regards,
Jeroen
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Hi @Jeroen DV
Anything below 1 is considered safe,
Try decreasing the compressive load and you would see the ply failure moving towards lower negative values,
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Okay that's good to know. We also looked at the strength ratio to get a better understanding of what happens at these negative indices.
However we don't seem to be able to view the strength ratio for a individual ply but only for the entire element.
Does this mean the strength ratio is only an indication for the entire laminate? Is it not possible to find strength ratio's for the plies?
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Do you see “Composite Strength (s)?
Select that instead of composite strength ratio to see Ply by ply results,
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Thanks for the help
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