Fatigue Analysis Certainty of Survival

inasiopo
inasiopo New Altair Community Member
edited October 2020 in Community Q&A

Dear all,

 

What is the equation for dropping test data in a fatigue analysis with standard deviation (Se) and certainty of survival (SurvCert). In our understanding this equation should be:

 

LogS(new) = LogS(data) + Se*Cert

 

Where Cert=-1 for 84% SurvCert, -2 for 97.7% SurvCert  and -3 for 99.9% SurvCert

 

However the results we are getting are not what expected, and we can't validate what we see from the results.

Also, in the manual we cannot find the used equation for dropping the data.

 

We would appreciate any help on the matter, or if someone can confirm what optistruct is using (what equation) to drop the data.

 

Many thanks.

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited May 2018

    Hi @inasiopo

     

    Can you share the results of analysis and reference so that we can have a look and check where the problem is?

    Please use the file transfer link in my signature to share the model file

     

     

    As per the OptiStruct document SVERCERT ranges from 0 to 1.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited May 2018

    @inasiopo

     

    You can use a standard error of 0.334 and survival cert to .084 (for example, meaning 84%) to start with and check the results, 

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