SimSolid Fatigue Analysis - Survival Certainty

clivehh
clivehh Altair Community Member
edited June 2021 in Community Q&A

According to the HELP survival certainty is shown as the following, and must be entered as decimal equivalents (ie. 0.50, etc:

image

My questions are:

  1. does this relate directly to the reduction factor Creliability in the standard overall Fatigue Reduction Factor as per a hand-calculated solution for a synthetic SN-curve? (using say Norton's method of solution)
  2. if it does, then the previous input, Fatigue Strength Reduction Factor, must then be obviously reduced by that amount or there is a possibility of squaring up the effect?
  3. Why does SimSolid then accept a value of 0 for input of this value - surely from mathematical POV this would result in a singularity?
  4. Is there anyway of accessing the RainFlow Count data output from a Variable Cycle input for a SimSolid Fatigue study iro a 3D matrix response, or even a 2D data list?
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Answers

  • Evan Brennan_20557
    Evan Brennan_20557 New Altair Community Member
    edited June 2021

    Hi Clive, thanks for using the Community to ask this question.

    1/2. I'm not sure of that specific reduction factor. I think that's more related to the Fatigue Strength Reduction Factor which is a coefficient of fatigue endurance limit the same way surface treatments are.

    3. The Certainty of Survival that is input must be between 0 and 1 and represents a percentage (0.5 = 50% in the table). This value is converted to a z-factor (as seen in the table) which is multiplied by the Standard Error to shift the SN curve and account for scatter in the material data. You can see the equation for this below. So a value of 0 would just cause no change to the SN result. Also, if the Standard Error is 0 in the material data, then any change to this value will be multiplied by 0 and cause no change.

    image 

    4. Currently no there is no way to view the rainflow data. 

     

    Hope that helps!

    Evan

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