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Author Topic: margins of safety question  (Read 19086 times)

Paul Wagner

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margins of safety question
« on: October 29, 2009, 06:11:14 PM »
Sometimes there is a discrepancy between the minimum margin of safety reported in the "Group Design Bounds and Component Result" box in the upper right corner of the sizing form and the minimum margin indicated by the blue circle on the Failure tab.

In version 5.7.8, sometimes the minimum margin didn't match any listed on the Failure tab.  Version 5.8.11 added a pull down control to choose "Controlling LC" or "Lowest MS", so now it shows up with "Lowest MS".

I've pulled information from the AnalysisResult objects using automation and the MsTheoreticalLimit/MsTheoreticalUltimate margins agree with the Failure tab when "Controlling LC" is selected.  "Lowest MS" appears to display the MsLimitAnalysisMin/MsUltimateAnalysisMin margins and they seem to be used in the "Group Design Bounds and Component Result" box.

In my situation I have only one load case, so I'd expect them to be the same, but they're not.

The discrepancies carry over into the stress report where some of the summary table margins don't agree with the sample calculations.

Please explain these two sets of margins and why they are different when there is only one load case.

Screen shots of the sizing form are attached.