fe-safe_04_analysis_process

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1、fe-safeanalysisprocessfe-safeanalysisprocess•Theelastically-calculatedFEAnodalstresstensorisread.•Eachofthe6componentsofthestresstensorismultipliedbythetimehistoryoftheappliedloading,toproduceatimehistoryofeachofthe6componentsofthestresstensor.•Thetimehistori

2、esofthein-planeprincipalstressesarecalculated-theout-of-planestressischeckedforpossiblecontactloading-(thefollowingstepsassumenocontact).•Thetimehistoriesofthethreeprincipalstrainsarecalculatedfromthestresses.•Forastrain-lifeanalysis(forexample,aBrown-Millera

3、nalysis),amulti-axialcyclicplasticitymodelisusedtoconverttheelasticstress-strainhistoriesintoelasticplasticstress-strainhistories.ForanS-Ncurveanalysisthisstepisomitted.fe-safeanalysisprocess•ForashearstrainorBrown-Milleranalysis,thetimehistoriesoftheshearand

4、normalstrainandtheassociatednormalstressarecalculatedonthreepossibleplanes.ForanS-Ncurveanalysisaplaneperpendiculartothesurfaceisdefined,andthetimehistoryofthestressnormaltothisplaneiscalculated.Formostmetals,fe-safeusescombinedshearandnormalstrains-theBrown-

5、MillerparameterForbrittlemetals,fe-safeusesaxialstrainsCriticalplaneanalysisisusedfornon-proportionalstressesCriticalplaneanalysisisusedfornon-proportionalstressesCriticalplaneanalysisisusedfornon-proportionalstresses-thisisalsoselectedautomaticallyOut-of-pha

6、sebiaxialstresses-non-proportionalloadingCAStrainB(ABAnglefromACriticalplaneanalysisfe-safeanalysisprocess•Oneachplanethefatiguedamageiscalculated.Foreachplanetheindividualfatiguecyclesareidentifiedusinga‘Rainflow’cyclealgorithm,thefatiguedamageforeachcycleis

7、calculatedandthetotaldamageissummed.•Theplanewiththeshortestlifedefinestheplaneofcrackinitiation,andthislifeiswrittentotheoutputfile.•Duringthiscalculation,fe-safemaymodifytheendurancelimitamplitude.Ifallcycles(onaplane)arebelowtheendurancelimitamplitude,ther

8、eisnocalculatedfatiguedamageonthisplane.Ifanycycleisdamaging,theendurancelimitamplitudeisreducedto25%oftheconstantamplitudevalue,andthedamagecurveextendedtothisnewendurancelimit.•Processi