简介:TheeffectoffrequencyandsampleshapeonfatiguebehaviorsofDZ125superalloyaresystematicallystudied.Theresultsshowthatfatiguefracturestilloccursabovethecycleof10~8fortestscarriedoutatthefrequencyoff=20kHzandstressratioR=-1,sothetraditionalfatiguelimitatcycleof10~7isnotappropriateforfatiguedesign.Fatiguefracturesurfacesareperpendiculartostressaxisforcylindricalandplatespecimens,andthefatiguecracksoriginatefromtheextrasurfaceofthespecimens.Fatiguecrackisapttopropagatefromcuttingdirectiontoforwarddirection,whichoccursmainlyinthesecondpropagationstageathigherstressamplitude.ThereisanobviousfrequencyeffectforDZ125superalloy.Thehigherthetestfrequencyis,themoreserioustheeffectoffrequencyonfatiguebehaviorsofthealloy.Afterthefrequencycorrection,theultra-highcyclefatigueS-NcurvewellcoincidewiththetraditionalfatigueS-Ncurve.
简介:Thethermalprotectionperformanceofsuperalloyhoneycombstructureinhigh-temperatureenvironmentsareimportantforthermalprotectiondesignofhigh-speedaircrafts.Byusingaself-developedtransientaerodynamicthermalsimulationsystem,thethermalprotectionperformanceofsuperalloyhoneycombpanelwastestedinthispaperatdifferenttransientheatingratesrangingfrom5℃/sto30℃/s,withthemaximuminstantaneoustemperaturereaching950℃.Furthermore,thethermalprotectionperformanceofsuperalloyhoneycombstructureundersimulatedthermalenvironmentswascomputedfordifferenthighheatingratesbyusing3Dfiniteelementmethod,andacomparisonbetweencalculationalandexperimentalresultswascarriedout.Theresultsofthisresearchprovideanimportantreferenceforthedesignofthermalprotectionsystemscomprisingsuperalloyhoneycombpanel.