1、ISOInternationalStandardISO9538Thirdedition2025-06AerospaceseriesHydraulictubingjointsandfittingsPlanarflexuretestSerieaerospatialeJointsetraccordsdestuyauterieshydrauliquesEssaideflexionplaneReferencenumberISO9538:2025(en)COPYRIGHTPROTECTEDDOCUMENTISO2025Allrightsreserved.Unlessotherwisespecified,o
2、rrequiredinthecontextofitsimplementation,nopartofthispublicationmaybereproducedorutilizedotherwiseinanyformorbyanymeans,electronicormechanical,includingphotocopying,orpostingontheinternetoranintranet,withoutpriorwrittenpermission.PermissioncanberequestedfromeitherISOattheaddressbeloworISO,smemberbod
3、yinthecountryoftherequester.ISOcopyrightofficeCP401Ch.deBlandonnet8CH-1214Vernier,GenevaPhone:+41227490111Email:copyrightiso.orgWebsite:www.iso.orgPublishedinSwitzerlandContentsPageForewordivIntroductionv1 Scope12 Normativereferences13 Termsanddefinitions14 Deviceforflexuretest15 Flexuretestspecimen
4、s36 Stressdetermination37 Procedure47.1 Instrumentationandstraingauges47.2 Frequency57.2.1 Testfrequency57.2.2 Naturalfrequencyofthespecimens57.2.3 Verificationofthenaturalfrequency57.3 Bendingstresscalibrationoftestspecimen57.4 Test58 Requirements5Bibliography7ForewordISO(theInternationalOrganizati
5、onforStandardization)isaworldwidefederationofnationalstandardsbodies(ISOmemberbodies).TheworkofpreparingInternationalStandardsisnormallycarriedoutthroughISOtechnicalcommittees.Eachmemberbodyinterestedinasubjectforwhichatechnicalcommitteehasbeenestablishedhastherighttoberepresentedonthatcommittee.Int
6、ernationalorganizations,governmentalandnon-governmental,inliaisonwithISO,alsotakepartinthework.ISOcollaboratescloselywiththeInternationalElectrotechnicalCommission(IEC)onallmattersofelectrotechnicalstandardization.Theproceduresusedtodevelopthisdocumentandthoseintendedforitsfurthermaintenancearedescr
7、ibedintheISO/IECDirectives,Part1.Inparticular,thedifferentapprovalcriterianeededforthedifferenttypesofISOdocumentshouldbenoted.ThisdocumentwasdraftedinaccordancewiththeeditorialrulesoftheISO/IECDirectives,Part2(seeWWW.iso.org/directives).ISOdrawsattentiontothepossibilitythattheimplementationofthisdo
8、cumentmayinvolvetheuseof（八）patent(三).ISOtakesnopositionconcerningtheevidence,validityorapplicabilityofanyclaimedpatentrightsinrespectthereof.Asofthedateofpublicationofthisdocument,ISOhadnotreceivednoticeof（八）patent(三)whichmayberequiredtoimplementthisdocument.HoweverlImplementersarecautionedthatthism
9、aynotrepresentthelatestinformation,whichmaybeobtainedfromthepatentdatabaseavailableatWWW.iso.org/patents.ISOshallnotbeheldresponsibleforidentifyinganyorallsuchpatentrights.Anytradenameusedinthisdocumentisinformationgivenfortheconvenienceofusersanddoesnotconstituteanendorsement.Foranexplanationofthev
10、oluntarynatureofstandards,themeaningofISOspecifictermsandexpressionsrelatedtoconformityassessment,aswellasinformationaboutISOsadherencetotheWorldTradeOrganization(WTO)principlesintheTechnicalBarrierstoTrade(TBT工seeWWW.iso.org/iso/foreword.htmLThisdocumentwaspreparedbyTechnicalCommitteeISO/TC20,Aircr
11、aftandspacevehicles,SubcommitteeSC10,Aerospacefluidsystemsandcomponents.Thisthirdeditioncancelsandreplacesthesecondedition(ISO9538:2017),whichhasbeentechnicallyrevised.Themainchangesareasfollows:ClaUSe4andCIaUSe7wereupdated.Anyfeedbackorquestionsonthisdocumentshouldbedirectedtotheusersnationalstanda
12、rdsbody.AcompletelistingofthesebodiescanbefoundatWWW.iso.org/members.htmLIntroductionThetestproceduredescribedcanbeappliedasanalternativetotherotarytestprocedurespecifiedinISO7257.ThequalificationtestproceduresfortubefittingsarespecifiedinISO7169.Othertestmethodscanbeusedaslongastheydevelopthesamere
13、sultsastheprocedurespecifiedinthisdocument.AerospaceseriesHydraulictubingjointsandfittings一Planarflexuretest1 ScopeThisdocumentspecifiesaplanarflexuretestprocedureforreconnectableandpermanenthydraulictubejointsandfittings.Thisprocedureisintendedforconductingflexuretestsonfittingswithhigh-strengthhyd
14、raulictubesmadeofcorrosion-resistingSteeLtitaniumandaluminiumforuseoncommercialandmilitaryaircraft.2 NormativereferencesTherearenonormativereferencesinthisdocument.3 TermsanddefinitionsNotermsanddefinitionsarelistedinthisdocument.ISOandIECmaintainterminologydatabasesforuseinstandardizationatthefollo
15、wingaddresses: ISOOnlinebrowsingplatform:availableathttps:WWW.iso.org/obp IECElectropedia:availableathttps:WWW.electropedia.org/4DeviceforflexuretestThetestdeviceshouldbesimilartothatshowninFigUreLItshallconsistofavibrator,amanifoldtoreceivethetestspecimens,andahydraulicsupplyunitcapableofconstantly
16、maintainingthestaticoperatingpressureduringtesting,includingmonitorsinducingtheshutdownofthesystemintheeventofpressuredrop.Thenumberoftestspecimensshallbedefinedbythespecificationusedtoqualifythefitting.Key1pressuresupply2pressuregauge3testspecimenFigure 1 Set-upoftestdriveThetestspecimensareattache
17、dtooppositeendsofthemanifold,whichisrigidlymountedonthevibrator.Themanifoldshallbesodesignedandassembledthatanyrotationshallbeavoidedduringtesting.Ahoseassemblyestablishestheconnectionwiththehydraulicsupplyunit.Thevibratorshallallowforvibrationfrequenciesupto300Hz.Key1straingaugesforstresscycleasses
18、smentinthetubeduringvibration2accelerometer3pressureportmanifold4vibratorFigure 2 Detailsofset-up5 FlexuretestspecimensThetestspecimensshallconsistofthetubefittingtobetested(e.g.straightunion),thetesttubeandthefittingtosealthetube.6 StressdeterminationThemaximumpermissibleflexurefatiguestressofthete
19、sttubingisdeterminedforthecombinedstresslevel.Thecombinedstress,JfiScomposedofthetensilestress,相SUltingfromtheinternalpressureandthewallthicknessofthetube,andthebendingstress,b.Straingaugesshallbeusedtodemonstratethebendingstress;andthedeflectioncanbecheckedduringtestingbymeansofanglegauges.Atypical
20、stresscycleisillustratedinFigUre3.Thebendingstress,bisdeterminedbythemaximumpermissibleflexurefatiguestressofthetesttubeandshallbespecifiedforeachapplication.Key1maximumstress2minimumstresspmeanaxialstressproducedbyinternalpressurebstresscausedbybendingfcombinedstress,p+bFigure 3 Typicaltestcycle7Pr
21、ocedure3.1 InstrumentationandstraingaugesAstraingaugeshallbemountedoneachtestspecimen.Theyshallbeofunidirectionaltype,mountedtothetubeandorientedasshowninFigUre4,Theirlocationshouldbeasfollows:a) fortubesizestoDN16:approximately4mmfromtheattachment-pointtubetofitting;b) fortubesizestoDN20andabove:ap
22、proximately8mmfromtheattachment-pointtubetofitting.Key1 straingauge2 vibrator3 see7il4 lengthgivingnaturalfrequencyofbetween110Hzand120HzFstaticloadFigure4Locationofgauges7.2 Frequency7.2.1 TestfrequencyThetestshouldbeperformedatapproximately100Hz.7.2.2 NaturalfrequencyofthespecimensTominimizethepow
23、erinputofthevibratorused,thenaturalfrequencyofthespecimensshouldbewithinthefrequencyrange110Hzto120Hz.Thetestfrequencyshallbeapproximately10%to20%belowthenaturalfrequencyofthespecimenstopreventtheirresonancerangefrombeingreached.7.2.3 VerificationofthenaturalfrequencyThespecimenlengthshallbedetermin
24、edinorderthatthetheoreticalfirstbendingnaturalfrequencyshallbeintherangementionedin7.2.2.Theverificationofthetheoreticalnaturalfrequencyshallbeperformedaccordingtothefollowingprocedure.a) Screwthefullyassembledtube,fittedwithstraingauges,intotheheader.b) Fillthespecimenwiththetestfluid.c) Drainthesp
25、ecimeninordertoavoidanypresenceofair.d) Connectthestraingaugestothemeasuringdeviceandadjustthegaintosetthezero.e) Implementanaccelerometerontheheaderandconnectittothemeasuringdevice.f) Applythespecifiednominalpressure.g) Performasinefrequencyup-sweepscanfrom5Hzto200Hzanddown-sweepscanfrom200Hzto5Hzw
26、ithalogarithmicsweeprateofapproximately1octaveperminuteandanaccelerationpeakvalueof1g.h) Determinetheresonantfrequencyofthespecimensbypost-treatmentofthestraingaugesresponse,applythenominalpressureandvibratethetube.7.3 BendingstresscalibrationoftestspecimenSubmitthepreparedtubetoastaticload(F)corres
27、pondingtothespecifiedbendingstress(seeClause4)inordertoproducetherequiredmoment.Afterthetubebendingsettingiscomplete,introducethespecifiedpressureandreadthestresstransmittedbythestraingaugeonanoscilloscope.7.4 TestStartthevibratorandsetthefrequencyinarangeof80%to90%oftheresonantfrequencymeasuredin7.
28、2.3:increasethevibrationamplitudeofthevibratoruntiltheoscillographshowsthepreviouslydeterminedstressvalue.Anglegaugemountedontheextremityofeachspecimencanbeusedtoallowbettervisualisationofthedeflection.Tocontrolthedeflectionofthetestspecimen,asuitablestroboscopewithvariableflashfrequencyshallbeused.
29、8RequirementsTheflexuretestspecimensshallwithstandIO7cycles.Leakagesandfailuresarenotacceptable.Bibliography1 ISO7169,AerospaceSeparabletubefittingsforfluidsystems,for24degreecones,forpressuresupto3000psior21000kPaProcurementspecification,inch/metric2 ISO7257,AircraftHydraulictubingjointsandfittingsRotaryflexuretest
