Thefatiguelifeofdynamicflexiblerisersisinmostcasesperformedbyathreestepprocedure:(1)Aglobalanalysisinordertoobtaintimeseriesoftension,curvaturesortensionandendanglesrepresentingtheannualfatigueload.(2)Alocalstressanalysistransformingtheglobalquantitiesint...[繼續閱讀]

    Usingtheprinciplesoutlinedin(SinesandWaisman,1959)onewayofformulatingthecriterionforamulti-axialfatiguefailurecanbestatedintermsoftheVonMisesequivalentstressrangeas:TheconstantsA,αandβcanbedeterminedfromfatiguetestingatthreedifferentmeanstresslevels,i.e.e...[繼續閱讀]

    Aflexibleriserhangingfromafloaterwillbeexposedtocyclicloadsfromtopmotionsandhydrodynamiceffectsresultingintensionandcurvaturevariations.Thisresultsindynamiclongitudinalandshearstressesinthetensilearmourwherethelongitudinalstressrepresentsthemostimportantc...[繼續閱讀]

    Themeananddynamicstressesinthepressurearmourincludethethree-dimensionalstressstatewheretheσ11,σ22,σ33andσ23arethegoverningcomponentsasoutlinedinSection4.4andSub-section4.5.4.Thestresslevelsandassociatedvariationsaresensitivetothecross-sectiongeometryandlo...[繼續閱讀]

    Undertheconditionthatsometensilearmourwiresfailinonelayerduetocorrosionorcorrosionfatigue,thiswillhaveseveralconsequences:(1)Theaxialforcecapacitywillbereduced.Hence,foragiventruewalltension,axialelongationtakesplace;(2)Tokeepthetorsionbalance,atorsionrot...[繼續閱讀]

    Corrosionwillreducetheinertiamomentofthecross-sectionandhencereducethelateralbucklingcapacity,seeEq.4.82.Ifanevencorrosionfactorcisassumedsothatthecorrodedwirewidthb*＝b(1-2c)andthecorrodedwirethicknessist*＝t(1-2c),andthentheassociatedlateralbucklingcapaci...[繼續閱讀]

    Fordynamicrisersthegoverningloadcontributionisnormallyassumedtobe1stand2ndorderwaveandcurrentloadsincombinationwithassociatedfloatermotions.InadditionVIVmayalsobeofconcern,however,accordingtothestateofartoftodaywaveandVIVloadingsrequiredifferentresponsemo...[繼續閱讀]

    GeneralFEsoftwaresuchasANSYSⓇ,MARKⓇ,ABAQUSⓇhavebecomeincreasinglypopularwithregardtoanalysingstressesinflexiblepipes.Themajoradvantageofthesetoolsisthatarbitrarygeometry,kinematicandmaterialeffectscanbemodelled.However,duetothelargenumbe...[繼續閱讀]

    Axi-symmetricstressanalysisofflexiblepipescanbecarriedoutbyseveralapproaches:(1)Byanalyticalmethods;(2)ByuseofgeneralFEsoftware;(3)Byspecializedsoftwarebasedontheconcentriclayerapproach.Fortheburstingandtensionfailuremodesthegapsbetweenlayerswillbeclosedb...[繼續閱讀]

    Tensileandpressurearmourbendingstressanalysiscanbecarriedoutbyseveralapproaches:(1)Byanalyticalmethods;(2)ByuseofgeneralFEsoftware;(3)ByspecializedFEsoftware.1.TensilearmourAnalyticalmethodsaccordingtotheprinciplesoutlinedinSection4.5iswidelyusedintheindu...[繼續閱讀]