4.7.1 General

    Thefatiguelifeofdynamicflexiblerisersisinmostcasesperformedbyathreestepprocedure:(1)Aglobalanalysisinordertoobtaintimeseriesoftension,curvaturesortensionandendanglesrepresentingtheannualfatigueload.(2)Alocalstressanalysistransformingtheglobalquantitiesint......查看详细>>

标签:海洋工程柔性立管与海底管道

4.7.2 Mean stress correction

    Usingtheprinciplesoutlinedin(SinesandWaisman,1959)onewayofformulatingthecriterionforamulti-axialfatiguefailurecanbestatedintermsoftheVonMisesequivalentstressrangeas:TheconstantsA,αandβcanbedeterminedfromfatiguetestingatthreedifferentmeanstresslevels,i.e.e......查看详细>>

标签:海洋工程柔性立管与海底管道

4.7.3 Mean and dynamic stresses in the tensile armour

    Aflexibleriserhangingfromafloaterwillbeexposedtocyclicloadsfromtopmotionsandhydrodynamiceffectsresultingintensionandcurvaturevariations.Thisresultsindynamiclongitudinalandshearstressesinthetensilearmourwherethelongitudinalstressrepresentsthemostimportantc......查看详细>>

标签:海洋工程柔性立管与海底管道

4.7.4 Mean and dynamic stresses in the pressure armour

    Themeananddynamicstressesinthepressurearmourincludethethree-dimensionalstressstatewheretheσ11,σ22,σ33andσ23arethegoverningcomponentsasoutlinedinSection4.4andSub-section4.5.4.Thestresslevelsandassociatedvariationsaresensitivetothecross-sectiongeometryandlo......查看详细>>

标签:海洋工程柔性立管与海底管道

4.7.5 The effect of corrosion failures in terms of bursting and fatigue performance

    Undertheconditionthatsometensilearmourwiresfailinonelayerduetocorrosionorcorrosionfatigue,thiswillhaveseveralconsequences:(1)Theaxialforcecapacitywillbereduced.Hence,foragiventruewalltension,axialelongationtakesplace;(2)Tokeepthetorsionbalance,atorsionrot......查看详细>>

标签:海洋工程柔性立管与海底管道

4.7.6 The effect of corrosion in terms of lateral wire buckling

    Corrosionwillreducetheinertiamomentofthecross-sectionandhencereducethelateralbucklingcapacity,seeEq.4.82.Ifanevencorrosionfactorcisassumedsothatthecorrodedwirewidthb*＝b(1-2c)andthecorrodedwirethicknessist*＝t(1-2c),andthentheassociatedlateralbucklingcapaci......查看详细>>

标签:海洋工程柔性立管与海底管道

4.7.7 The link between global and local analysis

    Fordynamicrisersthegoverningloadcontributionisnormallyassumedtobe1stand2ndorderwaveandcurrentloadsincombinationwithassociatedfloatermotions.InadditionVIVmayalsobeofconcern,however,accordingtothestateofartoftodaywaveandVIVloadingsrequiredifferentresponsemo......查看详细>>

标签:海洋工程柔性立管与海底管道

4.8.1 General

    GeneralFEsoftwaresuchasANSYSⓇ,MARKⓇ,ABAQUSⓇhavebecomeincreasinglypopularwithregardtoanalysingstressesinflexiblepipes.Themajoradvantageofthesetoolsisthatarbitrarygeometry,kinematicandmaterialeffectscanbemodelled.However,duetothelargenumbe......查看详细>>

标签:海洋工程柔性立管与海底管道

4.8.2 Axi-symmetric stress analysis

    Axi-symmetricstressanalysisofflexiblepipescanbecarriedoutbyseveralapproaches:(1)Byanalyticalmethods;(2)ByuseofgeneralFEsoftware;(3)Byspecializedsoftwarebasedontheconcentriclayerapproach.Fortheburstingandtensionfailuremodesthegapsbetweenlayerswillbeclosedb......查看详细>>

标签:海洋工程柔性立管与海底管道

4.8.3 Bending and fatigue stress analysis

    Tensileandpressurearmourbendingstressanalysiscanbecarriedoutbyseveralapproaches:(1)Byanalyticalmethods;(2)ByuseofgeneralFEsoftware;(3)ByspecializedFEsoftware.1.TensilearmourAnalyticalmethodsaccordingtotheprinciplesoutlinedinSection4.5iswidelyusedintheindu......查看详细>>

标签:海洋工程柔性立管与海底管道