船舶結構動力學

第一章緒論一、現(xiàn)代結構動力學的研究內容1、外載荷分析確定性、周期性、瞬態(tài)：動力機械，旋轉機械產(chǎn)生的激勵碰撞、爆炸、沖擊等瞬態(tài)荷載隨機性：風荷載、波浪荷載、地震荷載、車輛等路面行駛引起的荷載2、結構系統(tǒng)的動力響應時域：載荷可以是非線性的，系統(tǒng)也可以是非線性的，解析解法，數(shù)值解法頻域：目前僅能處理線性化系統(tǒng)，譜分析方法，優(yōu)點：計算效率高時頻混合分析方法：將時域解法與頻域解法的優(yōu)點結合，提高計算效率和求解精度解析法：數(shù)學上直接求解，許多實際結構難以采用該方法數(shù)值解法：工程上可以應用的近似解法，有限元法、邊界元法、隨機樣條法、有限條法13、結構系統(tǒng)的辨識和參數(shù)估計動力學的擬問題（1）已知input和output，識別結構參數(shù)（2）已知input滿足一定假設，output可測，識別結構參數(shù)（3）Healthmornitoring:a、有無結構失效

b、損傷位置

c、損傷程度SystemInputLoadsoutputResponse？InputLoadsoutputResponse24、容許標準和可靠性分析評估結構系統(tǒng)在某種載荷激勵下的可靠性，系統(tǒng)壽命評估，系統(tǒng)疲勞分析等。5、結構振動控制大型結構如高層、潛艇、海洋平臺等，環(huán)境荷載比較惡劣，在使用過程中會出現(xiàn)幅度比較大的振動。這些振動會誘發(fā)（1）疲勞破壞（2）降低系統(tǒng)的可靠度（3）給居住會作業(yè)人員帶來身體不適措施：在結構上安裝控制設備（裝置），使結構具有自動調節(jié)的能力，從而使其振動減小，避免破壞。在建筑結構中主要是抵抗風、地震載荷、橋梁的振動上海電視塔、楊浦大橋等都安裝了減振裝置，日本的200多個高層建筑海洋結構主要抵抗波浪、風荷載控制方法主要有：被動式控制：調諧質量阻尼器，調諧液體阻尼器，粘彈性阻尼器等主動控制：主動質量驅動器等半主動控制：主動變剛度，主動變阻尼，磁流變阻尼器，電流變阻尼器混合式控制6、結構動力優(yōu)化設計按照設計要求確定可控變量或設計變量使結構系統(tǒng)達到預期的狀態(tài)，或者達到最優(yōu)設計目標最優(yōu)綜合或最優(yōu)設計3SpecialtopicI:Dynamicresponse

動態(tài)響應4567不同方法計算whipping響應的比較8Springinganalysis激勵頻率固有頻率9Inwhippingandspringingthereare101112通過分析結構能量傳遞途徑，采用改變結構參數(shù)實現(xiàn)抑制振動向目標區(qū)域傳遞1314結構破壞指數(shù)15冰載測量16171819202122結構動力學的前沿和熱點問題主動控制技術海洋工程動力學海上陸色能源開發(fā)的動力學問題23IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)24SepecialtopicII:IMPULSIVEPRESSURELOADING

ANDRESPONSEASSESSMENT(V.7)

脈沖壓力載荷與響應評估2425IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)Damaged

structureduetoBowSlamming艏部砰擊下的結構損傷Damagedplate外板損傷Damagedstiffener骨材損傷INTRODUCTION2526IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)DamagedstructureduetoSternSlamming艉部砰擊下的結構損傷Damagedplate外板損傷Damagedstiffener骨材損傷2627IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)DamagedstructureduetoSloshing晃蕩引起的結構損傷DamagedcorrugationImpactedArea2728IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)DamagedstructureduetoGreenWater上浪引起的結構損傷DamagedwaterbreakerDamagedstiffener2829IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)Structuraldesignagainstimpulsivepressureloadingsfromslamming,sloshingandgreenwaterhasalwaysbeenadifficulttask.Manyshipshavestillreportedexperiencingstructuraldamageduetoimpulsivepressureloadings.Thisindicatesthattherelevantrulesofclassificationsocietiesneedstobeimprovedregardingimpulsivepressureloadings.

受脈沖壓力載荷（砰擊、晃蕩、上浪等）作用的船體結構的設計總是一件棘手的事情。到目前為止，脈沖載荷引起的結構損壞還是時有發(fā)生，表明船級社現(xiàn)行的相關規(guī)范需要進一步改進。Whenthedurationofanimpulsivepressureloadingismuchshorterthanthenaturalperiodoftheimpactedstructure,theimpulsemayrepresenttheloading.However,ifthedurationislongenoughascomparedtothenaturalperiod,theamplitudeofpressuremayplayanimportantrole.當脈沖壓力載荷的持續(xù)時間遠遠小于結構的固有周期時，可以用脈沖特性來描述載荷；當脈沖壓力載荷的持續(xù)時間遠遠大于結構的固有周期時，可以用壓力峰值來描述載荷。Inextremecases,thestructuraldesignagainstimpulsivepressureloadingsmaybetreatedasanultimatelimitstateoranaccidentlimitstateproblem.However,formoreprobablesituations,thiscanbesolvedasaserviceabilitylimitstateproblemespeciallyfromtheimpactsofslammingwherebythetolerableextentofdamageneedstobeprovided.在極端情況下，脈沖壓力載荷作用下的結構設計可以用極限強度或事故強度問題處理。但在更多的情況下，可以將該問題當作服務強度來處理。

29Modelandfull-scaletest模型和實船試驗技術

Modeltest

:模型試驗

-droptestoncontainershipsternsection(Yang,etal,2007)集裝箱船尾部剖面落體試驗 -droptestonrigidanddeformablecone-shapedsamples(Peseux,etal,2005)剛性和彈性錐形體落體試驗 -droptestonflatplate(HigoandYamada,2006)平板落體試驗 -planningcraftmodelinobliquewaves(RosenandGarme,2004)滑行艇模型斜浪中試驗

Fullscaletest:實船試驗 -deep-Vpleasurecraft(CarreraandRizzo,2005)深V型游艇 -containershipintheNorthPacificOcean(Lee,etal,2007)北太平洋集裝箱船試驗30IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)IMPULSIVEPRESSURELOADING:

LOCALSLAMMING30Numericalsimulation

數(shù)值模擬

-VOF(VolumeofFluid)andSPH(SmoothedParticleHydrodynamics) -explicitFEManalysisfor2Drigidwedge(Stenius,etal,2005)二維剛體顯式有限元法 -directcouplingofFEMandWagnerrepresentationforelasticbody ofsmalldead-riseangle(Korobkin,etal,2006a)小斜升角問題的有限元與Wagner砰擊壓力直接耦合法 -numericalsimulationoftrappedaireffects(Dobashi,2006;2007)氣墊效應數(shù)值模擬Analyticalprediction

解析計算

-publicationaboutanalyticalmethodshasbeenrareinrecentyears.很少 -analyticalsolutionfor2Dwedge(Yettou,etal.,2007)Yettou提出了一種新的解析算法31IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)IMPULSIVEPRESSURELOADING:

LOCALSLAMMING31Practicalproceduresindeterminingdesignslammingpressure確定設計砰擊壓力的實用過程

-computationalprocedurefortheanalysisofaship’smotionsinwavesandspatialmeanslammingpressures(Ould,etal.,2005)波浪中船舶運動以及平均砰擊壓力空間分布的計算流程 -numericalproceduretopredictslammingloadson offshoresupplyvessel(Schellin,2006) carcarrier(HermundstadandMoan,2005) cruiseship(HermundstadandMoan,2007)海洋工程供應船、滾裝船、游船的砰擊載荷預報流程 -feed-forwardneuralnetworktopredict horizontalforce(Fullerton,etal.,2007) peakvalueofslammingpressure(ChenandXiao,2005)利用神經(jīng)網(wǎng)絡技術預報橫向力和砰擊壓力峰值32IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)IMPULSIVEPRESSURELOADING:

LOCALSLAMMING3233IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)IMPULSIVEPRESSURELOADING:

LOCALSLAMMING局部砰擊

Pressurecoefficientsobtainedusingacommercialpackage(Yang,etal.,2007)經(jīng)典理論、經(jīng)典模型試驗、新模型試驗、CFD計算的比較33Background背景

-Ingeneral,theglobalslammingresponseneedstobecombinedwiththesimultaneouslyobtainedglobalandlocalsteadystateloadeffects,intermsofextremevaluesforultimatelimitstatechecksandcyclicloadhistoriesforfatiguedesignchecks.總體砰擊載荷響應一般與穩(wěn)態(tài)波浪載荷相疊加，用于極限強度和疲勞強度校核 -Generally,3Deffectscanreducethe2Dslammingpressureforcebyapproximately30%.Fully3Dslammingpredictionmethodsarenotreadyforuseinaglobalresponseanalysis.Correctionfactorson2Destimatesmaybeappliedtoyieldreasonablevaluesfordesign.計入三維效應可以減小30%的砰擊力，但三維砰擊理論尚不成熟。34IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)IMPULSIVEPRESSURELOADING:

GLOBALSLAMMINGMeasuredandcalculatedplammingpressure34GlobalStructuralModeling總體結構模型

-ThehullmaybemodelledbythebeamtheoryorFEshellmodels.Whileverticalbendingisrelativelywellrepresentedbybeamelements,modellingoftorsionalbehaviourofopenshipssuchascontainervesselsaswellascatamaransismorechallenging.船體結構可用梁理論或有限元模型進行分析；垂向彎曲問題可用梁理論較好的表示，但大開口船的扭轉問題和雙體船則比較麻煩 -Quiteaccurateresultsareobtainedifthebeammodelisbasedonanadvancedthin-walledgirdertheory.AmoredetailedFEmodelwillbenecessaryifthe1Dbeamistobeappliedinthedynamicanalysis,toobtainresponsevaluesespeciallyforfatiguedesign.利用先進的薄壁梁理論可以較準確的結果；對于疲勞等問題，有限元方法比一維梁理論更好 -Nopublicationsseemtohavebeenpublishedonslamminginducedtorsionalresponseofships.砰擊引起的扭轉振動問題目前未見有文章發(fā)表。

35IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)IMPULSIVEPRESSURELOADING:

GLOBALSLAMMING總體砰擊

35WhippingAnalysis:Extremevaluesforultimatestrengthdesign顫振分析：極限強度設計

-experimentontheshort-termprobabilitydistributionofthemidshipsverticalhoggingbendingmoment(DrummenandMoan,2007)通過模型試驗確定載荷的短期概率分布 -numericalandexperimentalstudytomeasureshipresponsestoextremewaveimpact.數(shù)值和試驗研究極限砰擊下的船體響應

(Minamietal.,2006) -hybridmethodforcalculatingwave-inducedlinearandnonlineargloballoadeffectsinshipswithhullflexibility(WuandMoan,2005)線性與非線性混合法 -experimentalandnumericalinvestigationoftheeffectofbowflareandsternslamminginducedwhippinginlargepassengervessels(Cusanoetal,2007)大型游船艏艉砰擊下顫振響應的模型與數(shù)值研究 -experimentontheVBMresponsetosternslammingloadsonalargemodernpassengership(Dessietal.,2007)大型豪華游船艉砰擊 -long-termanalysisofextremesloshingandwhipping-inducedpressuresandstructuralresponseoftheMarkIIIcontainmentsystemforLNG (Graczyketal,2007)MarkIII型大型LNG船圍護系統(tǒng)極端晃蕩和顫振壓力長期預報和結構響應36IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)IMPULSIVEPRESSURELOADING:

GLOBALSLAMMING總體砰擊

36WhippingAnalysis:Cyclicstresshistoryforfatigueanalysis顫振響應，疲勞分析中的循環(huán)載荷

-Fullscalemeasurements:實船試驗

Capesizeironorecarriers(Moeetal(2005)andStorhaugetal(2006))礦砂船 4000TEUcontainership(Drummenetal,2006,2007)集裝箱船 10000dwt.generalcargoship(AalbertsandNieuwenhuijs,2006)一般貨船 6800TEUcontainership(Toyodaetal.,2006) -Forcontainerships,thepredictedtotalfatiguedamageforthemidshipssectionwasapproximately50%higherthanthedamagedeterminedexperimentally.對集裝箱船，理論預報的疲勞損傷比試驗值大50%左右 -Highfrequencydamagecanbesignificantlyreducedbyincludingthesteadywavefortherelevantship.當包含穩(wěn)態(tài)載荷引起的破壞時，高頻疲勞損傷的程度相對明顯減輕。37IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)IMPULSIVEPRESSURELOADING:

GLOBALSLAMMING總體砰擊

3738IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)IMPULSIVEPRESSURELOADING:

SLOSHING晃蕩

Sloshingtestequipments試驗裝置Modelandfull-scaletests模型和實船試驗forquasifullscalemodel準實船for“intermediate”scalemodel中模型forsmallscalemodel小模型38Modelandfull-scaletests模型和實船試驗

-Smallscalemodeltestsgiveareasonableoverviewoftheoverallsloshingmotionsinsidethetankbutthelocalpressuresmeasurementsarestilldifficulttoobtainduetothehighlylocalized(intimeandspace)pressureswhichoccurduringimpact.Theproblemoftransferringthesepressurestoafullscalerepresentsabigchallenge.小模型可獲得晃蕩運動整體特征，但由于砰擊壓力在時間和空間上的特征，測量困難，轉換成實船更難 -Importantdatabasesofthequasifullscalemeasurementswererealizedusingthesetestsinvariousresearchprojects,butmanyproblemswerereportedwithrespecttotherepeatabilityofthemeasurementthatmakestheproperinterpretationanduseoftheresultsverydifficult.在不同的項目中，準實船試驗積累了很多數(shù)據(jù)，但結果離散性問題使利用和解釋這些結果變得困難 -“Intermediate”modeltestswillallowforthedetailedvalidationofthesimplifiedsemianalyticalandmoresophisticatednumericalmodels.Indeed,alltheimportantimpactparameterscanbemeasuredwithverygoodprecisionandthisallowsforpropervalidationofalltheintermediatemodellingsteps.中模型試驗可以為簡化的半解析預報方法和復雜的數(shù)值計算模型提供詳細的驗證39IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)IMPULSIVEPRESSURELOADING:

SLOSHING 晃蕩

39Numericalmodellingofhydro-structureinteractionsduringimpacts砰擊中流固耦合的數(shù)值模擬

-Evenifsomeattemptsweremadetosolvethe3Dimpactproblems,the2Dmodellingoffluidflowisusedmostoften.Onthestructuralsidethe3DeffectsoftheresponsecanbetreatedbythestandardFEMcodes

二維流動模型比三維模型更常用，結構的三維效應用有限元模擬CFDNumericalsimulationsCFD數(shù)值模擬

-themostpopularmethodsbelongtothefamilyoftheVOF(VolumeofFluid)techniqueandtothesocalledSPH(SmoothedParticleHydrodynamics)method.However,allCFDmethodssufferfromvariousnumericalproblemswhenitcomestotheevaluationofhighlylocalizedpressures.VOF和SPH法最常用，但當涉及到砰擊壓力時，所有的數(shù)值方法都存在問題40IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)IMPULSIVEPRESSURELOADING:

SLOSHING 晃蕩 V.7Typicalsloshingmotionssimulated40

41IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)IMPULSIVEPRESSURELOADING:

SLOSHING 晃蕩

Comparisonofthequasi-staticandhydroelasticstructuralresponses準靜態(tài)和水彈性結構響應41Combinedsemianalytical(fluidflow)andfiniteelement(structure)models半解析（流體）和有限元方法的組合

-Semianalyticalimpactmodelsrepresentanothertypeofmethodforsloshingimpactproblems.Theideaistoidentifythemosttypicalimpactsituationsandthensimplifytheminordertobeabletodescribethemwithsimplegeometryincludingthefewmostimportantphysicalparameters.半解析砰擊模型是晃蕩砰擊的另一類解法，找出最典型的砰擊，通過簡化，以幾個簡單但重要的物理參數(shù)去描述砰擊42IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)IMPULSIVEPRESSURELOADING:

SLOSHING 晃蕩

Aeratedimpactandcorrespondingsimplification(left-realsituation,middle-geometricalsimplification,right-mathematicalmodel42Experimentalinvestigations試驗研究-Anonintrusivequantitativevelocitymeasurementtechnique,PIV(ParticleImageVelocimetry)andBIV(BubbleImpactVelocimerty),highlightedturbulenceintensitythroughoutthedifferentphasesoftheimpingement-runup-overtoppingsequence. ThisscenariosuggestedtheapplicationofRitter’sdam-breakingflowsolutiontogreenwaterproblem.PIV測量上浪瞬態(tài)速度場，BIV測量平均速度場，潰壩理論的實用性43IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)IMPULSIVEPRESSURELOADING:

GREENWATER上浪

.

InstantaneousvelocityfieldusingPIVandmeasuredmeanvelocityfieldusingBIV(Ryuetal,2007a)43Experimentalinvestigations試驗研究-ThemodeltesttosimulatethegreenwaterscenariosforafixedFPSOindicatedthattheplungingwaveplusthedam-breakingtypeeventasthemostcommonwater-ondeckscenario,whereastheso-calledhammer-fisttypewasfoundtobethemostdangerousone.44IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)IMPULSIVEPRESSURELOADING:

GREENWATER上浪

Hammer-fisttypeevent:evolutionoftheshippedwater(Grecoetal,2007)44Numericalsimulations數(shù)值模擬

-Impactingflowfeatures:Domaindecompositiontechnique(Navier-Stokessolverwithalevelset(LS0techniqueandBEMsolver)(Grecoetal,2007)-Dambreakingproblem:Volume-of-fluid(VOF)scheme(Kleefsmanetal,2005),VOFtechniquewithafinitevolumemethod(Zhangetal,2005)andEdge-basedstabilizedfiniteelementsolverusingVOFextensions(EliasandCoutinho,2007)-Two-layerflowovertoppingafixedbodywithaverticalwall:Modifiedmarkerabdcell(MAC)method(Yamasakietal,2005)-Freesurfaceoverfixeddeckwitharoundprofile:movingparticlemethod(ShibataandKoshizuka,2007)-Watershippingproblem:smoothedparticlehydrodynamics(SPH)method(VioleauandIssa,2007)45IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)IMPULSIVEPRESSURELOADING:

GREENWATER上浪

Two-layerflowovertoppingafixedbodywithaverticalwall:Modifiedmarkerandcell(MAC)method(Yamasakietal,2005)45Loadalleviation

-PhamandVaryani(2006)comparedtheperformancesofV-shapeandvanetypebreakwatersfordifferentvaluesofthegeometricalparameters.TheyconcludedthattheconfrontinganglehaslessinfluenceinbothcasesforloadalleviationandthattheV-shapebreakwaterismoreeffectiveinsustainingpartofthewaterflowotherwisefullydirectedtowardcontainersandstructuresplacedbehind.擋浪板的效果46IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)IMPULSIVEPRESSURELOADING:

GREENWATER上浪

46Experimentalandnumericalsimulation試驗和數(shù)值模擬

-Theenergyoftheexplosiveisconsumedbytheshockwavesandagasbubbleandapproximately,60%intoshockwaveand40%tothegasbubbles.

爆炸能量的60%轉換成沖擊波，40%為氣泡

-Sturtevant(2007)describedthefullshipshocktrials(FSST)donebyUSNavy.ThecurrentFSSTpracticeconsistsofthreeUNDEXshotsof10,000poundHBXexplosivechargeweightdetonatedinseriesatlargestand-offdistancesabeamoftheship.Thecostsassociatedwiththetestcanexceed$50millionpertrial.美國海軍實船試驗，每個試驗花費5000萬美元

-Bubblecollapseunderasubmergedflatplate:RANSE(Reynolds-averagedNavier-Stokesequations)basedfinitedifferenceEquationIndependentTransientAnalysisComputerCode(Kanetal,2005)浸沒平板下的氣泡潰滅數(shù)值計算

-Shocktransparency:basiclinearmethod(Iakovlev,2006;2007)

沖擊波透射：基本線性法47IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)IMPULSIVEPRESSURELOADING:

UNDERWATEREXPLOSION水下爆炸Fullshipshocktrial(FSST)(Sturtevant,2007)47Experimentalandnumericalsimulation數(shù)值與模型試驗

-Effectofbulkcavitationandattenuationoffloatingstructuresresponse:ExplicitfiniteelementapproachwithBEM(Gong,2006) -Nearcontactcalculations:Thechinooksolverwiththelargedeformationfluid-structureinteraction(Gregson,2006) -Hullwhippingresponse:Thesource-sinkmethod(Noma,2006) -Ultimatestrengthofhullgirder:ExplicitFEMforbendingmoment,BEMforlocalpressurefrombubblejetandFEMforlocalstructuraldamage(Yasuda,2006;2005) -Explosionbubble:BEMcoupledwithstructuralFEcode(Klaseboer,2005)

Classificationsocietyrules船級社規(guī)范

-Lloyd’sRegisterRulesandRegulations(2008)describehowaship’sstructureisdesignedbytakingUNDEXintoaccount.Italsogivesgeneralinformationaboutshockwaves,bubblepulses,bubblejetsandtheireffectstostructuralresponse.Lloyd’sdefinesthreelevelsofshocknotationsfortheeffectsofaninitialshockwave.Inadditiontotheshocknotations,itdefinesdesignlevelsforwhippinginducedbyexplosionbubbleeffectsandanothernotationsforresidualstrengthassessment.英國勞氏規(guī)范（2008）有水下爆炸問題的較多規(guī)定和方法48IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)IMPULSIVEPRESSURELOADING:

UNDERWATEREXPLOSION水下爆炸

4849IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)

Cumulativeeffectofmultipleimpacts

多次沖擊變形累積DAMAGETOSTRUCTURESAND

THEIRRESIDUALSTRENGTH 結構破壞和剩余強度

Deformedshapeofstiffenedplate

加筋板變形EffectsofmultipleimpactsandTrippingofstiffener

(a)P=0.631MPa

(b)P=1.656MPa

(c)P=2.070MPa

49COMPARISONOF

CLASSIFICATIONSOCIETIESRULES 規(guī)范比較

ShipType;OILTANKER withD.W.39,000TonLBP;172.mBreadth(mld.);31.40mDraft(Scantling,mld.);10.95mBlockCoefficient;0.785DesignSpeed;14.5knot油船底部砰擊壓力下板厚沿船長分布要求（四個規(guī)范）50IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)Requiredthicknessofthebottomplatebythebottomslammingpressure50ShipType;OILTANKER withD.W.39,000TonLBP;172.mBreadth(mld.);31.40mDraft(Scantling,mld.);10.95mBlockCoefficient;0.785DesignSpeed;14.5knot油船艏外飄砰擊壓力下板厚沿高度分布要求（四個規(guī)范）51IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)Requiredthicknessofsideshellplatebybowflareslammingpressure5152IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)H(TankHeight)=15.1mLc(Longitudinaldistanceofthetank)=17.40mbc(Transversedistance

ofthetank)=24.94mh(FillingHeight)=10.57m(0.7H)Calculatedpoint=10.57m(0.7H)油船晃蕩砰擊壓力下的板厚比較（橫艙壁，縱艙壁）CalculatedpointClassAClassBClassCCSRTransverseBulkhead9.508.936.516.35LongitudinalBulkhead9.5010.958.608.60Requiredplatethicknessbysloshingpressure(mm)5253IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)Requiredthicknessofthedeckplatebygreenwaterloads上浪砰擊下的甲板厚度要求53Impulsivepressureloadsgeneral

Eventhoughsignificantprogresshasbeenmadeoverthelastdecade,theproperdeterminationofrelativeimpactgeometry,relativevelocityandamountofentrappedairstillremainsextremelychallenging,sincetheoverallsea-keepingproblemofshipsailingwitharbitraryforwardspeedinwavesisstillanopenproblem.由于船舶航行條件的復雜性，砰擊過程中的相對砰擊面、速度、氣墊等的確定仍然存在困難Localslamming

Numericalpredictionsofslammingpressuresaccountingforviscousflowseparation,entrappedair,compressionoffluidsandelasticityofstructuresneedtoenhancetheiraccuracy,stabilityandefficiency.Morevalidationswithtestsresultsareneededfortheapplicationofthesemethodsindesignpractice.對局部砰擊，數(shù)值計算方法的精度、穩(wěn)定性和計算效率需要進一步提高，為提高這些計算方法的實用性，試驗驗證工作需要加強

54IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)54Globalslamming

Generally,3Deffectscanreducethe2Dslammingpressureforcesignificantly.Fully3Dslammingpredictionmethodsarenotreadyforuse.Correctionfactorson2Destimatesmaybeappliedtoyieldreasonablevaluesfordesign.

Thecontributionfromvibratoryresponsemaydoublethefatiguedamageinducedbywave-frequencyloads.Thedampingmayplayanimportantroleinnumericalanalysisandmeasurements.Therefore,itisimportanttocontrolthedampinginmodelteststocorrespondtothatforrealships.對總體砰擊，計入三維效應可明顯降低二維砰擊載荷，但三維計算方法還不成熟，二維方法加三維修正可以得到更合理的設計值高頻振動響應引起的疲勞損傷可與波頻載荷相當，其中阻尼的作用很大，因此在模型試驗中考慮阻尼與實船的相似性很重要。55IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)RECOMMENDATIONSFOR

STRUCTURALDESIGNGUIDANCE結構設計指導性意見V.755Sloshing

TheFroudescalinglaw,whichisusuallyappliedforsmallscalemodeltests,yieldsconservativevaluesformaximumpressure.However,thetimeisalsodifferentlyscaledbyvariousscalinglaws.Therefore,theeffectofscalingthepressuretimehistoriesmayonlybeassessedbyanalyzingthedynamicresponseofthecontainmentsystem.

Inspiteoftheeffortstoproperlysolvethesloshingimpactissues,manykindofuncertaintiesstillpersist.ThefullscalemonitoringoftherealLNGshipsundernormaloperationwouldcertainlybeveryhelpfulbutitseemstobeverydifficulttoperform.對于晃蕩，按Froude相似率進行模型試驗將使最大壓力幅值偏大。LNG船的實船試驗十分重要但也十分困難。56IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)56Greenwater

Forwatershippingproblems,abenchmarkingsystemwouldbeappreciabletocomparebothaccuracyandcomputationalcosts.Inthisperspective,thedam-breakproblemseemstobetheobviouscandidatetoprovideasharedsetofdata.

Iftheultimateobjectiveistoprovideloadstobeappliedtotheshipsuper-structures,themeasurementofgloballoadsonflexibledecks,aswellaswalls,shouldbesuccessfullyexploitedtofacilitatethecomparisonbetweensimulationsandexperiments.

對于上浪，計算精度和效率的相互比較驗證很有意義，潰壩問題是個很好的比較對象。

57IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)RECOMMENDATIONSFOR

STRUCTURALDESIGNGUIDANCE

結構設計指導性意見57Impulseshape

Theeffectsofthetailpartontheextentofdamageisverysmallandthepeakpressureandthepeakwidtharetwomostinfluentialparameters.Unfortunately,mostoftheexperimentalortheoreticalinvestigationsreportedarefocusedonhowtoaccuratelypredictthepeakpressurebutthoseonthepeakwidthareveryfew.砰擊峰值和持續(xù)時間對結構損壞很重要。58IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)Idealisedimpulsivepressurehistory58Multipleimpacts

Eveninasinglestorm,shellplatesofshipscanbeimpactedseveraltimes.However,theextentofdamagecanbeaccumulatedbymultipleapplicationsofimpact.Theeffectsofmultipleimpactsontheextentsofdamagehavenotyetbeenconsideredinanyclassificationsocietiesrules. Accordingtosomeexperimentalandnumericalinvestigationresults,theincreasedextentofdamageofplatesduetomultipleimpactscanbeapproximately50%.

多次砰擊造成的結構累積損壞問題尚未得到重視Torsinalstrengthofstiffener

Thetorsionaldeformationsofstiffenersof damagedpartshavebeenclearlyseen. Therefore,anycriteriashouldbeprovided withwhichtorsionalstrengthofthestiffener canbechecked.Deploymentofadditional trippingbracketsintheregioncanbe apracticalmeasurewhereimpulsiveloadings areexpected.縱骨扭轉強度問題應該引起重視

59IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)Deploymentexampleoftrippingbrackets59Allowableextentofdamage

Avoidingdamageduetoimpulsivepressureloadingsdoesnotseempractical.Therefore,specifyingtheallowableextentofdamageduetoimpulsivepressureloadingsseemsnecessaryformorerationalandpracticalstructuraldesign.Whendeterminingtheallowableextentofdamage,someoptimisationproceduresneedtobeinvokedconsideringtheinitialconstructioncosts,operationalexpensesanddirectandindirectrepaircosts.完全避免結構在脈沖壓力下的損壞無法實現(xiàn)，應該提出許用損壞概念Reverseengineeringofdamagerecords

Whenpredictingtheimpulsivepressureloadingsinducedbyimpulsivepressureloadings,therearestillintolerableuncertaintieswhichexisteventhoughvariousresearchmethodshavebeenperformedtoimprovetheaccuracyofassessments.Theactualdamagerecordsmayunveilvaluableinformationwhichcouldhelpimproverelatedtechnologiesandpredictionaccuracyaccordingly.

實船損壞記錄對改進預報方法和結構設計十分重要60IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)60Localslamming

Modelorfull-scaletestsarestillthemostreliableapproachinobtainingthepressuredistributionandforceontemporalandspatialscales.However,duetothecomplexityoftheslammingphenomenon,practicalmethodstoobtainrationaldesignpressures,forcesandstructuraldynamicresponsesforanewdesignisstillrequired.對局部砰擊，模型和實船試驗仍是最可靠的手段Globalslamming

The3Dcharacterofthebowandbulbofcontainershipsisparticularlychallengingtomodel.Themainchallengeinestimatingglobalslammingresponseisthecalculationoftheslammingforce,especiallyinobliqueseasduetotheeffectsofrollingmotion.

Thehighfrequencyfatiguedamageduetowhippingcanbesignificantlyreducedbyincludingthesteadywavefortherelevantvessel.Therefore,moreworkneedstobedonetoimprovethehighfrequencystressmodeling,whichincludesidentifyingandquantifyingthesourcesofdampingofthevibrationaswellasverificationoftheexcitationsourcesofhighfrequencyresponse.對于總體砰擊，斜浪中的砰擊問題、三維砰擊問題仍然困難；高頻振動阻尼和激勵源確定很重要。61IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)CONCLUSIONS結論61Sloshing

Whenanalysingsloshingimpacts,thestructuralresponseshouldbetakenintoaccount.Animportantconsiderationisthetimescaleofaparticularhydrodynamiceffectrelativetowetnaturalperiodsforstructuralmodescontributingsignificantlytolargestructuralstresses.Morestructuralmodesmaybeincludedformembranestructuresanalysesthanforsteelstructures.

Thequasifullscalemodeltestsandintermediatescalemodeltestsarebelievedtobringmorelightintothisdifficultproblem.Severalexperimentalcampaignsarenowunderway,butstillnoclearandreliableresultshavebeenpublished.對于晃蕩，分析中必須計入結構響應，特別是當水動力時間特征和濕結構的固有頻率相近時62IMPULSIVEPRESSURELOADINGANDRESPONSEASSESSMENT(V.7)62Greenwater

Differentmeasurescanbeinvestigatedtoreducetheeffectsofgreenwateronthedeck.Forwardprotectionmaybeachievedintheformofforecastleandbreakwater,sideprotectionbymeansofwalls,ingeneralstructuralb