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1、Ships Longitudinal Strength船舶纵向强度船舶纵向强度longitudinal经度的；纵向的lgtju:dnl船体结构必须具有抵抗各种内外力作用使之发生极度变形和破坏的能力，这种能力称为船体强度(strengthofships)。纵向强度(longitudinalstrength)是指船体结构抵抗因垂向受力沿纵向分布变化造成的总纵弯曲和剪切变形导致结构极度变形和破坏的能力。1II TextWhenashipisfloatingormovingthroughthewater,therearemanyforcesactingon作用于itshull.当船舶漂浮或对水移动时，
2、有许多种力作用在船体上。Howforcesactislargelydetermined by thekindofship.这些力是如何作用的很大程度上由船舶类型决定。Typesofforcesthatoccurarethesameforeveryship,butthemagnitudes大小andpointsofactiondepend on theshapeoftheshipshull.产生的力的类型对每条船来讲是相同的，但力的大小和作用点取决于船体形状。21.Typesofforcesthatoccurareforeveryshipwhenfloatingormovingthroughth
3、ewater.A.different不同的B.identical完全相同的C.similar相似的D.notmentioned没有提到答案：B3Thepatternofforcesonashipshullislargelydepends(dependent) on thefollowingparameters:船体所受力的形式很大程度上取决于以下参数：theweightoftheemptyship(lightshipweight),theweightanddistribution分布ofthecargo,fuel,ballast,provisions,freshwateretc.,hydro-
4、staticpressureonthehullappliedbythewater,hydro-dynamicforcesresulting from起因于 themovementoftheshiponthewaves,etc.空船重量，货物、燃料、压载水、食物、淡水等的重量及分布，海水施加在船体的静水压力，由船舶在水上移动产生的水动力等。Theseandotherforcescausetheshiptodeflect.这些力导致船舶弯曲变形弯曲变形。4Whentheforcedisappears,theshipwillregainitsoriginalshapeduetoshipshullfl
5、exibility.当这些力消失时，基于船体弹性，船舶会恢复原样。 Insomecasetheforcesexceedacertainlimit,permanentdeformation变形canoccur.在某些情况下，力超出一定限制，船体可能发生永久性的变形。Lengthofverylargecarrierexceeds300m,andespeciallyforceswithhighmagnitudesactingonitshullinlongitudinaldirection.长度超过300米的大型船舶，尤其高强度的力会作用在船体纵向。55.Whentheforcesdisappears
6、,theshipwillitsoriginalshapeduetoshipshullflexibility.A.deflect挠曲B.regain恢复C.maintain保持D.alter改变答案：B6Ship strength generally represents表示表示 the ships structural ability to resist the effects of outside forces. 一般来讲，船舶强度代表船舶结构上抵抗外力作用的一般来讲，船舶强度代表船舶结构上抵抗外力作用的能力。能力。Whenashipisincalmwater,thetotalupwardf
7、orce(buoyantforces)willequalthetotalweightoftheship(displacementoftheship)asthefirstlawofflotationstates.(SeeNote1)根据浮力第一定律，静水中船舶所受的浮力等于其重量（排水量）。7Locally局部地thisequilibriumwillnotberealizedbecausetheshipisnotarectangularhomogeneousobject.由于船舶不是箱型均匀体，这种平衡在局部上是达不到的。Thelocaldifferencesbetweenupwardpress
8、ureofbuoyancyandtheshipslocalweightgiverisetoshearing forces,Qxthatleadtolongitudinaltensionsandthebending moment,Mx.船舶局部浮力和重量的差值造成可导致纵向应力的剪力剪力Qx和弯矩弯矩Mx的产生。Thegreatestforcesmomentsandstressesthataffecttheshiphullare expressed as bendingandbucklinginthelongitudinalverticalplane.影响船体的最大力矩和应力表示为纵向垂面上的弯
9、曲变形。87.Thelocaldifferencesbetweenupwardpressureofbuoyancyandtheshipslocalweightgiveriseto.A.twistingforces扭变力(torsionalforce)B.rackingforces歪变力C.shearingforces剪切力D.transversalforces横向力答案：C9TransverseforceQxhasapositivesignvalueifitsdirectionfromupwardtodownward,andrespectively分别地Qxhasanegativesignva
10、lueincaseofadirectioncontraryto与相反thatpreviouslymentioned.如果剪力Qx方向从上向下，则取正值，相应的，如果剪力方向与前述相反，Qx取负值。Attheshipends(assateatfirstlawofflotation)transversalforcesareequaltozero.在船舶两端，剪力等于零（满足浮力第一定律）。注：剪力绝对值的最大值一般出现在距船舶首尾1/4船长处。10The bending moment on still water (SWBM) indicates how loading weight distri
11、bution affects on longitudinal strength. 静水中弯矩指示载重量分布如何影响纵向强度。静水中弯矩指示载重量分布如何影响纵向强度。Bendingmomentsvaluearealsodifferentovertheparticularcrosssection横截面,becausebesidesthedifferencebetweenbuoyancyandweightforceitself,thereisalsothedifferencebetweenthecenterofgravityoftheshipsmassatcrosssectionandcenter
12、ofgravityofsubmergedpartcrosssection.弯矩值在特定横截面也有不同，因为除了浮力与重力有差值外，船舶质量在横截面的重心与水下部分横截面的重心也有差别。注：重力对剖面的力矩不等于该侧浮力对剖面的力矩，即产生弯矩。112.onstillwaterindicateshowloadingweightdistributionaffectsonlongitudinalstrength.A.Bendingmoment弯矩B.Longitudinalstrength纵向强度C.Shearforce剪力D.Displacement排水量答案：A12Bendingmomentca
13、nbeexpressedashoggingorsaggingdeflectiondependingonitsactingdirection.弯矩由其作用方向可表示为中拱和中垂中拱和中垂。Hoggingindicatethattheverticaldeflectionofashipshull,inlongitudinaldirection,wherethehullmidshipsisbentupwards,asaresultofcargodistributionand/orthewaytheshipissupportedbyawaveatsea.中拱表明由于货物分布和/或船舶受波浪承载的形式而导
14、致的船体纵向垂直变形，船体中央部分向上拱起。138.canbeexpressedashoggingorsaggingdeflectiondependingonitsactingdirection.A.Localstrength局部强度B.Bendingmoment弯矩C.Shearforces剪力D.Deckload甲板载荷答案：B143.indicatethattheverticaldeflectionofashipshull,inlongitudinaldirection,wherethehullmidshipsisbentupwards.A.ShearingB.SaggingC.Hogg
15、ingD.Buckling答案：C15Respectively,saggingindicatethattheverticaldeflectionofashipshullinlongitudinaldirection,wherethehullmidshipsisbentdownwards,asaresultofcargodistributionand/orthewaytheshipissupportedatsea. 相应的，中垂表明由于货物分布和/或船舶受波浪承载方式引起的船体纵向垂直变形，船舶中央部分向下凹陷。注：弯矩绝对值的最大值通常出现在船中处。16Thedirectevaluationp
16、rocedurerequires,foragivenloadingcondition,aderivation求导,sectionbysection,ofverticalresultants合力ofgravitational(weight)andbuoyancyforces,appliedalongthelongitudinalaxisofthebeam.(SeeNote2)评估程序要求对于每一装载状态，沿纵向梁分段求出其上重力和浮力。ToobtaintheweightdistributionW(x),theshiplengthissubdividedintoportions:foreachof
17、them,thetotalweightandcenterofgravityisdeterminedsummingup总计contributionsfromallitemspresentonboardbetweenthetwoboundingsections.为获得船舶重量分布W(x),船舶长度细分为许多部分：对于每一部分，总重量和重心由处在两边界之间的所有物件的总和决定。17ThedistributionforW(x)isthenusuallyapproximated by a linear (trapezoidal) curvefortheconsideredshipportion.所考虑的
18、船舶部分的重量分布W(x)通常近似于线性（梯近似于线性（梯形）曲线形）曲线。 Theprocedureisusuallyappliedseparatelyfordifferenttypesofweightitems,groupingtogether集合theweightsoftheshipinlightweightconditionsandthose(cargo,ballast,consumables)typicalofaloadingcondition.这种程序通常分别应用于不同类型的重量成分，将空载船舶重量和典型装载物（货物、压载、消耗品消耗品）的重量结合在一起。 18Thepredict
19、ionofthebehavioroftheshipinwavesrepresentsakeypointinthequantification量化ofbothglobal整体andlocal局部loadsactingontheshipshull.(SeeNote3)正确估计船舶在波浪中的响应特征是量化作用在船体上的整体结构受力和局部受力的关键。Theactionofwavesmodifies修改thepressuredistributionalongthehullsurface.波浪作用可改变沿船体表面的压力分布。注：波浪会使浮力沿纵向分布发生变化。波浪中剪力与静水中剪力的差值称为波浪剪力(wa
20、veshearforce)。波浪中弯矩与静水中弯矩的差值称为波浪弯矩(wavebendingmoment)。19Thedifferentialpressurebetweenthesituationinwavesandincalmwater(weightdistributionoftheshipisunchangingandunequalbuoyancydistribution)generates产生onthetransversesectionadditionalbendingmoment.船舶在波浪中和静水中的压差（船舶重量分布不变，浮力分布不规则）在横截面产生额外的弯矩。differenti
21、al,dfren()ln.微分；差别transversesection=crosssection（截面）20Theshipispositionedonastaticalwaveofgivencharacteristicsinaconditionofequilibriumbetweenweightandstaticbuoyancy.船舶处在具有给定特性的静水当中，重量和静浮力达到平衡。staticwave=stillwaterNumerousresearcheshavedeterminedthatthebiggestwaveloadappearswhena wave length is appr
22、oximately equal to the ships length.Theshipcoursehastomatchthewavedirection.许多研究断定，当波长约等于船长，会出现最大的波浪载荷。船舶航向必须与波浪方向相同。216.Theshipispositionedonastaticalwaveofgivencharacteristicsinaconditionof?betweenweightandstaticbuoyancy.A.equilibrium平衡B.uniform统一C.distortion变形D.undulation起伏答案：A224.Numerousresearc
23、heshavedeterminedthatthebiggestwaveloadappearswhenawavelengthistheshipslength.A.greatlylargerthanB.muchsmallerthanC.approximatelyequaltoD.notrelatedto答案：C23Amongallgroupsofapproaches方法ondeterminationshipslongitudinalstrength(closed-formformulae,simplifiedanalyticalmethodsandnonlinearsimulations),the
24、aboveconsidersimplifiedanalyticalmethodsarefavoredbymostanalysts.在所有判定船舶纵向强度的方法当中（详算法、简化解析法和非线性模拟法），上述简化解析法得到大多数分析人员的青睐。 Theseapproachessavemodelingtimeandprovidereliableresults.这种方法可节省建模时间并提供可靠结果。24Asimplifiedmethodhasbeenplacedasthefirstchoiceinextensive广泛的relatedresearchofdeterminationultimatehul
25、lgirderstrength.在判定最终船体总强度的广泛相关研究中，简化解析法被作为第一选择。25Thecontinuousimprovementofknowledgeregardingthebehaviorofshipshullatvariousconditionshasledto引起thedevelopmentofvariousnewmethodsindeterminationhullgirderstrength.关于船体在不同状况中响应的知识不断发展，引起判定船体总强度的各种新方法的产生。Inrecentfewyears,therehasbeenagrowinginterestinim
26、plementingopticalfibersensorsonships.在近几年，船上实施光纤传感器的方法逐渐引起人们的兴趣。Opticalfibersensorsalsocanbeusedonshipshullstructuralmonitoringsystem.光纤传感器也可用于船体结构监控系统。26Weaim to旨在 obtainapossibilitytodeterminehullgirderstrengthusingopticalfibersensors,whichmaybeusedashandy便利的toverificationoftransverse,longitudinal
27、 andlocalstrengthforamomentaryloadingconditionandtohelpmaketimelydecisionintheeventofanemergencywhichhasbeenarisingfromaccident.我们致力于获得使用光纤传感器判定船体总强度的可能性，光纤传感器能便利验证船舶瞬时受力情况下的横向、纵向和局部强度并有助于在由事故引致的紧急情况下作出及时决定。27Task1.ReadingComprehension1.Whatfactorsisthepatternofforcesaffectedby?Theweightoftheemptysh
28、ip,theweightanddistributionofthecargo,fuel,ballast,provisions,freshwater,hydrostaticpressure,hydrodynamicforces,etc.2.Howwilltheshipactwhentheforcesceasetoexist?Regainitsoriginalshape.3.Whatistheshipstrength?Itrepresentstheshipsstructuralabilitytoresisttheeffectsofoutsideforces.4.Whatisthefirstlawof
29、flotation?Whenashipisincalmsea,buoyantforcewillequalthetotalweightoftheship.285.Whatdoesshiphoggingmean?Hoggingindicatethattheverticaldeflectionofashipshull,inlongitudinaldirection,wherethehullmidshipsisbentupwards.6.Howisshipsaggingcaused?Cargodistribution&thewaytheshipissupportedatsea.7.Howdoesdir
30、ectevaluationprocedureworkout?Itrequiresforagivenloadingcondition,aderivationsectionbysectionofverticalresultantsofgravitationalandbuoyancyforces,appliedalongthelongitudinalaxisofthebeam.298.Whendoesthebiggestwaveloadexist?Whenawavelengthisapproximatelyequaltotheshipslength.9.Whatisthebestmethodonde
31、terminationshipslongitudinalstrength?Simplifiedanalyticalmethod.10.Whatfunctiondoestheopticalfibersensoract?Itmaybeusedashandytoverificationoftransverse,longitudinalandlocalstrengthforamomentaryloadingcondition.Itcanalsobeusedonshipshullstructuralmonitoringsystem.30Task2Sagging中垂Deckload甲板载荷Strength
32、deck强力甲板Longitudinalbulkhead纵向舱壁Weightdistribution重量分布Buoyancyforce浮力Crosssection横截面SWBM=static/stillwaterbendingmoment静水弯矩Shearforce剪力Slamming砰击，波击Strengthmember强力构件311.由船底延伸到甲板的舱壁，它通过前后的横向舱壁连接到船舶两舷。(longitudinalbulkhead)2.静水中的弯矩。(SWBM)3.船壳平坦的区域与水以锐角接触，发出巨响并且船体剧烈震动。(slamming)4.船舶露天甲板装载的货物。(deckload
33、)5.船舶承受载荷的部件。(strengthmember)6.能够抵抗纵向弯曲的最上层连续甲板。(strengthdeck)7.船体中心向下弯曲。(sagging)8.船舶内部重量分布。(weightdistribution)9.流体施加的力，该力与船舶重量相反。(buoyancyforce)10.在船舶长度上的任一位置，趋向于把一部分相对于邻近部分垂向移动的力。(shearforce)11.三维物体与平面相交。(crosssection)32Task 3 Translation Exercises1.Insomecasetheforcesexceedacertainlimit,permane
34、ntdeformationcanoccur.在某些情况下，力超出一定限制，船体可能发生永久性的变形。2.Saggingindicatethattheverticaldeflectionofashipshullinlongitudinaldirection,wherethehullmidshipsisbentdownwards,asaresultofcargodistributionand/orthewaytheshipissupportedatsea.中垂表明由于货物分布和/或船舶受波浪承载方式引起的船体纵向垂直变形，船舶中央部分向下凹陷。333.Theshipispositionedonas
35、taticalwaveofgivencharacteristicsinaconditionofequilibriumbetweenweightandstaticbuoyancy.船舶处在具有给定特性的静水当中，重量和静浮力达到平衡。4.Thecontinuousimprovementofknowledgeregardingthebehaviorofshipshullatvariousconditionshasledtothedevelopmentofvariousnewmethodsindeterminationhullgirderstrength.关于船体在不同状况中响应的知识不断发展，引起判定船体总强度的各种新方法的产生。34
