断裂力学1绪论课件

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1、Shanghai University断裂力学Fracture Mechanics郭战胜郭战胜我的联系方式E-mail：办公地点：延长校区办公地点：延长校区 力学所力学所317室室断裂力学第一讲我的希望希望大家喜欢希望大家喜欢希望大家喜欢希望大家喜欢希望大家参与希望大家参与希望大家参与希望大家参与 勇于回答问题勇于回答问题勇于回答问题勇于回答问题 勇于提出问题勇于提出问题勇于提出问题勇于提出问题 勇于参与讨论勇于参与讨论勇于参与讨论勇于参与讨论希望大家能够有所收获希望大家能够有所收获希望大家能够有所收获希望大家能够有所收获 收获一点新意收获一点新意收获一点新意收获一点新意断裂力学第一讲课堂讲授

2、课堂讨论课外学习研究课外个别学习指导与互动断裂力学第一讲考试、考核方法1.1.期末考试：考试内容期末考试：考试内容期末考试：考试内容期末考试：考试内容课外作业课外作业课外作业课外作业 考试方式考试方式考试方式考试方式笔试，闭卷笔试，闭卷笔试，闭卷笔试，闭卷 成绩认定成绩认定成绩认定成绩认定7070分。分。分。分。2.课外作业课外作业课外作业课外作业 ：成绩认定：成绩认定：成绩认定：成绩认定2020分分分分3.3.平时分：平时分：平时分：平时分：1)1)课堂表现：课堂表现：课堂表现：课堂表现：5 5分；分；分；分；2)2)出勤：出勤：出勤：出勤：5 5分。分。分。分。断裂力学第一讲解决问题的四个

3、步骤l l问题陈述-StatetheProbleml l计划求解（数学化、模型化)-PlantheSolutionl l求解-CarryOuttheSolutionl l结果判断、评价-ReviewtheSolution1.)Developbasicfundamentalunderstandingoftheeffectsofcrack-likedefectsontheperformanceofaerospace,civil,andmechanicalengineeringstructures.2.)Learntoselectappropriatematerialsforengineerings

4、tructurestoinsuredamagetolerance.3.)Learntoemploymodernnumericalmethodstodeterminecriticalcracksizesandfatiguecrackpropagationratesinengineeringstructures.4.)Gainanappreciationofthestatusofacademicresearchinfieldoffracturemechanics.Course Objectives 教材及参考书目程靳，赵树刚程靳，赵树刚程靳，赵树刚程靳，赵树刚 编编编编.断裂力学断裂力学断裂力学断

5、裂力学.北京：科学出版社，北京：科学出版社，北京：科学出版社，北京：科学出版社，20062006王铎，杜善义王铎，杜善义王铎，杜善义王铎，杜善义 编编编编.断裂断裂断裂断裂力学力学力学力学.哈尔滨：哈尔滨：哈尔滨：哈尔滨：哈尔滨工业大学哈尔滨工业大学哈尔滨工业大学哈尔滨工业大学出版社，出版社，出版社，出版社，19891989范天佑范天佑范天佑范天佑.断裂理论基础断裂理论基础断裂理论基础断裂理论基础.北京：科学出版社，北京：科学出版社，北京：科学出版社，北京：科学出版社，20032003王自强，陈少华王自强，陈少华王自强，陈少华王自强，陈少华.高等断裂力学高等断裂力学高等断裂力学高等断裂力学.北

6、京：科学出版社，北京：科学出版社，北京：科学出版社，北京：科学出版社，20092009杨卫杨卫杨卫杨卫.宏微观断裂力学宏微观断裂力学宏微观断裂力学宏微观断裂力学.北京：国防工业出版社，北京：国防工业出版社，北京：国防工业出版社，北京：国防工业出版社，19951995断裂力学第一讲绪论结构失效的类型TypesofstructuralfailureHistoryoffracturemechanicslIntheearlydaysofWorldWarII.theUnitedStateswassupplyingshipsandplanestoGreatBritainundertheLend-Lease

7、Act.Britainsgreatestneedatthetimewasforcargoshipstocarrysupplies.TheGermanNavywassinkingcargoshipsatthreetimestheratealwhichtheycouldbereplacedwithexistingship-buildingprocedures.LibertyshipsArthurM.HuddelloneofthelastWorldWarIILibertyshipslUndertheguidanceofHenryKaiser,afamousconstructionengineerwh

8、osepreviousprojectsincludedtheHooverDam,theUnitedStatesdevelopedarevolutionaryprocedureforfabricatingshipsquickly.Thesenewvessels,whichbecameknownastheLibertyships,hadanall-weldedhull,asopposedtotherivetedconstructionoftraditionalshipdesigns.lTheLibertyshipprogramwasaresoundingsuccess,untilonedayin1

9、943,whenoneofthevesselsbrokecompletelyintwowhilesailingbetweenSiberiaandAlaska.SubsequentfracturesoccurredinotherLibertyships.Oftheroughly2700libertyshipsbuildduringWorldWarII,approximately400sustainedfractures,ofwhich90wereconsideredserious.In20shipsthefailurewasessentiallytotal,andabouthalfofthese

10、brokecompletelyintwo.S.S.SchenectadyOn16January1943,Withoutwarning,andwithanoiseaudibleforatleastamile,thehullcrackedalmostinhalf.Onlythebottomplatesoftheshipheld.Thiswasnotthefirstofthewar-builtmerchantfleettofractureinthiswaytherehadbeentenothermajorincidents,andseveralmorewouldfollowbutitwasperha

11、psthemostprominent;itoccurredinfullviewofthecityofPortland,andwaswidelyreportedinthenewspapersevenunderwartimeconditions.Alan Arnold GriffithAlan Arnold GriffithAlan Arnold Griffith(13June(13June189313Oct1963)wasan189313Oct1963)wasanEnglishEnglishengineer,who,amongengineer,who,amongmanyothercontribu

12、tions,ismanyothercontributions,isbestknownforhisworkonbestknownforhisworkonstressstressandandfracturefractureinmetalsinmetalsthatisnowknownasthatisnowknownasmetalmetalfatiguefatigue,aswellasbeingone,aswellasbeingoneofthefirsttodevelopastrongofthefirsttodevelopastrongtheoreticalbasisforthetheoretical

13、basisforthejetjetengineengine.Hetookafirstin.Hetookafirstinmechanicalengineering,mechanicalengineering,followedbyaMastersfollowedbyaMastersDegreeandaDoctoratefromDegreeandaDoctoratefromLiverpoolUniversityLiverpoolUniversity.Alan Arnold Griffith格氏1893年出生于伦敦，1911年毕业于曼岛的一所中学，获得奖学金进入利物浦大学读机械工程，1914年以一等成

14、绩获得学士学位，并获得最高奖章。1915年，格氏到皇家航空研究中心工作，并与G.I.Taylor一起发表了用肥皂膜研究应力分布的开创性论文，该文获得机械工程协会的金奖。同年，格氏获得利物浦大学工程硕士学位。1921年，格氏以他的断裂力学成名作获得利物浦大学工程博士学位。其后，格氏历任空军实验室首席科学家，航空研究中心工程部主管等职，在航空发动机设计方面做出了同样卓越的贡献，与他在断裂方面的名望相比，这些成就就少为人知了。格氏于1939年加盟劳斯莱思公司，1941年当选皇家学会院士，1960年退休，1963年辞世，享年70岁Alan Arnold Griffithl lIn1915hewasac

15、ceptedbytheIn1915hewasacceptedbytheRoyalAircraftFactoryRoyalAircraftFactory asatrainee,beforejoiningthePhysicsandInstrumentasatrainee,beforejoiningthePhysicsandInstrumentDepartmentthefollowingyearinwhatwasnowbeenDepartmentthefollowingyearinwhatwasnowbeenrenamedastherenamedastheRoyalAircraftEstablish

16、mentRoyalAircraftEstablishment(RAE).(RAE).l lSomeofGriffithsearlierworksremaininwidespreadSomeofGriffithsearlierworksremaininwidespreadusetoday.In1917heandusetoday.In1917heandG.I.TaylorG.I.Taylorsuggestedthesuggestedtheuseofsoapfilmsasawayofstudyingstressuseofsoapfilmsasawayofstudyingstressproblems.

17、Usingthismethodasoapbubbleisproblems.Usingthismethodasoapbubbleisstretchedoutbetweenseveralstringsrepresentingthestretchedoutbetweenseveralstringsrepresentingtheedgesoftheobjectunderstudy,andthecolorationofedgesoftheobjectunderstudy,andthecolorationofthefilmshowsthepatternsofstress.Thismethod,thefil

18、mshowsthepatternsofstress.Thismethod,andsimilarones,wereusedwellintothe1990swhenandsimilarones,wereusedwellintothe1990swhencomputerpowerbecamegenerallyavailablethatcomputerpowerbecamegenerallyavailablethatcoulddothesameexperimentnumerically.coulddothesameexperimentnumerically.Alan Arnold GriffithThe

19、work,publishedin1920(Thework,publishedin1920(ThephenomenonofThephenomenonofruptureandflowinsolidsruptureandflowinsolids),resultedinsweeping),resultedinsweepingchangesinmanyindustries.Suddenlythehardeningofchangesinmanyindustries.Suddenlythehardeningofmaterialsduetoprocessessuchasmaterialsduetoproces

20、sessuchascoldrollingcoldrollingwerenowerenolongermysterious.Aircraftdesignersimmediatelylongermysterious.Aircraftdesignersimmediatelyunderstoodwhytheirdesignshadfailedeventhoughunderstoodwhytheirdesignshadfailedeventhoughtheywerebuiltmuchstrongerthanwasthoughttheywerebuiltmuchstrongerthanwasthoughtn

21、ecessaryatthetime,andsoonturnedtopolishingtheirnecessaryatthetime,andsoonturnedtopolishingtheirmetalsinordertoremovecracks.Theresultwasametalsinordertoremovecracks.Theresultwasaseriesofparticularlybeautifuldesignsinthe1930s,suchseriesofparticularlybeautifuldesignsinthe1930s,suchastheastheBoeing247Bo

22、eing247.Thisworkwaslatergeneralizedby.ThisworkwaslatergeneralizedbyG.R.IrwinG.R.Irwin,inthe1950s,applyingittoalmostall,inthe1950s,applyingittoalmostallmaterials,notjustrigidones.materials,notjustrigidones.Alan Arnold GriffithThetheorywasconsideredtoapplyonlytoalimitedclassofextremely,suchasglassesor

23、ceramicsGriffiththeory-1920l lInabodyofaglasscrackspre-exist.Inabodyofaglasscrackspre-exist.l lThetipofsuchacrackconcentratesstress.Thetipofsuchacrackconcentratesstress.l lTheintensestressbreaksatomicbondsonebyTheintensestressbreaksatomicbondsonebyone,likeopeningazipper.one,likeopeningazipper.l lAst

24、hecrackadvances,freshsurfacesareAsthecrackadvances,freshsurfacesarecreated.Thesurfaceenergyincreases,butthecreated.Thesurfaceenergyincreases,buttheelasticenergydecreases.elasticenergydecreases.l lThecrackadvancesiftheadvancereducestheThecrackadvancesiftheadvancereducesthesumofthesurfaceenergyandelas

25、ticenergy.sumofthesurfaceenergyandelasticenergy.Alan Arnold GriffithFromthisworkGriffithformulatedhisowntheoryofFromthisworkGriffithformulatedhisowntheoryofbrittlefracture,usingelasticbrittlefracture,usingelasticstrainenergystrainenergyconcepts.concepts.Histheorydescribedthebehaviorofcrackpropagatio

26、nHistheorydescribedthebehaviorofcrackpropagationofanellipticalnaturebyconsideringtheenergyofanellipticalnaturebyconsideringtheenergyinvolved.Theequationbasicallystatesthatwhenainvolved.Theequationbasicallystatesthatwhenacrackisabletopropagateenoughtofractureacrackisabletopropagateenoughtofractureama

27、terial,thatthegaininthesurfaceenergyisequaltomaterial,thatthegaininthesurfaceenergyisequaltothelossofstrainenergy,andisconsideredtobethethelossofstrainenergy,andisconsideredtobetheprimaryequationtodescribebrittlefracture.Becauseprimaryequationtodescribebrittlefracture.Becausethestrainenergyreleasedi

28、sdirectlyproportionaltothestrainenergyreleasedisdirectlyproportionaltothesquareofthecracklength,itisonlywhenthethesquareofthecracklength,itisonlywhenthecrackisrelativelyshortthatitsenergyrequirementforcrackisrelativelyshortthatitsenergyrequirementforpropagationexceedsthestrainenergyavailabletoit.pro

29、pagationexceedsthestrainenergyavailabletoit.BeyondthecriticalGriffithcracklength,thecrackBeyondthecriticalGriffithcracklength,thecrackbecomesdangerous.becomesdangerous.Alan Arnold Griffithl lGriffithismorefamousforatheoreticalstudyontheGriffithismorefamousforatheoreticalstudyonthenatureofstressandfa

30、ilureinmetals.Atthetimeitnatureofstressandfailureinmetals.AtthetimeitwasgenerallytakenthatthestrengthofamaterialwaswasgenerallytakenthatthestrengthofamaterialwasE/10,whereEwastheE/10,whereEwastheYoungsmodulusYoungsmodulusforthatforthatmaterial.Howeveritwaswellknownthatthosematerial.Howeveritwaswellk

31、nownthatthosematerialswouldoftenfailat1000timeslessthanthismaterialswouldoftenfailat1000timeslessthanthispredictedvalue.Griffithdiscoveredthattherewerepredictedvalue.Griffithdiscoveredthatthereweremanymicroscopiccracksineverymaterial,andmanymicroscopiccracksineverymaterial,andhypothesizedthatthesecr

32、acksloweredtheoverallhypothesizedthatthesecracksloweredtheoverallstrengthofthematerial.Thiswasbecauseanyvoidinstrengthofthematerial.Thiswasbecauseanyvoidinasolidconcentratesstress,afactalreadywellknownasolidconcentratesstress,afactalreadywellknowntomachinistsatthetime.Thisconcentrationwouldtomachini

33、stsatthetime.ThisconcentrationwouldallowthestresstoreachE/10attheheadofthecrackallowthestresstoreachE/10attheheadofthecracklongbeforeitwouldseemtoforthematerialasalongbeforeitwouldseemtoforthematerialasawhole.whole.thefatherofFractureMechanicsDr.Dr.George Rankin IrwinGeorge Rankin Irwin(February26,1

34、907(February26,1907October9,1998)wasanOctober9,1998)wasanAmericanAmericanscientistinthescientistinthefieldoffieldoffracturefracturemechanicsmechanicsandandstrengthstrengthofmaterialsofmaterials.Hewas.Hewasinternationallyknownforinternationallyknownforhisstudyoffractureofhisstudyoffractureofmaterials

35、materialsGeorge Rankin Irwinl lGeorgeR.IrwinwasborninGeorgeR.IrwinwasborninElPaso,TexasElPaso,Texas.His.HisfamilymovedtofamilymovedtoSpringfieldSpringfield,IllinoisIllinoiswherehewenttowherehewenttoschool.school.l lHeattendedHeattendedKnoxCollegeKnoxCollegeininGalesburgGalesburg,IllinoisIllinoisanda

36、ndearnedanA.B.degreeinEnglishin1930.AfteranearnedanA.B.degreeinEnglishin1930.Afteranadditionalyearstudyingphysics(getadditionalyearstudyingphysics(getbachelorsdegreeinphysicsat1931)lAnelderbrother,William,hadstudiedengineeringattheUniversityofIllinois(latertobeVice-PresidentoftheSpringfieldBoilerCo.

37、),sothatGRIwasknownthere,andwasinvitedaftergraduationatKnoxtofillagraduateassistantteachingpostattheUniversityofIllinois,whichheaccepted.George Rankin IrwinlItpermittedhimtoacquirehismastersdegreein1933,andsubsequentlyaPhDinphysicsin1937.Meanwhile,auniqueeventinGeorgeslifeoccurredin1933,withmarriage

38、toGeorgiaBoyntonShearer,creatingastrongpartnershipthatwastolastfor65years.lAMemberoftheAmericanNationalAcademyofEngineering,RoyalSocietyofLondon,anHonoraryMemberandwinnerofprizesandawardsofmanyAmericanandEuropeanscientificsocieties.l1986TimoshenkoMedal George Rankin Irwinl lGRIrwin,FractureDynamics,

39、FracturingofMetals,AmericanSocietyforMetals,1948,p147166l lGRIrwinAnalysisofstressesandstrainsneartheendofacracktraversingaplate.J.Appl.Mech.1957,24(3),361364.lDiscussion,J.Appl.Mech.,25,No.2,299-303(1958).George Rankin Irwinl lIrwindefinedthefundamentalconceptofaIrwindefinedthefundamentalconceptofa

40、Stress Intensity FactorStress Intensity Factorandthecriticalstressandthecriticalstressintensityfactor(KIC)whichisaintensityfactor(KIC)whichisamaterialmaterialpropertyproperty.lHisideasveryimportantforpracticaluseandsubsequentworksdevotedtotheirimprovementanddevelopmentcausedadecisiveinfluenceonthepr

41、ogressinfracturemechanicsasanewscienceandpowerfulengineeringtoolapplicabletonumerousproblemsconnectedwithmanufacturingandprocessingofmaterialsandtheirfailureproofoperationincriticalstructuresofvariousmaterials.EOrowan1949 Rep.Prog.Phys.12 185-232wasborninObuda,apartofBudapestCourtesyofMITMuseumTheX-

42、raystudiesconductedearlierbyOrowan(1955)showedthateveninmaterialsfracturinginapurelybrittlemanner,therewasevidenceofextensiveplasticdeformationonthecracksurfaces.EOrowanFellowoftheRoyalSociety,(1947)MemberoftheAmericanAcademyofArtsandSciences,(1951)MemberoftheNationalAcademyofSciences,(1969);Bingham

43、MedaloftheAmericanSocietyofRheology,(1959);GaussMedaloftheBraunschweigerWissenschaftlicheGesellschaft,(1968);VincentBendixGoldMedaloftheAmericanSocietyforEngineeringEducation,(1971);PaulBergseMedaloftheDanishMetallurgicalSociety,(1973);TheActa MetallurgicaGoldMedal,(1985).l lGCSih(薛昌明)MechanicsofFra

44、cture.Leyden:NoordhoffInternationalPublishing,1973-1979共六卷l lHTada,PCParis,andGRIrwinThestressAnalysisofCracksHandbook.St.Louis:ParisProductionsInc.,19853rdedition2000标志着线弹性断裂力学趋于成熟Othercontributionl lPaulParisPaulParisindevelopingmethodsforpredictingcrackindevelopingmethodsforpredictingcrackgrowtha

45、nditscontrolinaircraftstructures;growthanditscontrolinaircraftstructures;l lF.ErdoganF.Erdoganoncracksinthin-walledshellstructures;oncracksinthin-walledshellstructures;l l A.A.WellsA.A.Wellsoftheoncharacterizingfractureinnormallyoftheoncharacterizingfractureinnormallyductilesteelstructures;ductilest

46、eelstructures;l lF.A.McClintockF.A.McClintock,MassachusettsInstituteofTechnology,MassachusettsInstituteofTechnologyandandJohnW.HutchinsonJohnW.Hutchinson,HarvardUniversity,onthe,HarvardUniversity,onthedevelopmentoffracturemechanicsproceduresinthedevelopmentoffracturemechanicsproceduresinthepresenceo

47、fsubstantialductility;presenceofsubstantialductility;l lJamesR.RiceJamesR.Rice,HarvardUniversity,ondevelopingtheJ,HarvardUniversity,ondevelopingtheJintegralapproachforcharacterizingtheonsetofcrackintegralapproachforcharacterizingtheonsetofcrackgrowthinductilematerials;growthinductilematerials;l lL.B

48、.FreundL.B.Freund,BrownUniversity,and,Southwest,BrownUniversity,and,SouthwestResearchInstitute,onthedynamicsofinertiallimitedResearchInstitute,onthedynamicsofinertiallimitedcrackpropagationandarrestcrackpropagationandarrest国内我国断裂力学工作起步至少比国外晚了20年，直到上世纪70年代，断裂力学才广泛引入我国，一些单位和科技工作者逐步开展了断裂力学的研究和应用工作。Disa

49、sterexamples蒸压釜发生爆炸l l20102010年年1111月月7 7号号凌晨1点45分左右l l上海建华管桩有限公司车间内一个蒸压釜发生爆炸上海建华管桩有限公司车间内一个蒸压釜发生爆炸5名工人不同程度受伤。原定恒压0.92兆帕。当压力值还在0.7至0.8兆帕时，容器突然爆炸，釜门连接处断裂。2吨多重的釜门受巨大冲击力作用，瞬间飞过围墙。塔吊断裂l l2008年8月6号呼和浩特市敕勒川大街与腾飞路交汇处的金隅时代城施工现场发生塔吊断裂事故钢缆吊杆l l2001年11月8号l l此次事故是连接拱体和桥面预制板的4对8根钢缆吊杆断裂，北端长约10米、南端长20余米的桥面预制板发生坍塌。

50、l l四川宜宾南门大桥断裂事故“过山车”半轴断裂l l2003年8月31日重庆游乐园“过山车”半轴断裂事故图说明：过山车最后停车点;半轴断裂段及撞伤轨道点共7条横档及右侧轨道变形处;撞断脱件飞出砸伤雷车停车港防雨棚;半轴断裂后被撞伤轨道的第二段共14条横档;过山车始发车站台。半轴的断裂属于疲劳断裂管道断裂l l2009年3月23日云南省水富县，云南云天化股份有限公司合成氨装置合成塔出口管道断裂事故受伤人数至17人。起重机断裂l l20082008年年3 3月月1515日，日，纽约曼哈顿中城东侧纽约曼哈顿中城东侧一处建筑工地的起重一处建筑工地的起重机断裂，砸到附近建机断裂，砸到附近建筑物，造成筑

51、物，造成4 4人死亡，人死亡，多人受伤。有报道说，多人受伤。有报道说，事故可能是由于一个事故可能是由于一个钢块坠落，切断了固钢块坠落，切断了固定起重机塔体的一根定起重机塔体的一根缆绳引起的缆绳引起的 飞机l l2010年7月27日德国汉莎航空一架MD-11货机在沙特首都利雅得的哈立德国王国际机场坠毁吊桥断裂l l20092009年年4 4月月1313日秘鲁吊桥断裂事故日秘鲁吊桥断裂事故 l l秘鲁南部阿亚库乔省科拉科拉县日发生一起秘鲁南部阿亚库乔省科拉科拉县日发生一起严重的吊桥断裂事故，造成至少严重的吊桥断裂事故，造成至少7 7名学生、名学生、2 2名名老师、人受重伤。老师、人受重伤。据当地媒

52、体报道，当天下据当地媒体报道，当天下午，科拉科拉县一所学校午，科拉科拉县一所学校的多名师生放学后从的多名师生放学后从一座吊桥上走过时，吊桥一座吊桥上走过时，吊桥突然从中间断裂，桥上的突然从中间断裂，桥上的师生几乎都摔入距离桥面师生几乎都摔入距离桥面约米的河中约米的河中Cleveland East Ohio Gas explosionl lCleveland East Ohio Gas ExplosionCleveland East Ohio Gas ExplosionoccurredoccurredontheafternoonofFriday,October20,1944.ontheafter

53、noonofFriday,October20,1944.Theresultinggasleak,explosionandfireskilledTheresultinggasleak,explosionandfireskilled130peopleanddestroyedaonesquaremile130peopleanddestroyedaonesquaremileareaonCleveland,Ohioseastside.areaonCleveland,Ohioseastside.ArielviewofdamagefromEastOhioGasExplosionSanFranciscoOak

54、landBayBridgeOct.27,2009-Dec.22,2009OilspillofGulfofMexicol lTheDeepwaterHorizondrillingrigcollapsedintheGulfofMexicoonApril22,2010TitanicAt2:20a.m.,April15,1912,theTitanicsankwiththelossofmorethan1,500lives.AmetallurgicalanalysisofsteeltakenfromthehulloftheTitanicswreckagerevealsthatithadahighducti

55、le-brittletransitiontemperature,makingitunsuitableforserviceatlowtemperatures;atthetimeofthecollision,thetemperatureoftheseawaterwas-2C.Theanalysisalsoshows,however,thatthesteelusedwasprobablythebestplaincarbonshipplateavailableatthetimeoftheshipsconstruction.Boston Molasses Disaster-January15,1919l

56、CylinderstressfailureDamagetotheBostonElevatedRailwayduetothefloodBoston Molasses Disaster-January15,1919amolassestank15mtall,27mindiameterandcontainingasmuchas2,300,000USgal(8,700m3)collapsed.Witnessesstatedthatasitcollapsed,therewasaloudrumblingsound,likeamachinegunastherivetsshotoutofthetank,andt

57、hatthegroundshookasifatrainwerepassingby.Thecollapseunleashedawaveofmolasses25feet(7.6m)highatitspeak,movingat35milesperhour(56km/h).ThemolasseswavewasofsufficientforcetodamagethegirdersoftheadjacentBostonElevatedRailwaysAtlanticAvenuestructureandtiparailroadcarmomentarilyoffthetracks.AuthorStephenP

58、uleodescribeshownearbybuildingsweresweptofftheirfoundationsandcrushed.Severalblockswerefloodedtoadepthof2to3feet(60to90cm).PuleoquotesaBoston Postreport:TheSilver Bridgewasaneyebar-chainsuspensionbridgebuiltin1928andnamedforthecolorofitsaluminumpaint.ThebridgeconnectedPointPleasant,WestVirginiaandGa

59、llipolis,Ohio,overtheOhioRiver.OnDecember15,1967,theSilverBridgecollapsedwhileitwasfullofrush-hourtraffic,resultinginthedeathsof46people.Twoofthevictimswereneverfound.ThecollapsedSilverBridge,asseenfromtheOhiosideThebridgefailurewasduetoadefectinasinglelink,eyebar330,onthenorthoftheOhiosubsidiarycha

60、in,thefirstlinkbelowthetopoftheOhiotower.Asmallcrackwasformedthroughfrettingwearatthebearing,andgrewthroughinternalcorrosion,aproblemknownasstresscorrosioncracking.Thecrackwasonlyabout0.1inch(2.5mm)deepwhenitwentcritical,anditbrokeinabrittlefashion.Growthofthecrackwasprobablyexacerbatedbyresidualstr

61、essintheeyebarcreatedduringmanufacture.Whenthelowersideoftheeyebarfailed,alltheloadwastransferredtotheothersideoftheeyebar,whichthenfailedbyductileoverload.Thejointwasthenheldtogetheronlybythreeeyebars,andanotherslippedoffthepinatthecenterofthebearing,sothechainwascompletelysevered.Collapseoftheenti

62、restructurewasinevitablesinceallpartsofasuspensionbridgeareinequilibriumwithoneanother.Witnessesafterwardestimatedthatittookonlyaboutaminuteforthewholebridgetofall.King Street Bridge(Melbourne)OverlookingtheKingStreetBridgeandCrownCasinoandEntertainmentComplexThebridgewasdesignedin1959byUtahAustrali

63、afortheCountryRoadsBoard,andconstructedoverthenexttwoyears,beingopenedon12April1961.Itwasofawelded,deck-girder,suspended-spanconstructionwithspansupto160feet(49m)long.King Street Bridge(Melbourne)Soonaftercompletion,on10July1962,onespancollapsedundertheweightofa47tonsemi-trailer,thoughtheweightwaswi

64、thinthebridgelimits.ThesubsequentRoyalCommissionfoundthatbridgefailedwithabrittlefractureonaverycoldMelbournewinterday.TheCommissionidentifiedthecauseofgirderfailurewasduetocrackedwelds.King Street Bridge(Melbourne)Thefabricatorwasnotfamiliarwithweldinglow-alloysteelandthesteelsuppliedwashighincarbo

65、nmakingitdifficultevenforanexperiencedfabricator.ThecracksintheweldswerenotdiscoveredbyinspectorsofboththefabricatorandtheCountryRoadsBoard.Thesouthendofthebridgehasbeenundergoingdifferentialsettlementbetweentheapproachrampsrestingonfill,andthesuspendedsectionsupportedbyboredpiles.Theembarrassinginc

66、identwaswidelysatirisedatthetime;mostnotablybytheMelbourneTVclownsZigandZagandwastheinspirationforaSpikeMilliganradiocomedy.Structural Failure of Alohas 73728April1988causedbyfatiguefailureOtherexamplesFracturedleginplastercastCrackedconcreteDriedGroundDriedGroundExamplesl lDrymudtexturebulletholex-rayshowingfemurfracturefromautoaccidentWintericelayerl l美国硅谷埃及博物馆盛装人木乃伊的棺材1943-47年,美国近500艘全焊船1000多起脆性破坏，238艘报废。总是在焊接缺陷等应力集中区域，-34C水1947年，苏联4500m3石油储罐，-43C，底部和下部壳连接处，大量裂纹。（低温、脆性、焊点应力集中、内外温差）五十年代，美国北极星导