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简介：ThistalkwillsummarizetherecentworkrelatedtoakindofnewnanomaterialsproducedbytheSMAT(surfacemechanicalattritiontreatment).Theconceptofsurfacenanocrystallizationofmaterialswillbepresented.Intermsofthegrainrefinementmechanisminducedbyplasticdeformation,anovelsurfacemechanicalattrition(SMA)techniquewasdevelopedforsynthesizingananostructuredsurfacelayeronmetallicmaterialsinordertoupgradetheoverallpropertiesandperformance.ThegrainrefinementmechanismofthesurfacelayerduringtheSMAtreatmentwillbeanalyzedintermsofthenanostructureobservationsinseveraltypicalmaterials.Veryhighyieldstress(5timesofthebasematerial)onthesurfacelayerofthematerialobtainedbytheSMAThasbeenobserved.Theeffectofsurfacenanostructuresonthemechanicalbehaviorandonthefailuremechanismofmetallicmaterialshowsthepossibilitytodevelopanewstrengthgradientcompositeusingco-rollingandnitriding.Theroleofresidualstressinducedduringthetreatmentwillbeinvestigatedanddiscussed.Thedevelopedmaterialsarealsoporosityfreematerialswhichcanbeusedasreferencematerialforthelocalmechanicalbehaviorinvestigationtechniquesuchasthenanoindentation.Ageneralconceptforobtaininghighstrengthandhighductilitynanostructuredmaterialswillbepresented.Theexceptionalhighstrengthandhighductilitysteelshavedeveloped.Thesimulationofthemechanismsforimprovingductilityofhighstrengthnanostructuredmaterialswillbepresented.Thepotentialapplicationsforthelandtransportationvehicles(car,bus,train)andwindenergyhavebeeninvestigated.Someexamplesofconceptdesignfortheintegrationoftheadvancednanostructuredsteelswillbepresented.

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简介：selectingseveraltypicalDSS00Cr22Ni5Mo3N,00Cr21Ni2Mn5Nand00Cr25Ni7Mo4Nasresearchmaterials,hotductilitycharacteristicofDSSwasstudiedandmicrostructureevolutionduringhotcompressionwasobserved.TheresultsshowthattheoptimumhotductilitytemperaturerangeofDSSis1050~1200℃.00Cr25Ni7Mc4Nexhibitstheworsthotductilityand00Cr21Ni2Mn5Nhassimilarhotductilityto00Cr22Ni5Mo3N.Duringhotcompression,austeniteofDSSmainlyoccursdynamicrecovery,theferriteof00Cr22Ni5Mo3N,00Cr21Ni2Mn5Ncanperformdynamicrecoveryandrecrystallization,butonlydynamicrecoverycanbeobservedintheferriteof00Cr25Ni7Mo4N.

简介：Accurateestimatesofductilitydemandsonbuckling-restrainedbracedframes(BRBFs)arecrucialtoperformance-baseddesignofBRBFs.AnanalyticalstudyontheseismicbehaviorofBRBFshasbeenconductedattheATLSSCenter,LehighUniversitytoprepareforanupcomingexperimentalprogram.TheanalysisprogramDRAIN-2DXwasusedtomodelaone-bay,four-storyprototypeBRBFincludingmaterialandgeometricnonlinearities.Thebucklingrestrainedbrace(BRB)modelincorporatesbothisotropicandkinematichardening.NonlinearstaticpushoverandtimehistoryanalyseswereperformedontheprototypeBRBF.PerformanceobjectivesfortheBRBsweredefinedanduscdtoevaluatethctime-historyanalysisresults.ParticularemphasiswasplacedonglobalductilitydemandsandductilitydemandsoatheBRBs.Thesedemandswerecomparedwithanticipatedductilitycapacities.Theanalysisresults,alongwithresultsfromsimilarpreviousstudics,areusedtoevaluatetheBRBFdesignprovisionsthathavebeenrecommendedforcodificationintheUnitedStates.ThcresultsshowthatBRBmaximumductilitydemandscanbeashighas20to25.ThesedemandssignificantlyexceedthoseanticipatedbytheBRBFrecommendedprovisions.Resultsfromthestaticpushoverandtimehistoryanalysesareusedtodemonstratewhytheductilitydemandsexceedthoseanticipatedbytherecommendedprovisions.TheBRBqualificationtestingprotocolcontainedintheBRBFrecommendedprovisionsisshowntobeinadequatebecauseitrequiresonlyamaximumductilitydemandofatmost7.5.Modificationstothetestingprotocolarerecommended.

简介：在这篇论文，韧性剧降裂开(DDC)在不同压力状态下面的在Inconel600同伴Filler金属82的危险性(FM82)被调查。Inconel600是有到一般腐蚀，局部性的腐蚀，和压力腐蚀的优秀抵抗的Ni-Cr-Fe合金，它广泛地尽最大努力被使用了植物。然而，同伴FM82被显示了产生在焊接过程的DDC。解决这个问题，这个工作主要集中于在焊接过程在FM82评估DDC危险性。首先，到破裂(STF)测试的紧张被用来在简单压力状态下面完成DDC标准，并且DDC的形成机制被解释。真实焊接是有复杂压力状态的一个过程。后来，强调状态在建筑群下面得到DDC危险性，关于焊接的多传递的模型借助于有限元素方法被建立。根据数字模拟结果，变丑和温度历史的关系被完成。而且，易受影响的地点和时刻能被决定把结果与STF联系了。模拟结果相当适合从另一研究焊接实验。

简介：ThehotductilityofFe-36NiinvaralloywithdifferentadditionsoftheelementceriumwasinvestigatedusingaGleeble-3800thermal-mechanicalsimulatoroverthetemperaturerange850-1050℃,andtheimprovementmechanismofthehotductilitywasanalyzedusingacombinationofSEM,EDS,andOM.TheresultsindicatedthatFe-36Niinvaralloyexhibitedpoorhotductilitybelow1050℃,whichwasmainlyattributedtoweakgrainboundariesandtheactionofgrainboundarysliding.However,thealloyswithceriumcontentsof0.016%and0.024%bothdemonstratedsubstantialimprovementinthehotductilityovertheentiretestingtemperaturerange.Theobservedimprovementofthehotductilityofthealloywith0.016%ceriumat950℃andthealloywith0.024%ceriumat900℃wasassociatedmainlywiththegrainboundarystrengtheningandtherestrictionofthegrainboundaryslidingbecausetheadditionofceriumreducedthesegregationofsulfuratgrainboundariesandrefinedthegrainstructure.Theoccurrenceandaccelerationofdynamicrecrystallizationwerefoundtoberesponsibleforthehighhotductilityofthealloywith0.016%ceriumat1000℃andthealloywith0.024%ceriumat950-1000℃asaresultoftherefinementofthegrainstructurebyadditionofcerium.

简介：ThenanostructuredAl-basedcompositespossessthecombinationofhighyieldstrengthandgoodductility.Inthispaper,amicromechanicalmodelispresentedtosimulatethemechanicalresponseofbimodalnanostructuredAlandtheparticle-reinforcedaluminummatrixcomposite(PAMC).Theconstitutiverelationsfordifferentphasesareaddressedinthemodel,aswellasthecontributionofmicrocracks.NumericalresultsshowthatthemodelcansuccessfullydescribetheenhancedstrengthandductilityofthebimodalnanostructuredAl,andthepredictionsofthePAMCareingoodagreementwiththeexperimentaldata.ItisworthnotingthatthestrengthandductilityaresensitivetothevolumefractionofconstituentsandthedistributionofmicrocracksinbothbimodalnanostructuredAlandPAMC.Therefore,thepresenttheoreticalresultscanbeusedtooptimizethemicrostructureforimprovingthemechanicalpropertiesofnanostructuredAl-basedcomposites.

简介：基于表演的地震工程是由于它写实地模仿结构的反应特征的能力导致了广泛地发达的设计方法论的研究的一个最近的焦点。地震要求的精确预言是基于表演的设计方法论的一个关键部件。这篇论文与中等韧性论述增强的具体时刻框架的地震需求评估。利用简化非线性的静态的分析的精确性被比较在很多个框架上对时间历史分析的结果估计。排水量侧面，飘移需求和最大的塑料旋转被计算估计地震要求。估计的地震要求与在FEMA356的接受标准相比。结果显示这些框架有足够的能力抵抗比限制价值大的interstory飘移。

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简介：过去常在在当前的地震代码采用的基于力量的设计过程决定力量减小因素的最重要的参数是结构的韧性。为在一个灵活基础上支持的结构，韧性因素能被基础依从影响。在当前的代码给的韧性因素主要被分配忽略这研究的目的是在像栈的结构的韧性因素上估计SSI现象的意义的SSI并且因此的效果。像栈的结构的使变形的配置就非线性的时刻弯曲关系而言作为横梁元素的一个集合被理想化，当一个线性摇摇摆的模型被实现为支持的土壤建模时。用一套人工的记录，重复了线性、非线性的分析被逐渐地在非线性的分析增加加速的紧张到首先在线性、非线性的分析钢让步被观察的水平和相应于栈倒塌的水平执行。无弹性、有弹性的电阻之间的差别以排水量韧性因素被确定了。结果显示基础灵活性能减少系统的韧性并且忽视这现象可以在灵活地支持的R/C像栈的结构的地震表演的预言导致错误的结论。

简介：Becauseoftheexcellentmechanicalpropertiesof34C「NiMo6steel,itiswidelyusedinhigh-valuecomponents.Manyconventionalapproachestostrengthening-steelstypicallyinvolvethelossofusefulductility.Inthisstudy,34CrNiMo6Steelhavinghighstrengthandductilityisproducedbylasersolidforming(LSF)w让haquenching-tempering(QT)treatment.TemperingofbainiteismainlybysolidphasetransformationinthepreviousLSFlayersduringtheLSFprocess.ThestablemicrostructureofLSFconsistsofferriteandfinecarbides.Themicrostructuretransferstotemperedsorbiteafterheat-treatment.ThetensilepropertiesoftheLSFsteelmeetthoseofthewroughtstandard.TheUTSandelongationofLSFsampleat858MPa,19.2%,respectively,aregreaterthanthoseofthewrought.TheQTtreatmentenhancedtheultimatetensilestrengthandyieldstrengthoftheLSFsample.Theultimatetensilestrength,yieldstrength,reductioninarea,andelongationoftheLSF+QTsampleat980MPa,916MPa,58.9%,and13.9%,respectively,aregreaterthanthoseofthewroughtstandard.TheyieldstrengthoftheLSF+QTsampleisapproximately1.27timesthatofthewrought.TheLSFsamplesfailedinaductilefracturemode,whiletheLSF+QTsamplesshowedmixed-modefailure.ThedefectshaveonlyasmalleffectonthetensilepropertiesowingtotheexcellentductilityoftheLSFsample.

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简介：Achievingnotonlyhighmechanicalstrengthsbutalsohighductilityisrecentlyestablishedusinganadditivemanufacturingtechniquecalledselectivelasermelting.Inthepresentstudy,stainlesssteel304Lfullydensesamplesweresuccessfullyprintedusingthe3Dsystems-ProX300printingmachine.TheductilityandtensileyieldstrengthwerealmosttwoandthreetimeshighercomparedtothoseofASTMcast'salloy.Honeycomblikenano-cellularstructurew让hdifferentorientationwasobservedinthefinegrains(-4μm)duetofastcoolingrate.Inadd让ion,theformationofmartensitephaseinrandomgrainsisalsoacontributortothestrengths.Furthermore,negativeresidualstressesinthebuildandhorizonraldirectionsweredetectedandassistedfurtherincreaseinthetensilestrength.Fractographyrevealedtheductilefeatureofplasticdeformationandthecrackopeningsatunmeltedparticlesorpores.

简介：Itisknownthatstructuralstiffnessandstrengthdistributionshaveanimportantroleintheseismicresponseofbuildings.Theeffectofusingdifferentcode-specifiedlateralloadpatternsontheseismicperformanceoffixed-basebuildingshasbeeninvestigatedbyresearchersduringthepasttwodecades.However,noinvestigationhasyetbeencarriedoutforthecaseofsoil-structuresystems.Inthepresentstudy,throughintensiveparametricanalysesof21,600linearandnonlinearMDOFsystemsandconsideringfivedifferentshearstrengthandstiffnessdistributionpatterns,includingthreecode-specifiedpatternsaswellasuniformandconcentricpatternssubjectedtoagroupofearthquakesrecordedonalluviumandsoftsoils,theeffectofstructuralcharacteristicsdistributiononthestrengthdemandandductilityreductionfactorofMDOFfixed-baseandsoil-structuresystemsareparametricallyinvestigated.Theresultsofthisstudyshowthatdependingonthelevelofinelasticity,soilflexibilityandnumberofdegrees-of-freedoms(DOFs),structuralcharacteristicsdistributioncansignificantlyaffectthestrengthdemandandductilityreductionfactorofMDOFsystems.Itisalsofoundthatathighlevelsofinelasticity,theductilityreductionfactoroflow-riseMDOFsoil-structuresystemscouldbesignificantlylessthanthatoffixed-basestructuresandthereductionislesspronouncedasthenumberofstoriesincreases.