简介:Onthebasesofhightemperaturecreepexperiments,theresearchonengineeringapplicationofrheologicalformingiscarriedoutontwokindsoflightmetalalloypartsnamedcylindricalshellofLc4aluminumalloyandvanediskwithcomplexcurvedsurfaceofTC11titaniumalloy.Moreover,themechanicalpropertytestsunderroomandhightemperaturesfortheworkpiecesproducedbythisnewtechniquearealsodone,theresultsshowedthattheyaremuchimprovedevidentlycomparedwiththoseproducedbytraditionalmethod.
简介:AnumericalanalysiswascarriedouttostudythemovingboundaryprobleminthephysicalprocessofpulsedNd-YAGlasersurfacemeltingpriortovaporization.Theenthalpymethodwasappliedtosolvethistwo-phaseaxisymmetricalmehingproblem.Computationalresultsoftemperaturefieldswereobtained,whichprovideusefulinformationtopracticallairtreatmentprocessing.Thevalidityofenthalpymethodinsolvingsuchproblemsispresented.
简介:Thispaperappliesthestochasticfiniteelementmethodtoanalysethestatisticsofstressesinearthdamsandassessthesafetyandreliabilityofthedams.Formulationsofthestochasticfiniteelementmethodarebrieflyreviewedandtheprocedureforassessingdam’sstrengthandstabilityisdescribed.Asanexample,adetailedanalysisforanactualdam-Nululindamisperformed.Apracticalmethodforstudyingbuilt-damsbasedontheprototypeobservationdataisdescribed.
简介:Inthispaperthedualreciprocityboundaryelementmethodisemployedtosolvenonlineardifferentialequation~2u+u+εu~3=b.ResultsobtainedinanexamplehaveagoodagreementwiththosebyFEMandshowtheapplicabilityandsimplicityofdualreciprocitymethod(DRM)insolvingnonlineardif-ferentialequations.
简介:Stress-dependenceoftheintrinsictimeofviscoelasticmaterialsisinvestigated.Theinfluenceofstresslevelontheintrinsictimeisconsideredtobesimilartothatoflemperature,pressure,solventcon-centration,damageandphysicalaging.Thetime-lemperature-stressequivalenceprincipleisproposed,byemployingwhich,thecreepcurvesatdifferenttemperaturesandstresslevelscanbeshiftedintoamastercurveatreferencetemperatureandstresslevel.Thusthelong-termcreepbehaviorofviscoelasticmaterialsatalowertemperatureandstresscanbepredictedfromtheshort-termoneatahighertemperatureandstress.Asanexample,thenonlinearcreepbehaviorofhigh-densitypolyethylene(HDPE)atroomtemperatureisstudiedusingthetime-temperature-stressequivalenceprinciplepresented.
简介:Basedonthethermodynamictheory,anorthotropicdamageconstitutivemodelwasdevelopedtodescribethenonlinearmechanicalbehaviorofC/SiCcomposites.Thediferentnonlinearkinematicandisotropichardeningfunctionswereadoptedtodescribeaccuratelythedamageevolutionprocesses.Thedamagevariablesweredefinedwiththedamagedmodulusandtheinitialundamagedmodulusonenergyequivalenceprinciple.Theinitialorthotropyanddamagecouplingwerepresentedinthedamageyieldfunction.Tensileandin-planeshearloadingandunloadingtestswereperformed,andagoodagreementbetweenthemodelandtheexperimentalresultswasachieved.
简介:Animprovedmodelforultrasonictransducersisproposed.Byconsideringonlythefirstsymmetricmode,eachlayerisrepresentedasanacousticaltransmissionlineinmodelingofbulkwavetransducers.Inimagingapplications,widebandwidthandshorttimedurationarerequired.Theapproachwehaveusedconsistsofimpedancematchingthefrontfaceofthepiezoelectrictransducertothepropagatingmediumwithaquarterwavelengthimpedancematchinglayerandinsertinganunmatchingquarterwavelengthacousticallayerbetweentherearfaceandbackingmaterial.Aheavybackingwoulddegradethewide-bandphenomena,butshowatimedurationshorterthan0.5μsforimagingapplications.PSPICEcodeofthecontrolledsourcemodelisimplementedtopreciselypredicttheperformanceofthematchedtransducerssuchasimpedance,insertionloss,bandwidthanddurationoftheimpulseresponse.Goodagreementbetweenthesimulationandexperimentalresultshasbeenachieved.
简介:Applyingtheparametricderivationmethod,PeierlsenergyandPeierlsstressarecalculatedwithanon-sinusoidalforcelawinthelatticetheory,whiletheresultsobtainedbythepower-seriesexpansionaccordingtosinusoidallawcanbededucedasalimitingcaseofnon-sinusoidallaw.ThesimplifiedexpressionsofPeierlsenergyandPeierlsstressareobtainedforthelimitofwideandnarrow.PeierlsenergyandPeierlsstressdecreasemonotonicallywiththefactorofmodificationofforcelaw.PresentresultscanbeusedexpedientlyforpredictionofthecorrectorderofmagnitudeofPeierlsstressformaterials.
简介:Anapproachbasedoncontinuumdamagemechanicstofatiguelifepredictionforstructuresisproposed.Anewfatiguedamageevolutionequationisdeveloped,inwhichtheparametersareobtainedinasimplewaywithreferencetotheexperimentalresultsoffatiguetestsonstandardspecimens.WiththeutilizationofAPDLlanguageontheANSYSplatform,afiniteelementimplementationispresentedtoperformcouplingoperationondamageevolutionofmaterialandstressredistribution.ThefatiguelivesofsomenotchedspecimensandaPitch-change-linkarepredictedbyusingtheaboveapproach.Thecalculatedresultsarevalidatedwithexperimentaldata.
简介:一个代理人联合为技术和粒子群优化建模的代理人的基于的粒子群优化(SBPSO)算法被用于合成压力容器的基于可靠性的柔韧的设计(RBRD)。SBPSO的算法和效率通过数字例子被显示。为细丝创伤的一个模型有金属性的班机的合成压力容器然后被网分析学习,它的回答被使用有限元素方法分析(由软件ANSYS表现了)。为最大化性能因素的一个优化问题被在圆柱的部分,金属班机的厚度和dropoff区域尺寸选择螺旋状的厚度的弯屈的取向为设计变量提出。为合成的层和金属班机的力量限制被分别地使用Tsai-Wu失败标准和协定失败标准构造。方法建议了的数字例子表演能有效地解决RBRD问题,和建议模型的最佳的结果能满足某些可靠性要求并且有坚韧性到设计变量的变化。
简介:‘Stent对stent’研究是被设计与以前同意的相比显示出新stent图案的优势的一种使随机化的试用。这些研究被规章的机构通常使用,例如美国食物药品管理局(食物及药品管理局),到表示同意到新stent图案。有这些临床的试用的问题是他们的高费用和困难。在这份报纸,为‘stent对stent’的一种数字选择复杂临床的研究被介绍。一个有限元素模型被开发在冠的stent放置以后在结果上调查stent设计的影响。二商业地可得到的stents(NIR和多连接stents)被建模,他们的行为以压力分发在推广期间被比较,光线的获得,外部直径变化并且节略。而且,狭窄率上的stent设计的效果被在动脉以内比较压力分发调查。在stented动脉的动脉的墙压力的分析显示多连接stent设计原因与slotted试管NIR设计相比与局部性的stenotic损害降低应力到一个动脉粥样硬化患者容器。有观察临床的狭窄的调查结果相互关联与多连接stent设计相比在NIR评估狭窄率,它更高报导了。