简介:Ahumanfacewithcomplex3Dstructureismachinedwithamodifiedfix-lengthcompensationmethodinthispaper.ThefastdevelopmentofMEMS(MicroElectromechanicalSystems)hasstronglyenhancedtheapplicationofnewharderworkmaterials.Asalowcost,flexible,goodrepeatablemachiningprocesswithnegligibleprocessforces,micro-EDMmillingiswellsuitedforfreeformmetallicmicrostructures.Amajorprobleminmicro-EDMmillingofcomplex3Dstructureistheelectrodewear.AnewCAMsystembasedontheUGsoftwareplatformisdevelopedinordertogetgoodaccuracyandhigherefficiency.Acorrectioncoefficientisintroducedanddeducedforthemodifiedfix-lengthcompensationmethod.Usingthismethodahumanfacewithcomplex3Dstricterismachinedsuccessfullybymicro-EDMmilling.
简介:Basedonrigid-plasticfiniteelementmethod,askewrollingprocessofsteppedpartissimulated.Consideringnodesavingandeffectiveremeshing,thetetrahedronsolidelementsareusedtodiscreteworkpiece.Theworkpiecematerialadoptsrigid-plasticmodel,wheretheflowstressisfunctionofeffectivestrain,effectivestrainrateandtemperature.Thethermomechanicalcouplingisconsideredinthesimulation.Tomodelthespinningworkpieceundergoingplasticdeformation,anovelsolutionispresentedandappliedinthispaper.Thestressstateintheworkpieceandformingcharacteristicofskewrollingareanalyzed.Theformingload,includingrollertorqueandforcesinthreedirectionsarepredicted.Theaboveanalysesarehelpfultounderstandingofformingmechanismsandimprovingofprocessanddiedesign.
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简介:Energy-storageweldingconnectioncharacteristicsofrapidlysolidifiedAZ91DMgalloyribbonswith40~70μmthicknessareinvestigatedusingamicrotypeenergy-storageweldingmachine.Themicrostructureandperformanceoftheconnectionjointsareanalyzedandstudied.Theresearchresultsindicatethatenergy-storageweldingisabletorealizethespotweldingconnectionofAZ9lDMgalloyribbons.Theweldingnuggetconsistsofdevelopedα-Mgequiaxedgrainswiththesizesof1.2~2.7μmandintergranulardistributedβ-Mg17Al12compounds.Thethicknessofbondzoneisabout4μmandthesolidificationmicrostructureischaracterizedbythefineequiaxedgrainswiththesizesof0.8~1.2μm,andgrainboundaryhasbecomecoarsening.ThecolumnarcrystalinHAZalsobecomesslightlycoarseningandthegrainboundaryhasbroadened,however,thereisnoobviouschangeinitsprimitivemorphologyandcrystallographicdirection.Whenweldingenergyisabout2.0J,theweldingjointswithhighershearstrengthandsmallerelectricalresistivityareobtained.
简介:到改善AZ91D镁合金的bioactivity和腐蚀抵抗,有新奇microstructured形态学的hydroxyapatite(幸运)涂层经由一个灵巧的热水的方法在AZ91D底层上成功地被准备。不同chelating代理人包括polyaspartic酸(PASP)和ethylenediaminetetraacetic酸(EDTA)被介绍在形态学和腐蚀上调查他们的效果涂的镁的抵抗合金。结果表明准备与的涂层PASP是许多一致像顽童的microspheres镇静,当与EDTA准备的涂层由许多象花的粒子组成了时。而且,与EDTA准备的涂层的crystallinity比的高是大部分与PASP准备的涂层。电气化学的测试表明底层的腐蚀抵抗显著地在与每涂层是涂的以后被改进。在模仿的身体液体(SBF)的涂的样品的沉浸测试证明涂层能逐渐地是biodegraded并且导致钙磷酸盐粒子的形成。
简介:thermomechanically影响的地区(TMAZ)的微结构进化特征合金在磨擦期间促使处理(FSP)thixoformed(TF),AZ91D合金被调查。同时,合成的层增强了由的表面原文如此,粒子(SiCps)被FSP在合金上准备,相应tribological性质被检验。试验性的结果显示那动态再结晶和机械分离(包括切开和主要谷物的骨折)是为TMAZ的谷物精炼的主要机制。一致地分布式的SiCps增强的合成表面在合金上被准备。与没有合成表面,扔合金和TF合金的相应永久模子相比,有合成表面的TF合金有最高穿抵抗和最低磨擦系数。
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简介:2009年4月17日,联想向业界隆重推出了两款ThinkStation2.0(第二代)工作站产品D20和S20系列,S20是单路工作站,前两期杂志我们连续刊登了评测报告。本期我们对联想高端双路图形工作站D20进行了评测,也将分2期刊登评测报告。