表面张力论文：表面张力壁面滑移微观粘度数值模拟熔体前沿

1、表面张力论文：表面张力壁面滑移微观粘度数值模拟熔体前沿【中文摘要】降低原材料耗费，扩展塑件的功能和应用领域是聚合物成型永恒的话题。这使得微注塑成型成为微成型领域的热点之一。本文通过假定适当的边界条件和初始条件，对聚合物熔体的充填流动行为进行了研究，引出了三个在注塑成型中与流道尺寸无关的参数。通过对聚合物熔体在微尺寸下非等温流动的数值模拟，分析了表面张力,黏度的尺寸效应和壁面滑移对其流动的影响，论文主要内容如下：1.分析了聚合物熔体充填流动过程中界（表）面能的变化，将作用在熔体前沿的界（表）面张力的影响，转化为熔体前沿的附加压力降。2.对常规注塑成型充填过程的控制方程进行了分析并得到了三个与流道

2、尺寸无关的流变学参数。在控制方程中添加了表面张力，黏度的尺寸效应和壁面滑移对熔体流动的影响。3.通过对聚合流动行为的数值模拟,探讨了各种尺寸效应对聚合物熔体充填过程中流变参数的影响。4.采用直径为1卩m,10m,和100卩m的微流道作为几何模型，分析了五种数学模型描述的聚合物熔体在不同的表观剪切速率下流动前沿的无量纲速率沿径向的分布规律，探讨了在不同的剪切速率和流道尺寸下各种尺寸微观效应对聚合物熔体的充填行为的影响。模拟结果表明在极小的尺寸和低的表观剪切速率下，表面张力在三种微观效应中占主导地位下，随着流道尺寸的增加，表面张力和黏度的尺寸效应衰减,转而壁面滑移成为对流动影响最大的尺寸效应。【英

3、文摘要】Itisbecameatrendthathowtomakeplasticpartshavemoremicro-structures,functionandreducetheirsize.Weinvestigatethebehaviorofpolymericflowfillingthemicro-channelsandgetthethreenon-dimensionalparameters.Numericalsimulationofnon-isothermalflowwasusedtoanalysistheeffectsofsurfacetension,size-dependentvis

4、cosityandwallslipaboutthepolymericflowfillingthemicro-channel.Themajorconclusionsarefollowing:1.Wehaveinvestigatedthechangeofinterfaceenergyofthreephasesystemsamountpolymericflow,thewallofmicro-channelsandatmosphere,whenpolymericflowfillingthemicro-channels.Theeffectofinterface(surface)tensionwastra

5、nslatedintotheexternpressurelossatthefrontofmelt.2.Inoldertodescribethebehaviorsofpolymericflowfillingthechannels,thecontrolequationthatwasusedtodescribedconventionalinjectionmoldingoffillingprocesswasrevisedbyconsideringtheeffectsofsurfacetension,size-dependentviscosityandwallslip.Wealsogetthreenor

6、malizedrheologicalparameters.3.Thenumericalsimulationofpolymericflowfillingthemicro-channelswasusedtoanalysistheconsequencesofmicro-scalephenomena,particularly,surfacetension,size-dependentviscosityandwallslip.4.Atdifferentapparentshearingrate,weinvestigatedradialdistributenofnormalizedvelocityatmel

7、tfrontaboutfivedifferentmodels.Wechoosethreedifferentsizemicro-channelsasgeometricalmodel,thediametersofwhichare1卩m,10卩m,100m.Theresultsofnumericalsimulationshowthattheeffectsofsurfacetension,wallslipandsize-dependentviscosityallplayimportantrolesonthefillingprocess.Whenthediameterofmicro-channelis1

8、0卩m,theeffectofsurfacetensionismoreimportantthanotherconsequencesofmicro-scalephenomena,astheapparentshearingrateislowthan1.0x102s-1.Astheshearingratebecomehigher,theeffectsofsurfacetensionandsize-dependentviscositywilldecreaseandtheeffectofwallslipwillincrease.Thesmallerdiameterofchannelwillmaketheeffectofsurfacetensionbecomemoreimportant.【关键词】表面张力壁面滑移微观粘度数值模拟熔体前沿【英文关键词】SurfacetensionWallslipMicro-viscosityNumericalsimulationMeltfront【目录】微尺寸下聚合物熔体充填过程的研究摘