黏弹性热流固耦合作用诱导聚合物变形的机理
|
摘要
模内微装配成型有望成为高效低成本产业化聚合物微型机械制造技术,而如何准确预测和精密控制其二次成型过程的黏弹性热流固耦合变形仍是其工业化的技术瓶颈。基于考虑微装配界面周围高温黏弹性熔体流动环境边界约束作用,建立了描述模内微装配成型黏弹性热流固耦合作用诱导聚合物变形的理论模型。研究表明,黏弹性与纯黏性熔体热流固耦合的本质区别在于熔体的弹性特性能有效抑制微装配界面的热流固耦合作用,使得预成型微型轴的变形和装配界面的热流固耦合载荷均随二次成型熔体松弛时间的延长而减小,且其变形受控于微装配界面所承受的黏弹性热流固耦合压力、黏弹性支撑正应力和黏性拖曳剪切应力,选用高弹性二次成型熔体有利于抑制黏弹性热流固耦合变形,可提高微装配加工精度。
In-mold assembly molding technology is expected to become cost-effective industrial polymer micro mechanical manufacturing technologies,but how to predict accurately and precisely control the viscoelastic thermal-fluidstructure coupling deformation is still the technical bottleneck of industrialization. The theoretical model describing viscoelastic thermal-fluid-structure coupling effect induced polymer deformation was established in in-mold micro assembly molding process based on the boundary restraining influence of the surrounding secondary molding high temperature viscoelastic melt on the micro assembly interface of permolded micro shaft. Research results show that the essential difference between thermal-fluid-structure coupling effect between viscoelastic melt and pure viscous melt is that the elastic properties of secondary molding melt can effectively restrain the thermal-fluid-structure coupling effect on micro assembly interface,which make permolded micro shaft deformation and the micro assembly interfacial thermal-fluid-structure coupling load will reduce with increasing of secondary molding melt relaxation time,and viscoelastic thermal-fluid-structure coupling deformation is controlled by the coupling pressure,viscoelastic support normal stress,viscous friction drag shear stress on the micro assembly interface. It is beneficial to restrain the viscoelastic thermal-fluid-structure coupling deformation,and to improve the molding accuracy of micro assembly by choosing large relaxation time polymeric material for secondary molding micro component.
In-mold assembly molding technology is expected to become cost-effective industrial polymer micro mechanical manufacturing technologies,but how to predict accurately and precisely control the viscoelastic thermal-fluidstructure coupling deformation is still the technical bottleneck of industrialization. The theoretical model describing viscoelastic thermal-fluid-structure coupling effect induced polymer deformation was established in in-mold micro assembly molding process based on the boundary restraining influence of the surrounding secondary molding high temperature viscoelastic melt on the micro assembly interface of permolded micro shaft. Research results show that the essential difference between thermal-fluid-structure coupling effect between viscoelastic melt and pure viscous melt is that the elastic properties of secondary molding melt can effectively restrain the thermal-fluid-structure coupling effect on micro assembly interface,which make permolded micro shaft deformation and the micro assembly interfacial thermal-fluid-structure coupling load will reduce with increasing of secondary molding melt relaxation time,and viscoelastic thermal-fluid-structure coupling deformation is controlled by the coupling pressure,viscoelastic support normal stress,viscous friction drag shear stress on the micro assembly interface. It is beneficial to restrain the viscoelastic thermal-fluid-structure coupling deformation,and to improve the molding accuracy of micro assembly by choosing large relaxation time polymeric material for secondary molding micro component.
引文
[1]Vasuev A.A capillary force microgripper for microassembly using electrowetting-on-dielectric(EWOD)[D].Akron:University of Akron,2009.
[2]Ananthanarayanan A,Gupta S K,Bruck H A.Characterization of a reverse molding sequence at the mesoscale for in-mold assembly of revolute joints[J].Polym.Eng.Sci.,2010,50:1843-1852.
[3]Bejgerowski W.In-mold assembly of multi-functional structures[D].College Park:University of Maryland,2010.
[4]Islam A,Hansen H,Marhfer M,et al.Two-component micro injection moulding for hearing aid applications[J].Int.J.Adv.Manuf.Technol.,2012,62:605-615.
[5]Meister S,Drummer D.Micro assembly injection moulding with variothermal mould tempering[J].Microsyst.Technol.,2017,23:1017-1025.
[6]周国发,阳培民,罗智,等.基于黏弹性热流固耦合作用的模内微装配成型过程数值模拟[J].化工学报,2017,68(3):1129-1137.Zhou G F,Yang P M,Luo Z,et al.Numerical simulation on in mold micro assembly molding process based on viscoelastic thermal fluid structure coupling[J].CIESC Journal,2017,68(3):1129-1137.
[7]周国发,王梅媚,张宇.聚合物多相分层流动黏弹性包围机制的数值模拟研究[J].复合材料学报,2014,31(6):1618-1625.Zhou G F,Wang M M,Zang Y.The numerical simulation on the mechanism of viscoelastic encapsulation in polymer multiphase stratified flows[J].Acta Materiae Compositae Sinica,2014,31(6):1618-1625.
[8]Rajagopalan D,Arrmstrong R C,Brown R A.Finite element methods for calculation of steady viscoelastic flow using constitutive equations with a Newtonian viscosity[J].J.Non-Newtonian Fluid Mech.,1990,36:159-192.
[9]Matthew E D.Demolding of hot embossed polymer microstructures[D].Cambridge:Massachusetts Institute of Technology,2010.
[10]Ananthanarayanan A,Gupta S K,Bruck H A.Modeling and characterization to minimize effects of melt flow fronts on premolded component deformation during in-mold assembly of mesoscale revolute joints[J].J.Manuf.Sci.Eng.,2010,132:575-590.
[11]Ananthanarayanan A,Gupta S K,Bruck H A.Characterization and control of plastic deformation in mesoscale premolded components to realize in-mold assembled mesoscale revolute joints[J].Polym.Eng.Sci.,2009,49:293-304.
[12]周国发,胡舵,刘岑.剪切变稀效应对微型机械模内组装成型流固耦合变形的影响[J].高分子材料科学与工程,2012,28(12):183-186.Zhou G F,Hu D,Liu C.Influence of shear-thinning on polymer micromachine fluid-solid coupling deformation in in-mold assembly molding process[J].Polymer Materials Science&Engineering,2012,28(12):183-186.
[13]周国发,王文光,刘岑.过程参数对微型机械模内组装成型流固耦合变形影响[J].塑性工程学报,2012,19(1):107-112.Zhou G F,Wang W G,Liu C.Influence of process parameters on micromachine fluid-solid coupling deformation in in-mold assembly molding process[J].Journal of Plasticity Engineering,2012,19(1):107-112.
[2]Ananthanarayanan A,Gupta S K,Bruck H A.Characterization of a reverse molding sequence at the mesoscale for in-mold assembly of revolute joints[J].Polym.Eng.Sci.,2010,50:1843-1852.
[3]Bejgerowski W.In-mold assembly of multi-functional structures[D].College Park:University of Maryland,2010.
[4]Islam A,Hansen H,Marhfer M,et al.Two-component micro injection moulding for hearing aid applications[J].Int.J.Adv.Manuf.Technol.,2012,62:605-615.
[5]Meister S,Drummer D.Micro assembly injection moulding with variothermal mould tempering[J].Microsyst.Technol.,2017,23:1017-1025.
[6]周国发,阳培民,罗智,等.基于黏弹性热流固耦合作用的模内微装配成型过程数值模拟[J].化工学报,2017,68(3):1129-1137.Zhou G F,Yang P M,Luo Z,et al.Numerical simulation on in mold micro assembly molding process based on viscoelastic thermal fluid structure coupling[J].CIESC Journal,2017,68(3):1129-1137.
[7]周国发,王梅媚,张宇.聚合物多相分层流动黏弹性包围机制的数值模拟研究[J].复合材料学报,2014,31(6):1618-1625.Zhou G F,Wang M M,Zang Y.The numerical simulation on the mechanism of viscoelastic encapsulation in polymer multiphase stratified flows[J].Acta Materiae Compositae Sinica,2014,31(6):1618-1625.
[8]Rajagopalan D,Arrmstrong R C,Brown R A.Finite element methods for calculation of steady viscoelastic flow using constitutive equations with a Newtonian viscosity[J].J.Non-Newtonian Fluid Mech.,1990,36:159-192.
[9]Matthew E D.Demolding of hot embossed polymer microstructures[D].Cambridge:Massachusetts Institute of Technology,2010.
[10]Ananthanarayanan A,Gupta S K,Bruck H A.Modeling and characterization to minimize effects of melt flow fronts on premolded component deformation during in-mold assembly of mesoscale revolute joints[J].J.Manuf.Sci.Eng.,2010,132:575-590.
[11]Ananthanarayanan A,Gupta S K,Bruck H A.Characterization and control of plastic deformation in mesoscale premolded components to realize in-mold assembled mesoscale revolute joints[J].Polym.Eng.Sci.,2009,49:293-304.
[12]周国发,胡舵,刘岑.剪切变稀效应对微型机械模内组装成型流固耦合变形的影响[J].高分子材料科学与工程,2012,28(12):183-186.Zhou G F,Hu D,Liu C.Influence of shear-thinning on polymer micromachine fluid-solid coupling deformation in in-mold assembly molding process[J].Polymer Materials Science&Engineering,2012,28(12):183-186.
[13]周国发,王文光,刘岑.过程参数对微型机械模内组装成型流固耦合变形影响[J].塑性工程学报,2012,19(1):107-112.Zhou G F,Wang W G,Liu C.Influence of process parameters on micromachine fluid-solid coupling deformation in in-mold assembly molding process[J].Journal of Plasticity Engineering,2012,19(1):107-112.
© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号 地址：北京市海淀区学院路29号 邮编：100083 电话：办公室：(+86 10)66554848；文献借阅、咨询服务、科技查新：66554700 |