Y型异型材气辅共挤出胀大的三维等温数值模拟
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摘要
采用Phan-Thien-Tanner本构方程,建立Y型包覆挤出模型,通过有限元数值模拟聚苯乙烯、聚丙烯的三维等温高黏弹流动过程,对比不同进料组合条件下流体在传统和气辅流动中的速率场、剪切速率分布。结果表明:传统共挤出受不同进料方式的影响,挤出物胀大主要由其各向速率场量分布不匀造成,而气辅共挤出的挤出物胀大不受其影响,且胀大均基本得到消除;气辅共挤出时,其x轴、y轴方向的速率均几乎为零,没有二次流动,且z轴向的速率稳定,说明气辅共挤出能消除挤出物膨胀现象。
The three-dimensional isothermal viscoelastic processes of polystyrene and polypropylene were simulated by the finite element method based on Y-shaped co-extrusion model which was established by the Phan-Thien-Tanner constitutive equation.The distributions of velocity field and shear rate of polymer with different feedstock were compared in conventional and gas-assisted co-extrusion.The results show that the die swell in conventional co-extrusion affected by feeding method,is mainly caused by the uneven distribution of velocity field in every direction,while the die swell in gas-assisted co-extrusion is not affected and almost eliminated.Both of the velocity of x and y are zero in the process of gas-assisted co-extrusion,therefore there is no secondary flow,furthermore,the flow rate is uniform at the direction of z,which indicates that the die swell can be eliminated in gas-assisted profile co-extrusion.
The three-dimensional isothermal viscoelastic processes of polystyrene and polypropylene were simulated by the finite element method based on Y-shaped co-extrusion model which was established by the Phan-Thien-Tanner constitutive equation.The distributions of velocity field and shear rate of polymer with different feedstock were compared in conventional and gas-assisted co-extrusion.The results show that the die swell in conventional co-extrusion affected by feeding method,is mainly caused by the uneven distribution of velocity field in every direction,while the die swell in gas-assisted co-extrusion is not affected and almost eliminated.Both of the velocity of x and y are zero in the process of gas-assisted co-extrusion,therefore there is no secondary flow,furthermore,the flow rate is uniform at the direction of z,which indicates that the die swell can be eliminated in gas-assisted profile co-extrusion.
引文
[1]高峰,李海梅,申长雨.塑料成型加工实用技术讲座(第七讲):塑料异型材的挤出成型[J].工程塑料应用,2003,31(9):58-62.
[2]张敏,黄传真,贾玉玺.气辅共挤出流道中聚合物流动过程的数值分析[J].高分子材料科学与工程,2012,28(1):176-179.
[3]Miller J C,Rallison J M.Instability of coextruded elastic liquids at high Weissenberg number[J].J Non Newton Fluid Mech,2007,143(2/3):88-106.
[4]Zhang Min,Jia Yuxi,Sun Sheng,et al.Three-dimensional nonisothermal simulation of multi-layer extrusion processes of polymer melts[J].Polym-Plast Technol,2006,45(11):1257-1262.
[5]周文彦,周国发.聚合物多层气辅共挤精密成型机制的数值分析[J].复合材料学报,2009,26(3):90-98.
[6]黄益宾,柳和生,黄兴元,等.聚合物气辅共挤成型中挤出胀大的数值模拟[J].高分子材料科学与工程,2010,26(5):171-174.
[7]Phan-Thien N,Tanner R I.A new constitutive equation derived from network theory[J].J Non Newton Fluid Mech,1977,2(4):353-365.
[8]黄益宾,柳和生,黄兴元,等.复合共挤成型中挤出胀大的三维粘弹数值模拟[J].高分子材料科学与工程,2010,26(3):160-163.
[9]Fluent Inc.Polyflow 3.10 user's guide[M].Belgium:Fluent Inc,2003:187-189.
[2]张敏,黄传真,贾玉玺.气辅共挤出流道中聚合物流动过程的数值分析[J].高分子材料科学与工程,2012,28(1):176-179.
[3]Miller J C,Rallison J M.Instability of coextruded elastic liquids at high Weissenberg number[J].J Non Newton Fluid Mech,2007,143(2/3):88-106.
[4]Zhang Min,Jia Yuxi,Sun Sheng,et al.Three-dimensional nonisothermal simulation of multi-layer extrusion processes of polymer melts[J].Polym-Plast Technol,2006,45(11):1257-1262.
[5]周文彦,周国发.聚合物多层气辅共挤精密成型机制的数值分析[J].复合材料学报,2009,26(3):90-98.
[6]黄益宾,柳和生,黄兴元,等.聚合物气辅共挤成型中挤出胀大的数值模拟[J].高分子材料科学与工程,2010,26(5):171-174.
[7]Phan-Thien N,Tanner R I.A new constitutive equation derived from network theory[J].J Non Newton Fluid Mech,1977,2(4):353-365.
[8]黄益宾,柳和生,黄兴元,等.复合共挤成型中挤出胀大的三维粘弹数值模拟[J].高分子材料科学与工程,2010,26(3):160-163.
[9]Fluent Inc.Polyflow 3.10 user's guide[M].Belgium:Fluent Inc,2003:187-189.