聚合物熔体在L型异型材挤出口模内三维粘弹流动数值模拟  

Numerical simulation of three dimensional viscoelastic polymer melt flow through the extrusion die with an L-shaped cross section

作　　者：柳和生[1] 涂志刚[1] 熊洪槐[1] 

机构地区：[1]南昌大学机电工程学院聚合物加工研究室,南昌330029

出　　处：《塑性工程学报》2007年第2期114-117,共4页Journal of Plasticity Engineering

基　　金：国家自然科学基金(59763002);江西省自然科学基金(0550075)

摘　　要：利用罚函数有限元法,采用PTT粘弹模型,对聚合物熔体在L型异型材挤出口模内的三维等温流动进行了数值模拟,得出了不同挤出量下的速度和应力分布。结果表明,流速在成型区内并在其入口附近达到其在口模内的最大值;剪切应力在成型区内并在其入口附近明显持续上升,达到其在口模内的最大值后迅速回落;第一法向应力差在过渡区内并在其出口附近达到其在口模内的最大值,此后在过渡区和成型区的结合面两端近距离内急剧下降,因此成型区和过渡区接合处是熔体流动不稳定的发源地;口模内最大剪切应力和最大第一法向应力差均随挤出量的增加而近似呈线性上升,而不会急剧增加。In this paper, by means of penalty finite element method and PTT viscoelastic constitutive model, numerical simulation is implemented for the three dimensional viscoelastic polymer melt flow through the die for extrusion of the product with an L- shaped cross section. The distributions of velocity and stress under various flow rates are worked out. Within the forming zone, near its entrance, the velocity reaches its maximum; the shear stress grows clearly, reaches its maximum and then drops rapidly. Within the transition zone, near its exit, the first normal stress difference reaches its maximum, and then drops drastically within a short distance across the joint of the transition zone and the forming zone. Therefore, unstable flow may occurs within the vicinity of the joint of the transition zone and the forming zone. The maximum of shear stress and that of the first normal stress difference within the die grows almost linearly but not drastically with the increase of the flow rate.

关 键 词：挤出 异型材 聚合物流动 粘弹流动 挤出口模 数值模拟 

分 类 号：TQ320.663[化学工程—合成树脂塑料工业]