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.
出处
《塑性工程学报》
EI
CAS
CSCD
北大核心
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)
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
extrusion
profile
polymer melt flow
viscoelastic flow
extrusion die
numerical simulation
