全文下载：2012010068
许星明1, 秦升学2， 韩咚3
（1. 山东科技大学泰安校区 机电系，山东 泰安 271019； 2. 山东科技大学 机电学院，山东 青岛 266510；
3. 山东科技大学泰安校区 继续教育学院，山东 泰安 271019）
摘要： 挤出胀大是塑料圆形管材生产过程中不可避免的一种现象。在实际生产中，目前主要采用传统经验试差方法设计挤出口模，缺乏相关的理论研究及指导。本研究针对管材挤出工艺，建立了几何模型和数学模型，采用稳态不可压缩流体流动的有限元模型，模拟了PTT流体经过圆环口模挤出胀大现象。采用罚有限元将连续性方程引入动量方程，减少了同时计算的变量数，有效提高了计算效率。模拟结果表明，口模出口处聚合物熔体表面第一法向应力差急剧增大。口模尺寸一定时，聚合物的挤出胀大率随体积流量的增大而增大。同时也系统分析了口模尺寸对挤出胀大的影响规律。模拟结果对实际生产中的模具设计具有一定的指导意义。
关键词： 黏弹流体； 挤出胀大； 罚有限元
中图分类号： O 241; TG 376.9文献标志码： A
Numerical Simulation of Extrudate Swell for Plastic Circular Pipes
XU Xing-ming1, QIN Sheng-xue2, HAN Dong3
( 1. College of Mechanical and Electrical Engineering, Shandong University of Science and Technology, Tai’an 271019, China;
2. College of Mechanical and Electrical Engineering, Shandong University of Science and Technology, Qingdao 266510, China;
3.Adult Education College,ShandongUniversityofScienceand Technology, Tai’an 271019,China)
Abstract: Extrudate swell is a common phenomenon in the productive process of plastics pipes. The traditional trail and error method is widely used in the design of extrusion die,but lack related theory research and direction. Based on the process of plastic circular pipe extrusion, geometry model and mathematics model were established in this paper. Finite element model for stable incompressible flow was introduced to simulate annular extrudate swell of PTT fluid. By introducing continuity equation into momentum equation, velocity field was obtained with penalty finite element method while the incompressible constraint was satisfied approximately. And computational efficiency was also increased. According the numerical simulation results, the first normal-stress difference along polymer surface increased rapidly near the outlet of the die. The extrudate swell ratio increased with the increase of volumetric flow rate. The effect of die dimension on extrudate swell was also discussed in detail. The simulation results had some guiding significance for practical production and die design.
Key words: viscoelastic fluid; extrudate swell; penalty finite element
收稿日期：2011-06-14
基金项目： 山东科技大学春蕾计划资助项目（2010AZZ096）.
作者简介： 许星明（1981—），女，博士,讲师.
