基于Navier滑移模型的聚合物挤出成型有限元模拟

Finite Element Simulation Based on Navier Slip Molding in Polymer Extrusion Molding

基于聚合物挤出成型过程中壁面滑移机理,采用Navier滑移模型,利用有限元方法对聚合物挤出过程进行了数值模拟。基于微观壁面滑移机理对壁面滑移进行了理论分析,获得了不同滑移系数对熔体的速度、剪切速率和压力的影响规律。研究结果表明:随着壁面滑移系数减小,熔体在模具出口截面的速度梯度减小,熔体出口速度逐渐趋于一致,逐渐呈柱塞流;熔体剪切速率和剪切应力减小,靠近壁面的大分子间出现解缠,或与壁面吸附力减弱,熔体滑移程度增强,熔体内速度梯度减小;熔体流动所受的阻流作用减小,压力降减小,有利于熔体流动。

With wall slip considered,polymer extrusion molding process was studied by finite element method with the Navier silp model.Based on microscopic silp wall mechanism,the effects of wall silp on the melt velocity,pressure and shear rate with different silp coefficient were analyzed.The results show that the melt velocity gradient across the exit section dereases with the wall silp coefficient dereases and the velocity gradually becomes uniform.Meanwhile,with the shear rate and shear stress decrease,macromolecules near the wall unwrap or the surface adsorption force abates,wall silp enhances and the velocity gradient in the melt decreases.The melt flow resistance reduces and the pressure drop decreases which is good for melt flow.