马鞍型异型材挤出成型过程三维等温粘弹性的数值模拟

基于PTT粘弹性本构模型,通过马鞍型异型材挤出成型过程的全三维稳态等温有限元数值模拟,系统研究了聚合物粘弹性流变性能参数和成型工艺参数对异型材口模挤出成型过程的影响规律,并揭示了其影响机理.研究结果表明,聚合物异型材口模挤出离模膨胀是由口模出口处的二次流动引起,离模膨胀比随着口模出口处的二次流动强度增加而增大.聚合物异型材口模挤出离模膨胀随着进口流量和聚合物熔体松弛时间的增加而增加,而随着聚合物熔体材料常数和粘度比的增大而减小.

THREE DIMENSIONAL ISOTHERMAL VISCOELASTIC NUMEIUCAL SIMULATION ON THE EXTRUSION MOLDING OF POLYMERIC SADDLE PROFILE

Based on viscoelastic PTT constitutive equation, by means of the full three dimensional isothermal viscoelastic numerical simulation on the extrusion molding process of polymeric saddle profile, the influencing rule of polymeric melt viscoelastic rheological parameters and process parameters on polymeric profile molding process were systematically studied and the influencing mechanism was disclosed. The research results showed that the die swell of polymeric profile was resulted from the secondary flow in the exit of the die, the die swell ratio of polymeric profile increased with the increasing of the secondary flow strength. The die swell of polymeric profile increased with the increasing of inlet volumetric flow rate and relaxation time, but decreased with the increasing of material parameter and viscosity ratio.