高分子溶融体の実用的なダイ内シミュレーションに関する研究第1報計算機容量,計算時間が低減できる解析手法の検討
A Study on a Practical Simulation Method for Flow Analysis of Polymer Melt in DiesPart I An Examination of an Analysis Method that Reduced Memory Capacity and CPU Time
榊 一任・桑野善文・梶原稔尚・船津和守
Sakaki, Kazutaka / Kuwano, Yoshifumi / Kajiwara, Toshihisa / Funatasu, Kazumori
We examined two kinds of numerical analysis method for polymer melt flow in dies, that could reduce the memory capacity and the CPU time. The first method was an approximate analysis method in which the velocity field was calculated by a pure-viscous non-Newtonian model and the stress field was obtained by substituting the velocity field in a viscoelastic model. The second method was used a viscoelastic model in which the extra-stress is represented by an explicit function of the velocity and the deformation rate. It was found that both methods could reduce both the memory capacity and the CPU time. In the approximate analysis method, the stress calculation did not converge at high shear rates when we used the finite element method in previous work. But, in the present work, the stress solution could be obtained up to high shear rates using streamwise integration of the constitutive equation. The calculated results by the approximate analysis method were compared with the results obtained by a mixed method using the Giesekus model for tapered contraction flow. Both results agreed within the region where the shear and the elongational viscosities of the pure-viscous non-Newtonian and the viscoelastic models coincided with each other. But this method could not apply to a polymer with strain-thickening elongational viscosity because the pure-viscous non-Newtonian model could not represent its characteristics. In the second method, we used the Criminale-Ericksen-Filbey (CEF) model and a simplified-CEF model as the viscoelastic models in which the extra-stress was an explicit function of the velocity and deformation rate. The solutions for both models could not be obtained up to a high shear rate, but in the low shear rate region, the results using both models agreed with the results using the Giesekus model.
Key words: Polymer melts / Numerical simulation / Approximate analysis method / Streamwise integration method / Criminale-Ericksen-Filbey model