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Finite element simulation of long and short circular die extrusion experiments using integral models
Author(s) -
Luo X.L.,
Tanner R. I.
Publication year - 1988
Publication title -
international journal for numerical methods in engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.421
H-Index - 168
eISSN - 1097-0207
pISSN - 0029-5981
DOI - 10.1002/nme.1620250104
Subject(s) - extrusion , low density polyethylene , materials science , viscoelasticity , finite element method , die (integrated circuit) , mechanics , swelling , extrusion moulding , stress relaxation , constitutive equation , thermodynamics , composite material , polyethylene , creep , physics , nanotechnology
A finite streamline element method for use with integral type constitutive equations in viscoelastic flow simulation, including thermal effects, is presented and some new results using this method in modelling the IUPAC extrusion experiments for low‐density polyethylene (LDPE), involving both long and short circular dies, are reported and discussed. It will be shown that the special streamline‐based elements provide a convenient way of particle tracking and strain tensor calculation. The extrusion calculation when using a relatively realistic KBKZ type integral model with multiple relaxation times is stable, and practically important Weissenberg numbers and swelling ratios have been reached without difficulty. The agreement with experimental swelling ratios is on the whole satisfactory. In order to make the model a good fit to the Trouton viscosity experimental data of the LDPE sample, a spectrum of elongational parameters has been introduced. The second normal stress term has also been added to the integral model to examine its effect on extrusion swelling. The non‐isothermal effects and the possibility of a wall slip near the die exit at high apparent shear rates are also discussed.