Journal article
3D modeling of dual wind-up extensional rheometers
Manufacturing Engineering, Department of Mechanical Engineering, Technical University of Denmark1
Department of Mechanical Engineering, Technical University of Denmark2
The Danish Polymer Centre, Department of Chemical and Biochemical Engineering, Technical University of Denmark3
Department of Chemical and Biochemical Engineering, Technical University of Denmark4
Fully three-dimensional numerical simulations of a dual wind-up drum rheometer of the Sentmanat Extensional Rheometer (SER; Sentmanat, 2004 [1]) or the Extensional Viscosity Fixture (EVF; Garritano and Berting, 2006 [2]) type have been performed. In the SER and EVF a strip of rectangular shape is attached onto two drums, followed by a rotation of both drums in opposite direction.
The numerical modeling is based on integral constitutive equations of the K-BKZ type. Generally, to ensure a proper uni-axial extensional deformation in dual wind-up drum rheometers the simulations show that a very small initial width and initial thickness of the strip is required. In the SER it requires an initial sample width of less than 2.5 mm and a thickness of less than 0.25 mm.
This is typically observed for elastomer model. The overall picture is though more diverse, as the possibility to perform ideal uni-axial extension is very dependent of the constitutive equation. Especially the weighting between the convected relative strain tensors in the K-BKZ model seems to control the deviation from ideal behavior.
Consequently, for melts or entangled liquids a proper uni-axial flow will be kept for a much wider parameter range. In fact only the appearance of a ductile necking or a large initial thickness of the sample will create a significant deviation from ideal extension. These simulations were based on MSF constitutive model.
Language: | English |
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Year: | 2010 |
Pages: | 14-23 |
ISSN: | 18732631 and 03770257 |
Types: | Journal article |
DOI: | 10.1016/j.jnnfm.2009.08.006 |
ORCIDs: | Rasmussen, Henrik K. and Hassager, Ole |
BKZ EVF Elongation Extension Finite element Lagrangian Rheometer SER