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Unified model of necking and shear banding in amorphous and semicrystalline polymers
Author(s) -
Sweeney J.,
CatonRose P.,
Spares R.,
Coates P. D.
Publication year - 2007
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.26546
Subject(s) - necking , materials science , amorphous solid , composite material , shear (geology) , polymer , von mises yield criterion , polyethylene , polycarbonate , mechanics , thermodynamics , physics , chemistry , finite element method , crystallography
In tensile stretching, many polymers undergo strain localization. The geometrical form of the localization can take the form of either a shear band or an approximately symmetric neck. We present a constitutive model of the early stages of deformation that predicts which form the localization will take. The model consists of an Eyring process acting with a Gaussian network that is implemented numerically. A Levy–Mises flow rule associated with the Eyring process has a tendency to produce shear bands. A relatively stiff Gaussian network is used in a model of polycarbonate that ensures that most of the strain is taken up by the Eyring process, resulting in shear banding. In contrast, a relatively soft Gaussian network is used in a model of polyethylene, which takes up the greater part of the strain, resulting in a neck. The predictions are compared with experiments. For polyethylene, a two‐Eyring‐process model is introduced for better accuracy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007