Molecular chain plasticity model considering poly-entangled points of molecular chain in glassy polymer and large deformation FE analysis on deformation-induced anisotropy

Hironori Nada, Yuichi Tadano, Kazuyuki Shizawa

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1 Citation (Scopus)

Abstract

In the previous paper, a concept of "molecular chain slip system" was newly proposed for glassy polymer by analogy with the crystal plasticity theory for metals. An inelastic response law based on a probabilistic theory considering change of local free volume was adopted as a hardening law. An FE simulation was carried out for PMMA under plane strain tension. Macroscopic neck propagation with high strain rate shear band and directions of molecular chains in the oriented region were computationally visualized. Moreover, a nonlinear viscoelastic behavior was accurately predicted. However, amorphous state in which molecular chains were entangled at random was not expressed appropriately because same initial directions of molecular chains were given to each material point. In addition, elastic isotropy was assumed and change of elastic modulus due to orientation of molecular chains was not considered. In this paper, the extended Taylor model, in which many slip systems are given to a material point and their initial directions are random, is applied to the present theory in order to represent more realistic amorphous state of glassy polymer. Furthermore, anisotropy parameter is defined from dispersion of slip system directions and it is attempted to express an elastic anisotropy induced by molecular chain orientation with plastic deformation, introducing anisotropy parameter into the elastic constitutive equation.

Original languageEnglish
Pages (from-to)961-970
Number of pages10
JournalNihon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A
Volume74
Issue number7
Publication statusPublished - 2008 Jul

Fingerprint

Plasticity
Polymers
Anisotropy
Shear bands
Free volume
Constitutive equations
Hardening
Strain rate
Plastic deformation
Polymethyl Methacrylate
Elastic moduli
Crystals
Metals
Direction compound

Keywords

  • Anisotropy
  • Constitutive equation
  • Crystal plasticity
  • Extended taylor model
  • Finite deformation theory
  • Finite element method
  • Inelasticity
  • Molecular chain
  • Polymer

ASJC Scopus subject areas

  • Mechanical Engineering
  • Mechanics of Materials
  • Materials Science(all)

Cite this

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title = "Molecular chain plasticity model considering poly-entangled points of molecular chain in glassy polymer and large deformation FE analysis on deformation-induced anisotropy",
abstract = "In the previous paper, a concept of {"}molecular chain slip system{"} was newly proposed for glassy polymer by analogy with the crystal plasticity theory for metals. An inelastic response law based on a probabilistic theory considering change of local free volume was adopted as a hardening law. An FE simulation was carried out for PMMA under plane strain tension. Macroscopic neck propagation with high strain rate shear band and directions of molecular chains in the oriented region were computationally visualized. Moreover, a nonlinear viscoelastic behavior was accurately predicted. However, amorphous state in which molecular chains were entangled at random was not expressed appropriately because same initial directions of molecular chains were given to each material point. In addition, elastic isotropy was assumed and change of elastic modulus due to orientation of molecular chains was not considered. In this paper, the extended Taylor model, in which many slip systems are given to a material point and their initial directions are random, is applied to the present theory in order to represent more realistic amorphous state of glassy polymer. Furthermore, anisotropy parameter is defined from dispersion of slip system directions and it is attempted to express an elastic anisotropy induced by molecular chain orientation with plastic deformation, introducing anisotropy parameter into the elastic constitutive equation.",
keywords = "Anisotropy, Constitutive equation, Crystal plasticity, Extended taylor model, Finite deformation theory, Finite element method, Inelasticity, Molecular chain, Polymer",
author = "Hironori Nada and Yuichi Tadano and Kazuyuki Shizawa",
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AU - Tadano, Yuichi

AU - Shizawa, Kazuyuki

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N2 - In the previous paper, a concept of "molecular chain slip system" was newly proposed for glassy polymer by analogy with the crystal plasticity theory for metals. An inelastic response law based on a probabilistic theory considering change of local free volume was adopted as a hardening law. An FE simulation was carried out for PMMA under plane strain tension. Macroscopic neck propagation with high strain rate shear band and directions of molecular chains in the oriented region were computationally visualized. Moreover, a nonlinear viscoelastic behavior was accurately predicted. However, amorphous state in which molecular chains were entangled at random was not expressed appropriately because same initial directions of molecular chains were given to each material point. In addition, elastic isotropy was assumed and change of elastic modulus due to orientation of molecular chains was not considered. In this paper, the extended Taylor model, in which many slip systems are given to a material point and their initial directions are random, is applied to the present theory in order to represent more realistic amorphous state of glassy polymer. Furthermore, anisotropy parameter is defined from dispersion of slip system directions and it is attempted to express an elastic anisotropy induced by molecular chain orientation with plastic deformation, introducing anisotropy parameter into the elastic constitutive equation.

AB - In the previous paper, a concept of "molecular chain slip system" was newly proposed for glassy polymer by analogy with the crystal plasticity theory for metals. An inelastic response law based on a probabilistic theory considering change of local free volume was adopted as a hardening law. An FE simulation was carried out for PMMA under plane strain tension. Macroscopic neck propagation with high strain rate shear band and directions of molecular chains in the oriented region were computationally visualized. Moreover, a nonlinear viscoelastic behavior was accurately predicted. However, amorphous state in which molecular chains were entangled at random was not expressed appropriately because same initial directions of molecular chains were given to each material point. In addition, elastic isotropy was assumed and change of elastic modulus due to orientation of molecular chains was not considered. In this paper, the extended Taylor model, in which many slip systems are given to a material point and their initial directions are random, is applied to the present theory in order to represent more realistic amorphous state of glassy polymer. Furthermore, anisotropy parameter is defined from dispersion of slip system directions and it is attempted to express an elastic anisotropy induced by molecular chain orientation with plastic deformation, introducing anisotropy parameter into the elastic constitutive equation.

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