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Modeling of coupled thermoplasticity at finite strains

Håkansson, Paul LU (2007)
Abstract
In this thesis, models for simulation of inelastic phenomena, such as plastic anisotropy, texture evolution, void growth and phase transformation are presented. Special emphasized is put on the modeling of heat generation due to plastic work. All models are formulated within a thermodynamic framework that allows large deformations. The thermodynamic framework is used as a base for the formulation of the coupled thermomechanical problem, where the mechanical dissipation will serve as a heat source in the heat equation. Heat generation effects are studied for plastic anisotropic materials. The first investigation is performed using a mixed isotropic and kinematic hardening constitutive mode. The non-associated formulation of the model makes... (More)
In this thesis, models for simulation of inelastic phenomena, such as plastic anisotropy, texture evolution, void growth and phase transformation are presented. Special emphasized is put on the modeling of heat generation due to plastic work. All models are formulated within a thermodynamic framework that allows large deformations. The thermodynamic framework is used as a base for the formulation of the coupled thermomechanical problem, where the mechanical dissipation will serve as a heat source in the heat equation. Heat generation effects are studied for plastic anisotropic materials. The first investigation is performed using a mixed isotropic and kinematic hardening constitutive mode. The non-associated formulation of the model makes it possible to, in addition to the mechanical behavior, predict an accurate heat generation. A thermodynamically consistent single crystal plasticity model is developed. The model is used study the heat generation in textured material during cyclic loading. One failure mechanism in ductile metals involves nucleation and growth of voids, which eventually leads to crack propagation. Temperature evolution and heat generation in connection with void growth are studied with a Gurson model. The Gurson model, which is extended to also consider non-local porosity effects, is used in fully coupled thermomechanical simulations, including localization problems and crack propagation. Many austenitic stainless steels undergo a change of microstructure from austenite to martensite when they are loaded. A model that considers the evolution of phase transformation, as well as plastic flow in form of slip, is developed within a thermodynamic framework for large deformations. The model is used in necking simulations where it is studied how the phase transformation affects the localizations. The effects of phase transformation in sheet metal forming are also studied. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Krenk, Steen, Technical University of Denmark, Kongens Lyngby, Danmark
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Mechanical engineering, hydraulics, vacuum technology, vibration and acoustic engineering, Maskinteknik, Heat generation, Phase transformation, Void growth, Thermoplasticity, hydraulik, vakuumteknik, vibrationer, akustik, Crystal plasticity, Finite element
publisher
Div. of Solid Mechanics, Lund University, P.O. Box 118, SE-221 00 Lund
defense location
Room M:B, M-Building Ole Römers väg 1 Lund
defense date
2007-02-16 10:15
external identifiers
  • Other:ISRN:LUTFD2/TFHF--07/1036
ISBN
978-91-628-7064-5
language
English
LU publication?
yes
id
e32a18de-2ae5-4b4a-9f6b-9a842967299a (old id 547975)
date added to LUP
2007-09-07 13:13:49
date last changed
2016-09-19 08:45:03
@phdthesis{e32a18de-2ae5-4b4a-9f6b-9a842967299a,
  abstract     = {In this thesis, models for simulation of inelastic phenomena, such as plastic anisotropy, texture evolution, void growth and phase transformation are presented. Special emphasized is put on the modeling of heat generation due to plastic work. All models are formulated within a thermodynamic framework that allows large deformations. The thermodynamic framework is used as a base for the formulation of the coupled thermomechanical problem, where the mechanical dissipation will serve as a heat source in the heat equation. Heat generation effects are studied for plastic anisotropic materials. The first investigation is performed using a mixed isotropic and kinematic hardening constitutive mode. The non-associated formulation of the model makes it possible to, in addition to the mechanical behavior, predict an accurate heat generation. A thermodynamically consistent single crystal plasticity model is developed. The model is used study the heat generation in textured material during cyclic loading. One failure mechanism in ductile metals involves nucleation and growth of voids, which eventually leads to crack propagation. Temperature evolution and heat generation in connection with void growth are studied with a Gurson model. The Gurson model, which is extended to also consider non-local porosity effects, is used in fully coupled thermomechanical simulations, including localization problems and crack propagation. Many austenitic stainless steels undergo a change of microstructure from austenite to martensite when they are loaded. A model that considers the evolution of phase transformation, as well as plastic flow in form of slip, is developed within a thermodynamic framework for large deformations. The model is used in necking simulations where it is studied how the phase transformation affects the localizations. The effects of phase transformation in sheet metal forming are also studied.},
  author       = {Håkansson, Paul},
  isbn         = {978-91-628-7064-5},
  keyword      = {Mechanical engineering,hydraulics,vacuum technology,vibration and acoustic engineering,Maskinteknik,Heat generation,Phase transformation,Void growth,Thermoplasticity,hydraulik,vakuumteknik,vibrationer,akustik,Crystal plasticity,Finite element},
  language     = {eng},
  publisher    = {Div. of Solid Mechanics, Lund University, P.O. Box 118, SE-221 00 Lund},
  school       = {Lund University},
  title        = {Modeling of coupled thermoplasticity at finite strains},
  year         = {2007},
}