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Thermo-Viscoplasticity for Case Hardening Steels at Finite Deformations and Wide Temperature Ranges

Oppermann, Philip LU orcid ; Denzer, Ralf LU and Menzel, Andreas LU (2019) COMPLAS 2019
Abstract
The aim of this work is the development of a thermodynamically consistent fully coupled thermo-viscoplastic material model for metals undergoing finite deformation and large temperature changes.

The deformation gradient is supposed to be decomposable into a thermal, an elastic, and a plastic part, where purely volumetric thermal expansion and isochoric plastic distortion is assumed. The model is based on a split of the free energy into a thermo-elastic and a plastic part. Where the first part is dependent on the elastic deformation gradient and the temperature, and the latter, covering non-linear cold-work hardening, shall only depend on the internal variables. Within this ansatz for the free energy and the kinematics, nonlinear... (More)
The aim of this work is the development of a thermodynamically consistent fully coupled thermo-viscoplastic material model for metals undergoing finite deformation and large temperature changes.

The deformation gradient is supposed to be decomposable into a thermal, an elastic, and a plastic part, where purely volumetric thermal expansion and isochoric plastic distortion is assumed. The model is based on a split of the free energy into a thermo-elastic and a plastic part. Where the first part is dependent on the elastic deformation gradient and the temperature, and the latter, covering non-linear cold-work hardening, shall only depend on the internal variables. Within this ansatz for the free energy and the kinematics, nonlinear temperature dependent effects are accounted for the elastic moduli, the thermal expansion, the heat capacity and the heat conductivity.

Based on an associative flow rule, strain rate-dependency of the current yield stress is realised using a temperature dependent nonlinear Perzyna-type viscoplastic model in combination with a von Mises yield function enhanced by non-linear thermal softening. The model and its parameters are fitted against experimental data for case hardening steel 16MnCr5 (1.7131).

We discuss the consistent linearisation of the proposed model and its implementation in a monolithic fully coupled finite element framework. Special care has been taken on the implementation of the incompressibility constraint on the plastic deformation gradient. Finally, we present results for selected boundary value problems demonstrating the performance of the model. (Less)
Please use this url to cite or link to this publication:
author
; and
organization
publishing date
type
Contribution to conference
publication status
published
subject
keywords
Thermoplasticity, Finite element (FE) numerical modeling, Thermodynamics, Thermomechanics, Thermomechanical processes
pages
1 pages
conference name
COMPLAS 2019
conference location
Barcelona, Spain
conference dates
2019-09-03 - 2019-09-05
language
English
LU publication?
yes
id
d03d57eb-131c-42ef-8a0f-f0c02922922e
alternative location
https://congress.cimne.com/complas2019/admin/files/fileabstract/a123.pdf
date added to LUP
2019-10-24 13:44:04
date last changed
2022-02-14 12:22:09
@misc{d03d57eb-131c-42ef-8a0f-f0c02922922e,
  abstract     = {{The aim of this work is the development of a thermodynamically consistent fully coupled thermo-viscoplastic material model for metals undergoing finite deformation and large temperature changes.<br/><br/>The deformation gradient is supposed to be decomposable into a thermal, an elastic, and a plastic part, where purely volumetric thermal expansion and isochoric plastic distortion is assumed. The model is based on a split of the free energy into a thermo-elastic and a plastic part. Where the first part is dependent on the elastic deformation gradient and the temperature, and the latter, covering non-linear cold-work hardening, shall only depend on the internal variables. Within this ansatz for the free energy and the kinematics, nonlinear temperature dependent effects are accounted for the elastic moduli, the thermal expansion, the heat capacity and the heat conductivity.<br/><br/>Based on an associative flow rule, strain rate-dependency of the current yield stress is realised using a temperature dependent nonlinear Perzyna-type viscoplastic model in combination with a von Mises yield function enhanced by non-linear thermal softening. The model and its parameters are fitted against experimental data for case hardening steel 16MnCr5 (1.7131).<br/><br/>We discuss the consistent linearisation of the proposed model and its implementation in a monolithic fully coupled finite element framework. Special care has been taken on the implementation of the incompressibility constraint on the plastic deformation gradient. Finally, we present results for selected boundary value problems demonstrating the performance of the model.}},
  author       = {{Oppermann, Philip and Denzer, Ralf and Menzel, Andreas}},
  keywords     = {{Thermoplasticity; Finite element (FE) numerical modeling; Thermodynamics; Thermomechanics; Thermomechanical processes}},
  language     = {{eng}},
  month        = {{09}},
  title        = {{Thermo-Viscoplasticity for Case Hardening Steels at Finite Deformations and Wide Temperature Ranges}},
  url          = {{https://congress.cimne.com/complas2019/admin/files/fileabstract/a123.pdf}},
  year         = {{2019}},
}