Gradient-enhanced large strain thermoplasticity with automatic linearization and localization simulations

Pamin, Jerzy; Wcisło, Balbina; Kowalczyk-Gajewska, K.

doi:10.2140/jomms.2017.12.123

Cited by 7 publications

(7 citation statements)

References 46 publications

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“…The linear hardening/softening contribution (depending on the sign of H p ) to the yield stress is enhanced by the Laplacian of the micromorphic variable, a usual term in (31)…”

Section: Partial Differential Equation Governing the Micromorphic Var...mentioning

confidence: 99%

“…These problems are severely relevant to manufacturing process simulations because the material is heavily deformed in a short amount of time, thus inducing deformation localization and thermal softening. Moreover, it was already demonstrated that a strong size effect characterizes some manufacturing processes and that the classical continuum mechanics was no longer adequate to predict these behaviors [7,16,24,31,44].…”

Section: Introductionmentioning

confidence: 99%

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Regularization of shear banding and prediction of size effects in manufacturing operations: A micromorphic plasticity explicit scheme

et al. 2022

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Good quality manufacturing operation simulations are essential to obtain reliable numerical predictions of the processes. In many cases, it is possible to observe that the deformation localizes in narrow areas, and since the primary deformation mode is under shear, these areas are called shear bands. In classical continuum mechanics models, the deformation localization may lead to spurious mesh dependency if the material locally experiences thermal or plastic strain softening. One option to regularize such a non-physical behavior is to resort to non-local continuum mechanics theories. This paper adopts a scalar micromorphic approach, which includes a characteristic length scale in the constitutive framework to enforce the plastic strain gradient theory to regularize the solution. Since many manufacturing process simulations are often assessed through finite element methods with an explicit solver to facilitate convergence, we present an original model formulation and procedure for the implementation of the micromorphic continuum in an explicit finite element code. The approach is illustrated in the case of the VPS explicit solver from ESI GROUP. According to the original formulation, we propose an easy way to implement a scalar micromorphic approach by taking advantage of an analogy with the thermal balance equation. The numerical implementation is verified against the analytical solution of a semi-infinite glide problem. Finally, the correctness of the method is addressed by successfully predicting size effects both in a cutting and a bending tests.

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“…The linear hardening/softening contribution (depending on the sign of H p ) to the yield stress is enhanced by the Laplacian of the micromorphic variable, a usual term in (31)…”

Section: Partial Differential Equation Governing the Micromorphic Var...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Regularization of shear banding and prediction of size effects in manufacturing operations: A micromorphic plasticity explicit scheme

et al. 2022

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“…from which, the first ratios are equal to the rates of the viscoplastic multipliers: (40) and the second ones define the direction of the plastic flows, being equal to the one of the associated stress/couple stress:…”

Section: Viscoplastic Partmentioning

confidence: 99%

“…Upon material softening, a severe mesh dependence is experienced whether these equations were to be solved through Finite Element Modeling (FEM) [15,11,51]. On top of that, an accurate, thermodynamically-consistent material description must be employed to correctly capture the thermal softening induced by high plastic deformation [2,32,13,53,40]. Furthermore, the fact that during these processes the deformation is prone to localize in narrow areas makes it necessary to adopt numerical models which are able to predict size-effects [17,21,56,28,54,35,39,42,48].…”

Section: Introductionmentioning

confidence: 99%

Thermomechanics of Cosserat medium: modeling adiabatic shear bands in metals

Russo

Forest

Mata

2020

Continuum Mech. Thermodyn.

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During most metal manufacturing processes, the medium deforms by generating large quantities of plastic strain at relatively high strain rates, inevitably inducing rises in temperature. Metals characterized by low thermal conductivity properties might locally retain high temperatures, consequently undergoing thermal softening. The classical balance laws governing the continuum equilibrium show severe mesh sensitivity if they were numerically discretized through Finite Element Methods. Furthermore, the plastic deformation tends to localize in narrow areas whose characteristic length is comparable to grain size, thereby requiring the adoption of theories able to predict sizeeffects. In this manuscript we demonstrate that the Cosserat medium is able to overcome these issues related to manufacturing processes simulation. We first provide a thermodynamically-consistent description of the Cosserat medium, and then we propose a method to calibrate the two additional characteristic lengths introduced by the Cosserat medium description by enriching the model with the TANH stress flow rule under adiabatic conditions.

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“…Thermoplasticity and the related localisation effects are numerically investigated in, e.g. [27,28,42] and gradientenhancement by an additional differential equation introducing an internal length scale is proposed as a solution strategy to overcome mesh dependency issues.…”

Section: Introductionmentioning

confidence: 99%

A thermo-viscoplasticity model for metals over wide temperature ranges- application to case hardening steel

2021

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In this contribution, a model for the thermomechanically coupled behaviour of case hardening steel is introduced with application to 16MnCr5 (1.7131). The model is based on a decomposition of the free energy into a thermo-elastic and a plastic part. Associated viscoplasticity, in terms of a temperature-depenent Perzyna-type power law, in combination with an isotropic von Mises yield function takes respect for strain-rate dependency of the yield stress. The model covers additional temperature-related effects, like temperature-dependent elastic moduli, coefficient of thermal expansion, heat capacity, heat conductivity, yield stress and cold work hardening. The formulation fulfils the second law of thermodynamics in the form of the Clausius–Duhem inequality by exploiting the Coleman–Noll procedure. The introduced model parameters are fitted against experimental data. An implementation into a fully coupled finite element model is provided and representative numerical examples are presented showing aspects of the localisation and regularisation behaviour of the proposed model.

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Gradient-enhanced large strain thermoplasticity with automatic linearization and localization simulations

Cited by 7 publications

References 46 publications

Regularization of shear banding and prediction of size effects in manufacturing operations: A micromorphic plasticity explicit scheme

Regularization of shear banding and prediction of size effects in manufacturing operations: A micromorphic plasticity explicit scheme

Thermomechanics of Cosserat medium: modeling adiabatic shear bands in metals

A thermo-viscoplasticity model for metals over wide temperature ranges- application to case hardening steel

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