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B. Wcisło

Cracow University of Technology (PL)


Recent publications
1.  Mucha M., Wcisło B., Pamin J., Kowalczyk-Gajewska K., Instabilities in membrane tension: Parametric study for large strain thermoplasticity, ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING, ISSN: 1644-9665, DOI: 10.1016/j.acme.2018.01.008, Vol.18, No.4, pp.1055-1067, 2018

Abstract:
This paper deals with the numerical analysis of localized deformation for a rectangular plate in membrane tension, modelled with large strain thermoplasticity. The aim is to determine the influence of selected factors on the localization phenomena, which can result from geometrical, material, and thermal softening. Two types of boundary conditions are considered: plane stress and plane strain, as well as two yield functions, Huber–Mises–Hencky and Burzyński–Drucker–Prager, with selected values of friction angle. First, isothermal conditions are considered and next, a conductive case with thermal softening is studied. Moreover, three types of plastic behaviour are analysed: strain hardening (with different values of hardening modulus), ideal plasticity, and strain softening. Numerical tests, performed using AceGen/FEM packages, are carried out for the rectangular plate under tension with an imperfection, using three finite element discretizations. The results for plane strain in the isothermal model show that with the decrease of linear hardening modulus, we can observe stronger mesh sensitivity, while for plane stress, mesh sensitivity is visible for all cases. Furthermore, for the thermomechanical model the results also depend on the mesh density due to insufficient heat conduction regularization

Keywords:
Thermoplasticity, Large strains, Strain localization, Parametric study

Affiliations:
Mucha M. - Cracow University of Technology (PL)
Wcisło B. - Cracow University of Technology (PL)
Pamin J. - Cracow University of Technology (PL)
Kowalczyk-Gajewska K. - IPPT PAN
2.  Pamin J., Wcisło B., Kowalczyk-Gajewska K., Gradient-enhanced large strain thermoplasticity with automatic linearization and localization simulations, JOURNAL OF MECHANICS OF MATERIALS AND STRUCTURES, ISSN: 1559-3959, DOI: 10.2140/jomms.2017.12.123, Vol.12, No.1, pp.123-146, 2017

Abstract:
The paper deals with the thermomechanical extension of a large strain hyperelasto-plasticity model and focuses on algorithmic aspects and localization simulations. The formulation includes the degradation of the yield strength due to the increase of an averaged plastic strain measure and temperature, thus, three sources for loss of stability are included in the description. A gradient-enhancement of the model is incorporated through an additional differential equation, but localization is also influenced by heat conduction. The finite element analysis is performed for an elongated plate in plane strain conditions, using different finite elements and values of material parameters related to regularization (internal length scales are related to gradient averaging as well as heat conduction). In particular, the influence of the F-bar enrichment on the simulation results is studied. All computational tests are performed using selfprogrammed user subroutines prepared within a symbolic-numerical tool AceGen which is equipped with automatic differentiation options, allowing for automatic linearization of the governing equations.

Keywords:
thermoplasticity, softening, gradient averaging, strain localization, automatic linearization, AceGen package

Affiliations:
Pamin J. - Cracow University of Technology (PL)
Wcisło B. - Cracow University of Technology (PL)
Kowalczyk-Gajewska K. - IPPT PAN
3.  Wcisło B., Pamin J., Kowalczyk-Gajewska K., Gradient-enhanced damage model for large deformations of elastic-plastic materials, ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.65, No.5, pp.407-428, 2013

Abstract:
This paper deals with the development of a family of gradient-enhanced elasticity-damage-plasticity models for the simulation of failure in metallic and composite materials. The model incorporates finite deformations and is developed with the assumption of isotropy and isothermal conditions. The gradient enhancement applied to the damage part of the model aims at removing pathological sensitivity to the finite element discretization which can occur due to material softening.
The attention is focused on the algorithmic aspects and on the implementation of the model using AceGen tool. The numerical verification tests of the described model are performed using the Mathematica-based package AceFEM. Particularly, uniaxial tension test for a bar with a variable cross-section and tension of a perforated plate are examined.

Keywords:
arge strains, damage, plasticity, gradient-enhancement, AceGen package

Affiliations:
Wcisło B. - Cracow University of Technology (PL)
Pamin J. - Cracow University of Technology (PL)
Kowalczyk-Gajewska K. - IPPT PAN

Conference papers
1.  Wcisło B., Pamin J., Kowalczyk-Gajewska K., Menzel A., Numerical analysis of ellipticity condition for large strain plasticity, CMM 2017, 22nd International Conference on Computer Methods in Mechanics, 2017-09-13/09-16, Lublin (PL), DOI: 10.1063/1.5019150, Vol.1922, No.1, pp.140008-1-8, 2018

Abstract:
This paper deals with the numerical investigation of ellipticity of the boundary value problem for isothermal finite strain elasto-plasticity. Ellipticity can be lost when softening occurs. A discontinuity surface then appears in the considered material body and this is associated with the ill-posedness of the boundary value problem. In the paper the condition for ellipticity loss is derived using the deformation gradient and the first Piola-Kirchhoff stress tensor. Next, the obtained condition is implemented and numerically tested within symbolic-numerical tools AceGen and AceFEM using the benchmark of an elongated rectangular plate with imperfection in plane stress and plane strain conditions.

Affiliations:
Wcisło B. - Cracow University of Technology (PL)
Pamin J. - Cracow University of Technology (PL)
Kowalczyk-Gajewska K. - IPPT PAN
Menzel A. - Lund University (SE)
2.  Wcisło B., Żebro T., Kowalczyk-Gajewska K., Pamin J., Finite strain inelastic models with gradient averaging and AceGen implementation, ECCOMAX 2012, 6th European Congress on Computational Methods in Applied Sciences and Engineering, 2012-09-10/09-14, Wiedeń (AT), Vol.1, pp.1-15, 2012

Abstract:
This paper deals with the development of a family gradient-enhanced elasticity-damage-plasticity models for the simulation of failure in metallic and composite materials. The model incorporates finite deformations and is developed with the assumption of isotropy and isothermal conditions. The gradient enhancement applied to the damage part of the model aims at removing pathological sensitivity to the finite element discretization which can occur due to material softening. The attention is focused on the algorithmic aspects and on the implementation of the model using AceGen tool for automatic code generation, thus circumventing the cumbersome derivation of the consistent tangent for the Newton’s method. Numerical verification tests of the described model are performed with the Mathematica-based package AceFEM. Particularly, uniaxial tension test for a bar with a variable cross-section and tension of a perforated plate are examined.

Keywords:
large strain, damage, plasticity, gradient-enhancement, AceGen package

Affiliations:
Wcisło B. - Cracow University of Technology (PL)
Żebro T. - other affiliation
Kowalczyk-Gajewska K. - IPPT PAN
Pamin J. - Cracow University of Technology (PL)

Conference abstracts
1.  Wcisło B., Mucha M., Kowalczyk-Gajewska K., Pamin J., Large strain thermo-elasto-plasticity: simulation of shear banding for different stress states, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P169, pp.1-2, 2016

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